Quality report of the second wave of the European health interview survey : 2018 edition.
Date: 2018-05-29
Institutions: Eurostat
Subjects: data collection, health statistics, public health, report, sample survey

Quality report of the 
second wave of the 
European Health  
Interview survey

2018 edition

S T A T I S T I C A L 
R E P O R T S

STATISTICAL REPORTSQuality report of the second wave of the European Health Interview survey2018 editionQuality report of the 
second wave of the 
European Health 
Interview survey 

2018 edition 

Manuscript completed in April 2018 

Neither the European Commission nor any person acting on behalf of the Commission is responsible for 
the use that might be made of the following information. 

Luxembourg: Publications Office of the European Union, 2018 

© European Union, 2018 
Reuse is authorised provided the source is acknowledged.  
The reuse policy of European Commission documents is regulated by Decision 2011/833/EU (OJ L 330, 
14.12.2011, p. 39). 

Copyright for photographs: © Shutterstock/Moolek995  

For any use or reproduction of photos or other material that is not under the EU copyright, permission 
must be sought directly from the copyright holders. 
For more information, please consult: http://ec.europa.eu/eurostat/about/policies/copyright 

Authors: Anais Santourian & Stella Kitromilidou: Agilis SA Statistics & Informatics, w: www.agilis-sa.eu - 
p: P.O. BOX 78609, Tavros 177 01, GR - t: +30 211 100 3310 - e: contact@agilis-sa.eu 

The information and views set out in this publication are those of the authors and do not necessarily 
reflect the official opinion of the European Union. Neither the European Union institutions and bodies nor 
any person acting on their behalf may be held responsible for the use which may be made of the 
information contained therein. 

ISBN 978-92-79-82069-4 ISSN 2529-3222 doi: 10.2785/43982 KS-TF-18-003-EN-N 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table of contents 

Table of contents 

1. Introduction ........................................................................................................................ 7

2. The European Health Interview Survey (EHIS) ................................................................. 8

2.1.

Legal basis ............................................................................................................................................... 8

2.2. Methodological manual ........................................................................................................................... 8

2.3.

The EHIS wave 2 modules ...................................................................................................................... 9

3. Overview of the survey methodology in EHIS wave 2 ................................................... 10

3.1.

Target population .................................................................................................................................. 10

3.1.

Sampling design .................................................................................................................................... 12

3.1.1. Sampling frame ................................................................................................................................... 12

3.1.2. Sampling units ..................................................................................................................................... 13

3.1.3. Sampling design .................................................................................................................................. 15

3.1.4. Sample size ......................................................................................................................................... 16

3.1.5. Source data ......................................................................................................................................... 19

4. Overview of survey implementation in EHIS wave 2 ..................................................... 21

4.1.

Development of questionnaires ........................................................................................................... 21

4.1.1. Order of modules and submodules ..................................................................................................... 21

4.1.2. Languages in which the survey was carried out .................................................................................. 21

4.1.3. Pre-testing and pilot field testing ......................................................................................................... 22

4.2.

Data collection ....................................................................................................................................... 23

4.2.1. Mode of data collection ....................................................................................................................... 23

Topics administered via a self-completion questionnaire ........................................................................ 26

4.2.2. Interviewers ......................................................................................................................................... 26

4.2.3. Fieldwork (data collection) period ........................................................................................................ 28

5. Quality assessment.......................................................................................................... 31

5.1. Quality management ............................................................................................................................. 31

5.1.1. Method of pre-notification .................................................................................................................... 31

5.1.2. Incentives ............................................................................................................................................ 32

5.1.3. Duration of interviews .......................................................................................................................... 32

5.1.4. Methods used for quality control .......................................................................................................... 33

5.2.

Accuracy and reliability ........................................................................................................................ 35

5.2.1. Overall accuracy .................................................................................................................................. 35

5.2.2. Sampling errors ................................................................................................................................... 35

5.2.3. Non-sampling errors ............................................................................................................................ 41

Coverage errors ....................................................................................................................................... 41

Measurement errors ................................................................................................................................ 44

Non-response error ................................................................................................................................. 47

Processing error ...................................................................................................................................... 52

5.3.

Timeliness and punctuality ................................................................................................................... 52

5.4.

Comparability ......................................................................................................................................... 53

Quality report of the second wave of the European Health Interview survey 

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Table of contents 

5.4.1. Conceptual deviations ......................................................................................................................... 53

5.4.2. Problematic modules or questions ...................................................................................................... 55

5.4.3. Cross-country comparability................................................................................................................ 55
5.4.4. Comparability over time ....................................................................................................................... 56

5.5.

Coherence .............................................................................................................................................. 56

6. Conclusions ..................................................................................................................... 57

Annexes ................................................................................................................................ 60 

Annex 1 : Sampling design.................................................................................................. 60 

Annex 2 : Mode of data collection and use of administrative data ................................... 63 

Annex 3 : List of abbreviations and symbols ..................................................................... 66 

Quality report of the second wave of the European Health Interview survey 

4 

Executive summary 

Executive summary 

The European Health Interview Survey (EHIS) is a general population survey providing statistical information 
on health status, health determinants and healthcare activities in the European Union (EU). EHIS aims to 
providing statistical data, on a harmonized basis and with a high degree of comparability across EU Member
States (MS), supporting the monitoring of health policies on social inclusion and protection, health inequalities 
and healthy ageing.   

The collection of EHIS statistics at national level was launched for the first time (wave 1) between 2006 and 2009 
under a gentlemen’s agreement. It was implemented in 17 EU MSs, completed by Switzerland and Turkey. The 
second wave of EHIS (wave 2) was conducted between 2013 and 2015 in the 28 EU MS as well as in Iceland, 
Norway and Turkey under the Commission Regulation (EU) No 141/2013(1),(2), while the Commission
Implementing Decision of 19th February 2013(3) granted derogations to certain countries with regard to the
transmission of certain statistics. The survey will subsequently be run in 2019, followed at regular six-year 
interval (2025, 2031, etc.). 

The general coverage of the survey is the population aged 15 and over living in private households residing in 
the territory of the country at the time of data collection. In the national implementation of EHIS, countries could 
expand the survey population to younger age groups or persons living in collective households and in institutions. 
In those limited cases where countries expanded the survey population to younger age groups, respondents
from these age groups were excluded when calculating the respective effective sample size and when deriving
the EHIS statistical indicators. In all countries persons living in collective households and institutions were 
excluded from the target population.  

EHIS was nationally organized; it was conducted either as a stand-alone survey (in 20 countries), or as an 
element of another survey (in eight countries) or as a follow-up of another survey (in two countries). Across 
countries, the same set of variables was collected following the Commission implementing Regulation on EHIS. 
However, data were collected using national questionnaires, which sometimes comprised additional questions 
than those specified in the Commission Regulation, for national purposes. This was the case in 10 countries. 
Following Eurostat’s recommendations, most countries did not change the order of submodules or questions in 
their national questionnaires.  

Various types of sampling frames were used; notably results of a population census (five countries), population 
registers (15 countries), dwelling registers (three countries) or other statistical sources (seven countries). All 
countries made use of probability sampling with more than half of them making use of multi-stage sampling — 
with different sampling techniques applied within each sampling stage. 14 countries made use of single stage 
sampling. The number of interviews conducted within the household varied from one respondent to all household 
members. 

The data collection period (reference year) was spread over 2013 and 2015. In all countries, the data collection 
lasted at least three months, covering at least one month of the autumn season (September – November). On 
average, the data collection period across all countries lasted 8 months. Overall, the vast majority of responses 
were collected during the autumn season, followed by winter (December – February), spring (March – May) and 
summer (June – August) season.  

Different data collection modes were used. Data were obtained through postal questionnaires, face-to-face 
interviews, telephone interviews or web questionnaires, or a combination of these modes. In fact, 14 countries 
used a combination of those modes, while 12 countries used face-to-face interviews only, two countries used 
telephone interviews only and another two postal questionnaires only.  

With regard to the overall accuracy of the survey results, most countries stated that they followed Eurostat’s 
guidelines for the implementation of the survey. They also undertook required practices (e.g. validation, 
calibration, non-response adjustments, etc.) to minimize the effect of all potential sources of sampling and non-

(1) http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2013:047:0020:0048:EN:PDF 

(2) The Commission Regulation was amended in 2014 to take into account the accession of Croatia in the EU (Commission Regulation (EU) No 

68/24. 

(3 http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32013D0097 

Quality report of the second wave of the European Health Interview survey 

5 

Executive summary 

sampling errors. Standard errors, as key indicators commonly used as a measure of the reliability of data 
collected through sample survey, were provided by MSs for the three key indicators based on the Minimum 
European Health Module (MEHM), namely proportion of respondents in good or very good health (HS1), 
proportion of respondents with a longstanding illness (HS2) and proportion of respondents severely limited in 
activities people usually do because of health problems for at least the past 6 months (HS3), as well as 
proportion of respondents declaring having been hospitalized in the past 12 months (HO1) and proportion of 
respondents who are obese (BMI>=30).  

In order to reduce the risk for measurement and processing errors, pre-testing and pilot testing were used by 22 
countries for optimizing the data collection process and identifying potential sources of problems. Another 
potential source of introducing measurement error is the use of proxy interviews, i.e. when a person provides 
answers on another’s behalf. Proxy interviews were not allowed in all but 12 countries. From the 18 countries that 
permitted the use of proxy interviews, those were limited to the questions specified in the guidelines, with the 
exception of four countries, where proxy interviews were allowed for the whole set of questions. 

All countries made significant efforts to achieve high response rates (advance notification letters, at least three 
attempts for contacting selected persons before receiving a refusal for participation, three to five subsequent 
reminders). In few countries, non-respondents were substituted, while in a couple of countries, non-respondents 
were re-contacted through different modes than the ones initially used (e.g. through telephone or personal 
contact). The unit non-response rate ranged significantly across the MSs, from 16 % to about 70 %, with the 
respective rate not exceeding 40 % in 17 countries.  

Concerning item non-response, some variables, such that “need to receive help or more help with one or more 
self-care activities” (PC3), “time spent on doing sports, fitness or recreational physical activities in a typical week” 
(PE7), “time spent on bicycling to get to and from places on a typical day” (PE5), “need for help or more help with 
one or more domestic activities” (HA3) and “net monthly equivalised income of the household” (HHINCOME) 
recorded a non-response rate higher than 10 % in more than nine countries.  

Especially “net monthly equivalised income of the household” (HHINCOME) was frequently reported as a 
problematic variable, since respondents found it difficult to provide that information or considered the question 
sensitive. Similar issues were mentioned for variables concerning physical activity/exercise (PE), alcohol 
consumption (AL), mental health (MH), use of inpatient and day care (HO), chronic diseases (CD) and preventive 
services (PA). 

Overall, achieving an input standardisation is aimed at for EHIS by the instruments of the implementing 
regulation and the methodological guidelines. So, the common regulatory framework, variable definitions, 
conceptual guidelines and the proposed protocol for translation serve the basis to ensure comparability of the 
statistics among the participating countries. The vast majority of countries reported that the guidelines and the 
Commission implementing Regulation on EHIS have been closely followed. As consequence, it resulted in an 
overall sufficient or even good comparability across countries of the data and indicators from EHIS wave 2.

Quality report of the second wave of the European Health Interview survey 

6 

The European Health Interview Survey (EHIS) 

2

1 Introduction 

The present document constitutes the quality report of the second wave of the European Health Interview Survey 
(EHIS wave 2) conducted by the EU Member States (MS) between 2013 and 2015. This quality report makes a 
synthetic assessment of the quality of EHIS wave 2 data following the quality components and is further 
complemented by additional sections describing the characteristics of the national surveys as well as the 
statistical processes adopted at country level. The quality concept applied in this report is in conformity with the 
definition developed by the European Statistical System (ESS). It covers aspects of quality as presented in the 
quality report template developed by Eurostat including the following components: quality management, accuracy 
and reliability, timeliness and punctuality, coherence and comparability.  

EHIS wave 2 was carried out in all EU MS as well as in Iceland, Norway and Turkey. The individual quality reports 
that were delivered to Eurostat constitute the main source of information for the compilation of the present report. 
The document covers all 30 countries(4) that provided to Eurostat microdata from their EHIS wave 2 surveys
together with a national quality report.   

(4) Turkey delivered microdata to Eurostat, but a quality report was not made available. 

Quality report of the second wave of the European Health Interview survey 

7 

The European Health Interview Survey (EHIS) 

2

2 The European Health 

Interview Survey (EHIS) 

The European Health Interview Survey (EHIS) was developed between 2003 and 2006 with the goal of providing 
comparable cross-national data on health status, healthcare activities and health determinants. EHIS is a major 
EU reference source for evidence supporting health-related policies regarding healthy lifestyles, healthy ageing 
and well-being, health inequalities, healthcare access, quality of healthcare services, etc. 

The collection of EHIS statistics at national level had been launched for the first time (wave 1) between 2006 and 
2009 under a gentlemen’s agreement. It was fully or partly implemented in 17 EU MS(5), Switzerland and Turkey.
This first wave was driven by an input-harmonised approach with a model questionnaire, conceptual guidelines 
and a common translation protocol.  

Based on the outcomes of the data collection process undertaken under EHIS wave 1, Eurostat initiated a review 
process over the period 2010–2012 in order to improve and refine the survey instrument and facilitate the 
collection of comparable data on health topics related to the individual characteristics of the population. The 
results of the review process followed by detailed discussions held by the European Statistical System (ESS) 
bodies (ESS includes EFTA / EEA countries, but not EU Candidate Countries) led to the adoption of the 
adoption of the Commission Regulation on the implementation of EHIS wave 2 in the beginning of 2013. 

2.1. Legal basis 

The second wave of the EHIS (wave 2) was conducted between 2013 and 2015 in the 28 EU MS as well as in 
Iceland and Norway under the Commission Regulation (EU) No 141/2013(6),(7). Detailed specifications on the
data and metadata to be collected under EHIS are pursuant to the Commission Regulation (EU) No 141/2013, 
while the Commission Implementing Decision of 19th February 2013(8) grants derogations to certain countries
with regard to the transmission of certain statistics.  

2.2. Methodological manual 
The EHIS wave 2 methodological manual(9) drafted by Eurostat  provided / included / gave specific guidance to
countries for the planning and the implementation of EHIS wave 2. The methodological manual includes 
conceptual guidelines and interviewer instructions for all variables as well as statistical survey guidelines. It 
also gives instructions on 

(5) Belgium, Bulgaria, Czech Republic, Germany, Estonia, Greece, Spain, France, Cyprus, Latvia, Hungary, Malta, Austria, Poland, Romania, 

Slovenia and Slovakia. 

(6) http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2013:047:0020:0048:EN:PDF. The Commission Regulation was amended in 2014 

to take into account the accession of Croatia in the EU (Commission Regulation (EU) No 68/2014). 

(7) The Commission Regulation applies to the EU-28 MSs as well as Iceland and Norway. Turkey is concerned by the Regulation implementing 

EHIS via the monitoring of the compliance of the enlargement countries with the EU acquis in the field of statistics. Turkey delivered microdata 
to Eurostat although a national quality report was not made available. 

(8) http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32013D0097 

(9) http://ec.europa.eu/eurostat/documents/3859598/5926729/KS-RA-13-018-EN.PDF/26c7ea80-01d8-420e-bdc6-e9d5f6578e7c 

Quality report of the second wave of the European Health Interview survey 

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The European Health Interview Survey (EHIS) 

2

the data processing and transmission.  

A model questionnaire was given in the Annex of the methodological manual. In general, the order of modules,
sub-modules and questions is given in the model questionnaire.  

2.3. The EHIS wave 2 modules 

The survey is composed of three broad public health areas, named modules; the European Health Status 
Module (EHSM), the European Health Determinants Module (EHDM) and the European Health Care Module 
(EHCM), as well as of a set of core demographic and socio-economic variables.   

Each module consists of health-related sub-modules. In total EHIS wave 2 consists of 21 health-related sub-
modules, as follows: 

 European Health Status Module (EHSM). The module on health status is a central point of the survey. It

allows the measurement of the health status of the population in general and not only in relation with 
specific health problems. It covers different aspects and dimensions of health such as health status 
(HS), having specific diseases and chronic conditions (CD), occurrence of accidents and injuries (AC), 
absence from work (due to health problems) (AW), physical and sensory functional limitations (PL), 
difficulties with personal care activities (PC), difficulties with household activities (HA), having pain (PN) 
and specific aspects of mental health (MH). 

 European Health Care Module (EHCM): The ECHM collects data on the use of health care services and the
unmet needs for health care. It permits the collection of information on health care consumption that is 
comparable across countries and enables the linking of the data with characteristics of health status, 
health determinants and socioeconomic characteristics. It includes aspects such as use of inpatient and 
day care services (HO), use of ambulatory and home care (AM), medicine use (MD), use of preventive 
services (PA), and unmet needs for health care (UN). 

 European Health Determinants module (EHDM): The focus of this module is to the measurement of aspects
in the lifestyles or health-related behaviors of Europeans. It covers aspects such as weight and height 
(BM), performing physical activity / exercise (PE), consumption of fruits and vegetables (FV), smoking 
behavior (SK), alcohol consumption (AL), social support (SS) and provision of informal care or 
assistance (IC). 

Quality report of the second wave of the European Health Interview survey 

9 

Overview of survey methodology in EHIS wave 2 

3

3 Overview of the  

survey methodology 
in EHIS wave 2 

3.1. Target population 

According to the Commission Regulation implementing EHIS, the target (reference) population shall include 
individuals aged 15 and over living in private households residing in the territory of the MSs at the time of the 
data collection. In the national implementation of EHIS, countries could expand the survey population to younger 
age groups or persons living in collective households and in institutions. In those cases, these additional 
respondents should be excluded when calculating the respective effective sample sizes.   

Persons living in collective households or institutions were generally excluded from the target population. A few 
examples of definitions for collective households and institutions used in some countries are provided below: 

In Austria, institutions covered homes for the elderly, nursing homes, psychiatric institutions, institutions for 
mentally handicapped, boarding schools, monasteries, prisons and homes for refugees, in Croatia, institutions 
included dormitories, rest homes, eventide homes, day care centres, orphan's homes, prisons, barracks, hotel-
motel guest houses, houses of army members and stay in pay hospitals, whereas in Lithuania and Estonia 
institutions covered care institutions for the elderly and disabled people, child care and imprisonment institutions. 
Latvia considered as institutions correctional and penal institutions, student's hostels, social welfare institutions, 
municipal (night) shelters for the homeless, boarding schools and specialized boarding schools, addiction and 
psychiatric institutions and religious institutions.  

In Romania, institutionalized persons were those who lived in elderly homes, centres for disabled persons, 
penitentiaries, closed facilities for young persons and care homes. On the other hand, Slovakia, assumed that 
institutions covered all dwellings other than private households. By definition, in Germany, homeless people and 
people travelling during the time of data collection are not included in the survey. In Ireland, institutions include 
educational establishments, nursing/children's homes, hospitals, prison, shelters/refuges (including 
accommodation for homeless persons), other types of establishment, while in Italy, those include public or private 
facilities that provide residential social and/or health care services.  

Refugees, hospitals, homes for the elderly, schools, hotels and hostels, institutions for disabled people, prison 
and rehabilitation centres are defined as institutions in Malta. Similarly, in Belgium, institutionalized people 
covered prisoners, patients of psychiatric institutions and large monasteries. Finally, the United Kingdom covers 
exclusively the population living in private households, with a couple of notable exceptions, i.e. Communal 
Establishments (CE). Furthermore, in the United Kingdom household members aged 16 and over were eligible to 
participate in EHIS. 

Following the Commission Regulation implementing EHIS, small parts of the national territories of certain 
countries were excluded from the survey. In detail, in the Netherlands, persons living in Caribbean Islands and 
the West Frisian Islands (with the exception of Texel) were excluded from the survey.  France did not include 
persons living in Overseas Departments and territories. In the United Kingdom households of Scotland north of
the Caledonian Canal and the Scilly Islands were excluded from the sampling frame. In Ireland, all offshore 
islands with the exception of Achill, Bull, Cruit, Gorumna, Inishnee, Lettermore, Lettermullan and Valentia were 
excluded.  

Quality report of the second wave of the European Health Interview survey 

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Overview of survey methodology in EHIS wave 2 

3

Table 1 presents the figures for the target and non-target population across countries.  

Table 1. Target and non-target population in EHIS wave 2 

Non-target population 

Target population 

Number of individuals younger 
than 15 

Number of individuals living 
in institutions 

BE (1)

BG 
CZ (2)

DK 

DE 

EE 

IE 

EL 

ES 
FR (2)

HR 

IT 
CY (3)

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 
RO (2)

SI 

SK 

FI 
SE (4)
UK (5)

IS 

9 214 798 

6 204 002 

8 933 025 

4 697 098 

69 821 396 

1 107 791 

3 608 662 

9 150 412 

38 959 700 

51 009 842 

3 604 266 

52 068 782 

703 511 

1 670 644 

2 500 517 

423 716 

8 267 203 

345 606 

13 979 215 

7 235 423 

32 370 934 

8 884 581 

16 835 792 

1 758 564 

4 591 168 

4 487 327 

7 901 091 

49 937 000 

249 773 

: 

998 196 

1 591 000 

959 592 

10 686 723 

209 596 

920 693 

: 

6 500 000 

11 810 093 

652 428 

8 383 122 

: 

295 348 

430 100 

88 637 

1 417 000 

61 728 

2 850 074 

1 200 000 

5 746 084 

1 490 241 

3 069 095 

302 520 

830 000 

: 

1 682 033 

12 100 000 

66 742 

: 

: 

168 000 

: 

886 044 

13 000 

62 383 

: 

250 000 

1 384 312 

38 576 

367 485 

: 

26 175 

23 700 

: 

141 000 

8 649 

249 942 

122 000 

3 61 584 

125 000 

71 318 

: 

180 000 

: 

: 

1 119 000 

: 

NO 
(1) Persons living in institutions, although not eligible, are included in the sampling frame. Selected non-eligible persons are then substituted. 

4 233 409 

933 955 

38 500 

(2) Figures on the population living in institutions refer those aged 15 years and over.  

(3) The number of persons in the non-target population cannot be calculated since the sampling frame consists of households. 

(4) Figures under the field “number of individuals younger than 15 years” refer to the total non-target population.  

(5) Persons aged less than 16 years. 

: Information not available. 

Quality report of the second wave of the European Health Interview survey 

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Overview of survey methodology in EHIS wave 2 

3

3.1. Sampling design 

3.1.1. Sampling frame 

Three main types of sampling frames were used; notably results from the most recent population census, 
population registers and dwelling registers (see Table 2). Therefore, countries can be classified into the following 
groups based on the sampling frame used:  

 Population register: In 15 countries, namely, Belgium, Denmark, Germany, Estonia, Spain, Italy, Lithuania,
Hungary, Malta, the Netherlands, Slovenia, Finland, Sweden, Iceland and Norway a population register 
is used as a data source for building the sampling frame.  

 Dwelling register: Poland, Portugal and Slovakia used data coming from a dwelling register as a sampling

frame. 

 Population census: Countries using the most recent population census data as a sampling frame were:

Bulgaria, Ireland, Greece, Croatia and Cyprus. 

 Other: In the Czech Republic, France, Latvia, Luxembourg, Austria, Romania and the United Kingdom, the

following sources are used: 

o Czech Republic: the sampling frame is the sample of the 5th wave respondents of LFS. The

LFS sample is drawn from Census Enumeration Units and the Building Register.

o

o

o

o

France: the sample frame is made of registers of beneficiaries from the national health
insurance schemes.

Latvia: the Demographic Statistics Data Processing System, which contains data from the
Population Register and the National Real Estate Cadastre, was the main source for the
compilation of the sampling frame. Population census statistics were used for making
adjustments to the sampling frame (exclusion of persons that, most likely, are not national
residents).

Luxembourg: the sample was drawn from the National Health Insurance Database (IGSS)
which covers 95 % of the population.

Austria: the LFS sample is used for the recruitment of respondents for EHIS. The sample frame
of the LFS is the Central Register of Residence.

o Romania: for all household surveys a master sample is used, namely the Multifunctional

Sample of Territorial Areas (EMZOT), which is derived as a sample of geographical areas.
EMZOT was built based on the Population and Housing Census in March 2002, was
operational in early 2004 and was updated in 2006 and 2015.

o United Kingdom: EHIS wave 2 for Great Britain was a follow-up of the LFS. The sample was

drawn from LFS respondents who consented to participate also to other surveys. For Northern
Ireland, the Land and Property Services Agency gazetteer listing private households was used
for deriving the sample.

Quality report of the second wave of the European Health Interview survey 

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Overview of survey methodology in EHIS wave 2 

3 

Table 2. Data source for building the sampling frame for EHIS wave 2 

Population register 

Dwelling register 

Population census 

Other 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK 

IS 

NO 

YES 

NO 

NO 

YES 

YES 

YES 

NO 

NO 

YES 

NO 

NO 

YES 

NO 

NO 

YES 

NO 

YES 

YES 

YES 

YES 

NO 

NO 

NO 

YES 

NO 

YES 

YES 

NO 

YES 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

YES 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

3.1.2. Sampling units 

In accordance with the methodological guidelines, the statistical unit in EHIS is the individual. In practice, the 
sampling unit was the dwelling, the household or the individual, depending on the design chosen by the country 
and the sampling frame used for selecting the sample.  

As shown in Table 3, in 21 out of 30 countries the ultimate sampling unit(10) is the individual. Additional five 
countries selected a sample of households while another four countries selected a sample of dwellings.  

(10) The last stage of sampling (regardless of its number) is called an ultimate sampling unit (USU). 

Quality report of the second wave of the European Health Interview survey 

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Overview of survey methodology in EHIS wave 2 

3 

The sampling unit used by countries relies heavily on the frame used for selecting the sample. For instance, in all 
countries that used a population register as a sampling frame (see Table 2), except for Belgium and Italy, a 
sampling of persons of age 15 and over was selected at the final stage of sampling (regardless of its number). 
Instead, in countries where the population census results were used as a data source for the sampling frame, 
dwellings or households were selected (Bulgaria, the Czech Republic, Greece, Cyprus and Croatia). Similarly, 
Poland, Portugal, Romania and Slovakia selected a sample of dwellings since the sampling frame was the 
dwelling register. 

Table 3. Sampling units in EHIS wave 2 

Dwelling 

Household  

Individual 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK 

IS 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

NO 

YES 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

NO 

YES 

YES 

Quality report of the second wave of the European Health Interview survey 

14 

 
 
 
 
 
 
Overview of survey methodology in EHIS wave 2 

3 

3.1.3. Sampling design 

The national sampling designs in the EHIS wave 2 implementation varied (see Table 4).  

The most common design was a two or three stage stratified or systematic (cluster) sampling, selecting more 
frequently in the first stage census enumeration areas, or otherwise municipalities, blocks of households or 
administrative districts: 

  Two-stage sampling (Bulgaria, Germany, Croatia, Italy, Latvia (CAPI data collection mode), Hungary, the 

Netherlands, Poland, Romania and Slovenia),  

  Three-stage sampling (Belgium, the Czech Republic, Ireland, Greece, Spain, Portugal and Slovakia). 

Denmark, Estonia, France, Cyprus, Latvia (CATI data collection mode), Lithuania, Luxembourg, Malta, Austria, 
Finland, Sweden, the United Kingdom (for Northern Ireland), as well as Iceland and Norway used a single stage 
sampling, i.e. either a simple random, or stratified, systematic or cluster sampling design.  

In Latvia, a combination of two sampling designs was used; the population frame was split in two primary strata 
(CAPI and CATI) depending on the availability of information of a phone number. Then a two-stage sampling 
design was used for CAPI data collection mode and one-stage sampling design was used for CATI data 
collection mode.   

Especially, in the Czech Republic and Austria, where EHIS was conducted as a follow-up of the LFS, the sample 
was drawn from the pool of respondents that were successfully interviewed during the 5th LFS wave (normally the 
last visit) and that were also willing to participate in EHIS. Similarly, in the United Kingdom (for Scotland and 
Wales), a random sample, stratified by country, was drawn from the final-wave households participating in LFS. 
Only those aged 16 or over who were willing to participate in future surveys were selected for EHIS.  

Table 4. Sampling design in EHIS wave 2 
Sampling unit 

Sampling design 

Dwelling 

Systematic multistage cluster sampling 

Country 

PT 

Stratified multistage (cluster) sampling 

PL, ES, HR, RO, SK 

Household 

Systematic multistage cluster sampling 

BG 

Stratified multistage (cluster) sampling 

BE, EL, IE 

Multistage  sampling  with  probability  proportional 
to size 
Systematic sampling 

Stratified sampling 

Simple random sampling 

IT 

UK (2) 

CY 

UK (2) 

Individual 

Systematic stratified multistage sampling 

LV (CAPI) 

Multistage random sampling 

HU 

Multistage stratified sampling 

Simple random sampling 

Cluster sampling 

Systematic stratified sampling 

CZ (1), DE, NL, SI 

DK, LT, FI, IS 

FR 

EE 

Stratified sampling 

LV (CATI), LU, MT, AT, SE, NO 

(1) The description refers to the selection of a sample for LFS (PSUs and SSUs) and a follow-up selection of individuals from households 

participating in 5th wave of LFS for EHIS (TSU). Individuals for EHIS were selected using Simple Random Sampling. 

(2) In Scotland and Wales a sample, stratified by country, was drawn from the final-wave LFS households. As a follow-up survey, only those aged 
16 or over who had not objected to take part in future surveys were selected for EHIS. The LFS sample is selected using systematic sampling 
from the postcode address file (PAF) ordered by postcode. For Northern Ireland, a simple random sample of households from the Land and 
Property Services Agency gazetteer was selected. 

Quality report of the second wave of the European Health Interview survey 

15 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Overview of survey methodology in EHIS wave 2 

3 

As a general note, it can be mentioned that most countries that applied a single stage sampling have used a 
frame different from a population register for drawing their samples. Instead, Denmark, Estonia, Lithuania, Malta, 
Finland, Sweden as well as Iceland and Norway have drawn their sample using a single stage design, although a 
population register has been used as a sampling frame.   

Annex 2 (Table 25) of the present document provides a more detailed presentation of the sampling designs, the 
sampling units in each sampling stage as well as the probability used to draw the sample across countries.  

3.1.4. Sample size 

Table 5 presents the reached sample size, the reached effective sample size, the minimum effective sample size 
as specified in the Commission Regulation implementing EHIS, as well as the ratio of the reached effective 
sample size to the minimum effective sample size.  

In methodological manual for EHIS, for the minimum effective sample size, the reference is to the effective 
sample size of persons, which is the size required if the survey was based on simple random sampling (design 
effect in relation to the “percentage of people severely limited in daily activities” variable=1.0)(11). The actual 
sample sizes should be larger to the extent that the design effects exceed 1.0 and to compensate for all kinds of 
non-response. 

For the reached sample size, the actual response cases have been taken into consideration. The reached 
effective sample size was derived by dividing the reached sample size to the design effect provided in the 
national quality reports for the variable on “general activity limitation” (HS3).  

The reached effective sample size in comparison to the minimum effective sample size is depicted in Figure 1. 
The ratio of the reached effective sample size to minimum effective sample size ranged from 0.66 (Belgium) to 
2.17 (Latvia).  

Especially in Malta and Sweden, the required sample size was determined by increasing the minimum sample 
size specified in the Commission Regulation implementing EHIS by an anticipated non-response rate, whereas 
Portugal assumed anticipated non-response rate of 25 % and a design effect of 1.5.  

Figure 1. Minimum effective sample size and reached effective sample size in EHIS wave 2 

Note: Data not available for the reached effective sample size for Denmark, Estonia, Croatia, Malta, Portugal, Romania, Finland, Sweden, 
Iceland and Norway. 

(11) Following the specifications in the methodological manual, the variable on “general activity limitation” (HSE3), i.e. the “percentage of people 

severely limited in daily activities” has been taken as the most critical variable for determining the required sample size in terms of the precision 
requirements.  

Quality report of the second wave of the European Health Interview survey 

16 

05 00010 00015 00020 00025 000BEBGCZDKDEEEIEELESFRHRITCYLVLTLUHUMTNLATPLPTROSISKFISEUKISNOMinimum effective sample size specified in the regulationReached effective sample size 
 
 
 
 
                                                           
Overview of survey methodology in EHIS wave 2 

3 

Table 5. Sample size in the national EHIS wave 2 

Reached 
sample 
size 

Design effect 
for HS3 
variable 

Reached 
effective 
sample size 

Minimum 
effective 
sample size 

BE 

BG 

CZ 

DK (1) 

DE 

EE (1) 

IE 

EL 

ES (1) 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT (1) 

NL 

AT 

PL 

PT (1) 

RO (1) 

SI 

SK 

FI 

SE (1) 

UK 

IS (1) 

NO (1) 

9 113 

6 410 

6 737 

5 811 

24 824 

5 452 

10 323 

8 223 

22 842 

15 729 

5 446 

25 325 

4 958 

7 077 

5 205 

4 004 

5 826 

4 086 

7 653 

15 771 

24 156 

18 204 

16 605 

6 262 

5 490 

6 183 

6 292 

20 161 

4 001 

8 164 

2.1 

1.3 

1.0 

: 

1.6 

: 

1.5 

1.5 

1.5 

1.3 

0.0 

1.2 

1.0 

0.7 

0.8 

1.0 

0.8 

: 

1.1 

1.5 

1.2 

: 

: 

1.3 

1.0 

1.0 

: 

1.4 

: 

: 

4 297 

5 008 

6 478 

: 

6 500 

5 920 

6 510 

5 350 

15 146 

15 260 

: 

6 928 

5 367 

14 929 

11 826 

: 

21 776 

4 948 

9 870 

6 426 

3 931 

6 905 

: 

7 289 

10 729 

20 824 

: 

: 

4 673 

5 719 

6 183 

: 

14 130 

: 

: 

4 270 

5 057 

6 667 

11 620 

13 110 

5 000 

13 180 

4 095 

4 555 

4 850 

4 000 

6 410 

3 975 

7 515 

6 050 

10 690 

6 515 

8 420 

4 486 

5 370 

5 330 

6 200 

13 085 

3 940 

5 170 

(1) Information not available for the design effect of HS3 variable.  

: Information not available. 

Ratio of the reached 
effective sample size to 
minimum effective 
sample size 
0.66 

0.85 

1.00 

: 

0.99 

: 

1.37 

0.81 

1.28 

0.90 

: 

1.65 

1.21 

2.17 

1.32 

0.98 

1.08 

: 

0.97 

1.77 

1.95 

: 

: 

1.04 

1.06 

1.16 

: 

1.08 

: 

: 

Quality report of the second wave of the European Health Interview survey 

17 

 
 
 
 
 
 
Overview of survey methodology in EHIS wave 2 

3 

Table 6 presents summary statistics on the distribution of weights in the microdata files transmitted by MSs to 
Eurostat. As expected, the range of weights is higher for countries that the target population is relatively larger 
(Germany, Spain, France and the United Kingdom). High variability is observed in the distribution of weights for 
Belgium, although the target population is, relatively, not large, while the opposite holds for Austria, Poland and 
Portugal.  

Table 6. Summary statistics on the distribution of weights in EHIS wave 2 

BE 
BG 
CZ 
DK 

DE 
EE 
IE 
EL 
ES 
FR 
HR 

Minimum 

1st Quartile 

15 
357 
442 
516 

179 
18 
120 
51 
59 
308 
136 

306 
755 
791 
582 

1 671 
167 
213 
560 
845 
2 197 
456 

Median 
684 
889 
934 
740 

2 616 
199 
275 
853 
1 397 
2 860 
576 

IT 
CY 
LV 
LT 
LU 
HU 
MT 
NL 
AT 
PL 
PT 
RO 
SI 
SK 
FI 
SE 
UK 
IS 
NO 
Source: Calculations based on national EHIS microdata files.  

1 617 
97 
180 
392 
85 
1 155 
61 
1 503 
253 
728 
113 
559 
210 
644 
536 
1 065 
1 063 
53 
319 

108 
2 
53 
278 
75 
560 
33 
859 
53 
256 
13 
256 
76 
300 
463 
613 
118 
41 
107 

2 094 
133 
220 
448 
95 
1 370 
86 
1 729 
355 
1 143 
244 
791 
264 
819 
641 
1 236 
1 888 
58 
474 

Mean 
927 
968 
1 326 
808 

2 813 
201 
351 
1 113 
1 706 
3 243 
662 

2 056 
142 
236 
480 
101 
1 419 
87 
1 793 
459 
1 337 
488 
1 014 
281 
837 
723 
1 282 
2 548 
62 
525 

3rd Quartile 
1 230 
1 110 
1 768 
987 

Maximum 
14 150 
2 466 
7 100 
1 505 

3 616 
237 
366 
1 372 
2 253 
3 948 
776 

2 503 
177 
269 
594 
112 
1 632 
101 
2 016 
524 
1 741 
679 
1 350 
335 
994 
842 
1 460 
3 254 
65 
644 

11 770 
546 
2 284 
4 000 
17 560 
14 370 
2 172 

4 835 
392 
1 164 
735 
186 
2 800 
186 
3 667 
7 391 
6 521 
5 393 
4 526 
1 257 
2 173 
1 399 
3 234 
15 000 
116 
2 092 

Quality report of the second wave of the European Health Interview survey 

18 

 
 
 
 
 
 
 
Overview of survey methodology in EHIS wave 2 

3 

A boxplot on the distribution of weights is presented in Figure 2 providing an overview of their range and 
variability. 

Figure 2. Boxplot of the distribution of weights in EHIS wave 2 

Source: Calculations based on national EHIS microdata files.  

3.1.5. Source data 

As shown in Table 7, EHIS was implemented as a stand-alone survey, i.e. it did not form part of or was not 
combined with another survey / questionnaire in 20 countries as well as the United Kingdom as far as Northern 
Ireland is concerned. Especially, in Finland, although EHIS was carried out as an independent survey, the same 
procedures and service providers as for the regional health and well-being survey were used.  

Quality report of the second wave of the European Health Interview survey 

19 

02 0004 0006 0008 00010 00012 00014 00016 00018 000BEBGCZDKDEEEIEELESFRHRITCYLVLTLUHUMTNLATPLPTROSISKFISEUKISNO 
 
 
 
 
 
 
 
Table 7. Source data in EHIS wave 2 

Survey name 

Overview of survey methodology in EHIS wave 2 

3 

EHIS is a 
stand-
alone 
survey 

EHIS is 
combined 
with another 
survey 

EHIS is a 
follow-up of 
another 
survey 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 
UK (1) 

IS 

NO 

Health Interview Survey 

European Health Interview Survey 

European Health Interview Survey 2014 

European Health Interview Survey 

German Health Update 

Estonian Health Interview Survey 

Irish Health Survey 

Health Survey 

European Health Interview Survey in Spain 

Health, Healthcare and Insurance Survey (ESPS) 

European Health Interview Survey - wave 2 

European Health Interview Survey 

European Health Interview Survey 2014 

European Health Interview Survey 

Health Interview Survey 

National Health Survey 

European Health Interview Survey 

European Health Interview Survey 

Health Interview Survey 

Austrian Health Interview Survey 2014 

European Health Interview Survey 

National Health Survey 2014 

European Health Interview Survey 

Health Interview Survey 2014 

European Health Interview Survey 2014 

European Health Interview Survey 

European Health Interview Survey 

European Health Interview Survey 

Health Interview Survey 

Survey  of  Living  Conditions  - Health,  Care,  Social 
Relations 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

YES 

YES 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

YES 

NO 

YES 

NO 

YES 

YES 

YES 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

(1) In Great Britain, EHIS was conducted as a follow-up to LFS, while in the Northern Ireland the survey was stand-alone.   

On the other hand, EHIS has been embedded in an existing survey conducted for national purposes in eight 
countries: Belgium (Health Interview Survey), the Czech Republic (Health Examination Survey), Germany 
(Health Interview Survey), Estonia (Health Interview Survey), Ireland (Quarterly National Household Survey), 
France (Health Interview Survey) and the Netherlands (Health Interview Survey) as well as Norway (Living 
Conditions Survey). Particularly in Croatia, the EHIS questionnaire was followed by a separate questionnaire 
“Tobacco questions for surveys” for the Centre for Disease Control and Prevention (CDC) and the World Health 
Organisation (WHO).  

In the Czech Republic, EHIS was carried out as a follow-up of the Labour Force Survey (LFS), as was the case 
in Austria and in the United Kingdom (as far as Great Britain is concerned).  

Quality report of the second wave of the European Health Interview survey 

20 

 
 
 
 
 
 
Overview of survey implementation in EHIS wave 2 

4 

4  Overview of survey 

implementation  
in EHIS wave 2 

4.1. Development of questionnaires 

4.1.1. Order of modules and submodules 

The recommended order of modules and submodules was followed by all countries, except for Belgium, Greece, 
Estonia, France, Italy, the Netherlands and Norway. More specifically, Belgium integrated EHIS questions in the 
HIS questionnaire in accordance with the guidelines regarding the order for the modules. Greece moved the 
questions on income at the end of the questionnaire due to their sensitivity. Estonia changed the order of certain 
questions (AC2, HA2, HA3, PA1, PE7, AL3 and AL5) in order to be in line with the 2006 national questionnaire. 
Finally, France separated PL2 to PL5 questions in order to be in line with the National Health, Health Care and 
Insurance Survey (ESPS).  

Italy moved the sub-module on absence from work due to health problems (AW) at the end of the questionnaire, 
while in the Norwegian questionnaire, the same sub-module was moved from the Health Status Module (EHSM) 
to the Health Care Module (EHCM). Also, questions on provision of informal care or assistance were moved from 
the Health Determinants Module (EHDM) to the Health Care Module (EHCM). In Austria, the sub-module on 
physical activity (PE) was part of the self-administered questionnaire, sent to respondents by post after the 
completion of the telephone interview. 

The Czech Republic, Greece, Croatia, Italy, Cyprus, Latvia, Lithuania, Luxembourg, Austria and Sweden 
mentioned that additional questions were included for national purposes. Additionally, Poland incorporated in the 
questionnaire additional questions for adults and a separate questionnaire for children aged 0–14.  

Additional information on the modifications introduced in the national questionnaires is provided under Section 
5.4.1. 

4.1.2. Languages in which the survey was carried out 

In 14 countries (Belgium, Estonia, Ireland, Spain, Italy, Cyprus, Latvia, Lithuania, Luxembourg, Malta, Finland, 
Sweden as well as Iceland and Switzerland) the survey was undertaken into more than one official languages 
(Table 8). In total, 27 languages were used, ten of which were common in more than one country.  

Quality report of the second wave of the European Health Interview survey 

21 

 
 
 
 
 
 
 
 
Table 8. Language in which the survey was carried out in EHIS wave 2 

Language 

Language 

BE 

Dutch / French / German 

LU  German / French / Portuguese / English 

Overview of survey implementation in EHIS wave 2 

4 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

Bulgarian 

Czech 

Danish 

German 

Estonian / Russian  

English / Irish (upon request) 

Greek (in some areas such as Rodopi and Xanthi 
survey was carried out using translators) 

HU  Hungarian 

MT  Maltese / English 

NL  Dutch 

AT  German 

PL 

PT 

Polish 

Portuguese 

RO  Romanian 

Spanish  /  Regional  official  languages  (Catalan, 
Valenciano, Euskera, Gallego) / English 

SI 

Slovene 

French 

Croatian 

Italian, Slovene, German (South Tyrolean) 

Greek / English 

Latvian / Russian 

Lithuanian / Russian / Polish 

SK 

FI 

SE 

Slovak 

Finnish / Swedish 

Swedish / English 

UK  English 

IS 

Icelandic / English 

NO  Norwegian / English 

Almost all countries used the translation protocol proposed by Eurostat except for Belgium, Spain, France, 
Lithuania, the Netherlands, Iceland and Norway. In Belgium, the translation of the questionnaire was made by a 
team consisting of experts (Dutch / French), whereas the administration of the German community translated the 
French version into German. Cyprus followed the protocol for the Greek version of the questionnaire, while in 
Spain a private company translated the questionnaire in the regional official languages. Experts translated the 
Lithuanian questionnaire into Russian and Polish, and similarly in Ireland, experts within the NSI in cooperation 
with health specialists translated the English version of the questionnaire into Irish. In the Netherlands, the 
Flemish version of the questionnaire used under wave 1 was adapted to reflect the specificities of the Dutch 
language, whereas in Norway, the questionnaire was translated by an expert who was in close cooperation with 
the health division. Moreover, where possible, questions on health were harmonized with the corresponding 
questions in the EU-SILC questionnaire. 

4.1.3. Pre-testing and pilot field testing 

The questionnaire was simply tested or reviewed by experts in the Czech Republic, Germany, Estonia, Ireland, 
France, Croatia, Lithuania (Lithuanian version only), Hungary, Malta, Austria, Slovenia and Sweden, Iceland and 
Norway.  

Cognitive testing was carried out by Cyprus (Greek version), the Netherlands (for selected variables), Poland 
(Polish version only) and Slovakia (except for core variables).  

Especially Iceland, Italy (Italian version only) and Latvia tested the questionnaire not only through simple but also 
by cognitive testing. In France, a self-administered questionnaire was tested on a sample of 100 persons for the 
health module, while in the United Kingdom, the questionnaire was tested by the staff of the NSI.  

The questionnaire was not pre-tested at all in Belgium, Bulgaria, Denmark, Greece, Spain, Luxembourg, 
Portugal, Romania and Finland.  

However, in Belgium a convenience sample was drawn for pilot field testing (e.g. wording ambiguities, filters), 
whereas Luxembourg invited 1 000 persons to participate in the field testing for verifying the quality of the 
questionnaire, technical issues (e.g. computer programs) as well as familiarising the survey staff with potential 
practical problems. 

Quality report of the second wave of the European Health Interview survey 

22 

 
 
 
 
 
 
 
Overview of survey implementation in EHIS wave 2 

4 

A pilot field testing was conducted in Germany during October 2013 and June 2014 in order to optimize its 
incentive and contact strategies, while in the United Kingdom, a small-scale telephone survey to 200 households 
in combination with 52 face-to-face interviews was undertaken with the view to test the routing of the 
questionnaire and to identify potential issues with the comprehension of the questions. Similarly, a pilot field 
testing exercise to 31 participants was conducted in Norway with the view to identify potential issues with the 
wording of the questions, to test the routing of the questionnaire and to record the time required for the 
completion of the questionnaire.   

4.2. Data collection 

4.2.1. Mode of data collection 

In the national EHIS implementation, countries could use various modes of data collection (including 
combinations of them), namely face-to-face interviews, telephone interviews, postal or web interviews. Whether 
postal and web modes for data collection were applied, self-administered questionnaires were used.  

Table 9 shows the data collection mode used in the national EHIS implementation. The table also presents in its 
last column whether any EHIS variables (including technical and core social ones) were completed from 
administrative data sources. 

A more detailed presentation of the data collection modes used is presented in Annex 2 (Table 25). 

Of the 30 countries, 12 countries used face-to-face interviews as the only mode of data collection (Belgium, 
Bulgaria, Greece, Spain, Italy, Cyprus, Lithuania, Hungary, Malta, Poland, Romania and Slovakia) but seven of 
them (Belgium, Bulgaria, Italy, Lithuania, Malta, Romania and Slovakia) used a self-administered mode for some 
parts of the questionnaire.  

Austria, Iceland and Norway used telephone interviews as a mode for data collection. Notwithstanding, in 
Sweden, a sample of those who did not respond to the self-administered survey was called and interviewed by 
phone, while in Austria a paper questionnaire was sent by post to the respondents of the telephone survey for the 
completion of the sub-module on physical activity (PE). 

In the Czech Republic, France, Croatia, Latvia and the United Kingdom, a combination of personal visits and 
telephone interviews was applied. From the latter five countries, all but Croatia and the United Kingdom used 
also self-administered questionnaires. Especially in France, core social variables and questions on unmet needs 
were collected through face-to-face or telephone interviews, while a paper questionnaire was sent by post to the 
respondents for the completion of the health questions. 

Another group of countries, namely, Estonia, Portugal and Slovenia, used a combination of face-to-face 
interviews and self-administered web questionnaires as modes of data collection. In the Netherlands, an attempt 
for a face-to-face interview was made if the no response was received after two reminders. 

Finally, Denmark, Germany, Ireland, Luxembourg and Finland used exclusively self-administered questionnaires 
as a mode for data collection, as opposed to Greece, Spain, Croatia, Cyprus, Hungary, Poland, the United 
Kingdom, Iceland and Norway that did not use a self-administered questionnaire at all.    

With regard to the use of administrative data, 14 countries, namely, Belgium, Denmark, Germany, Estonia, 
France, Latvia, Lithuania, the Netherlands, Slovenia, Finland, Sweden, the United Kingdom, Iceland and Norway 
derived information from administrative sources for the compilation of certain EHIS variables concerning the 
socio-demographic characteristics of the respondents (see Annex 2 (Table 25)). As a general remark, it can be 
stated that in countries where a population or the social security register was used as a sampling frame, 
administrative data were used for the derivation of certain EHIS variables.   

Quality report of the second wave of the European Health Interview survey 

23 

 
 
 
 
 
Table 9. Mode of data collection used in EHIS wave 2 
Telephone 
interviews 

Face-to-face 
interviews 

Overview of survey implementation in EHIS wave 2 

4 

Self-administered 
questionnaire 

Use of 
administrative 
data 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 
FR (1) 

HR 

IT 

CY 
LV (2) 

LT 

LU 

HU 

MT 
NL (3) 

AT 

PL 
PT (3) 

RO 

SI 

SK 

FI 
SE (4) 

UK 

IS 

NO 

YES 

YES 

YES 

NO 

NO 

YES 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

YES 

YES 

YES 

NO 

YES 

YES 

YES 

YES 

YES 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

NO 

YES 

NO 

YES 

NO 

YES 

YES 

YES 

NO 

YES 

YES 

YES 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

NO 

NO 

NO 

YES 

NO 

YES 

YES 

YES 

YES 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

NO 

YES 

YES 

NO 

NO 

NO 

YES 

NO 

YES 

YES 

YES 

YES 

YES 

(1) Core social variables and variables on unmet needs are filled in during face-to-face or telephone interviews using electronic version 

(CAPI/CATI). Health variables are filled via paper self-administered questionnaire. Corsica was surveyed only by telephone.  

(2) The use of a web self-administered questionnaire was not allowed those aged between 15 and 17. Self-administered questionnaires were not 

used in face-to-face interviews. 

(3) A letter was sent asking persons to complete the self-administered electronic questionnaire. If after two reminders no response was received, 

an attempt for a personal interview was made. 

(4) An invitation to participate to the online survey was sent to a group of the sampled persons. A strategic sample of those who did not respond to 

the self-administered survey was further approached for a telephone interview. 

Quality report of the second wave of the European Health Interview survey 

24 

 
 
 
 
 
 
 
 
 
Overview of survey implementation in EHIS wave 2 

4 

In recent years, web surveys are increasingly used due to the advantages they offer (reduced cost, speed of data 
collection, easiness of implementation). Respondents can answer the questionnaire at their own pace, whereas 
studies have shown that respondents tend to provide more reliable answers to sensitive questions when a self-
administered  mode  is  used.  However,  the  risk  for  measurement  errors  is  higher  (e.g.  questions  may  be 
misunderstood). Another consideration is that part of the target population may not have access to Internet and 
therefore, bias might be introduced.  

Finland for example used postal non-electronic questionnaires. As stated in the quality report, this mode of data 
collection resulted in a relatively higher item non-response rate and no severe errors were detected during the 
data processing stage, although incoherent answers were identified in many cases.  

On the other hand, the use of a face-to-face or telephone interviews provides the opportunity to respondents to 
ask for clarifications in questions, while real time validation may be also implemented when an electronic version 
is used. Again, one may consider interviewer bias, or measurement errors due to the presence of an interviewer.  

The use of administrative data sources reduces the overall response burden provided that required data follow 
the same definitions, concepts, reference period, etc.   

Given all the above, and taking into consideration the peculiarities of  the EHIS survey (e.g. sensitive questions, 
necessity for further explanations), most countries used a multimode data collection.  

Figure 3 presents the distribution of responses by mode of data collection based on the information derived from 
EHIS microdata.  

Figure 3. Distribution of responses by mode of data collection in EHIS wave 2 
(%) 

(1) Main mode of data collection is postal since only the core social variables and variables on unmet needs were collected via face-to-face or 
telephone interviews.  

(2) Very limited number of responses were received through the web questionnaire.  

(3) Face-to-face interviews in combination with paper self-completion questionnaires during the interview were used. 

Source: Calculations based on national EHIS microdata files.  

With regard to the mode of administration of the survey, three countries used solely Computer Assisted Personal 
Interviews (CAPI), seven used solely Paper-and-Pencil Interviews (PAPI), two used solely Computer Assisted 
Telephone Interviews (CATI), another six used a combination of CAPI / CATI / PAPI, while another 10 countries 
used a combination of CAPI / PAPI / CATI / CAWI and finally another two used a combination of PAPI / CAPI and 
Telephone, non-electronic version. 

Overall, the mode administration of the survey, following the mode of data collection is summarized below.  

A more detailed presentation is provided in Annex 2 (Table 25).  

  Face-to-face interviews: From the 21 countries that used face-to-face interviews at least as one of their 

methods for data collection, 11 of them used CAPI, seven used PAPI and the remaining three of them 

Quality report of the second wave of the European Health Interview survey 

25 

0102030405060708090100France (¹)FinlandIreland (²)SwedenDenmarkGermanyLuxembourgCzech RepublicBulgariaGreeceSpainCyprusLithuaniaHungaryMaltaPolandSlovakiaItalyPortugalEstoniaCroatiaSloveniaLatviaNetherlandsUnited KingdomBelgium (³)AustriaRomania (³)IcelandNorway(%)PostalFace-to-faceTelephoneUse of internetMixed mode 
 
 
 
 
 
Overview of survey implementation in EHIS wave 2 

4 

used a mixed method of PAPI - CAPI.  

  Telephone interviews: Seven (France (only for core social variables and variables on unmet needs), Latvia, 
Austria, Sweden, the United Kingdom, Iceland and Norway) out of nine countries that used telephone 
interviews as one of their modes for the collection of data used CATI.  

  Self-administered questionnaire: The majority of countries used a self-administered mode either for some 

parts of the questionnaire or for the whole questionnaire:  

  Paper questionnaire: Eight countries used paper questionnaires either sending them by post 
(Denmark, Germany, Ireland, France, Luxembourg, Austria (only for variables on physical 
exercise), Finland and Sweden) or giving directly to respondent the paper questionnaire to 
reply specific questions (Belgium, Bulgaria, the Czech Republic, Italy, Lithuania, Malta, the 
Netherlands, Romania, Slovakia).  

  Use of internet: Six countries (Estonia, Ireland, Latvia, the Netherlands, Portugal and Slovenia) 

used Computer-assisted web interviewing (CAWI) for self-administered questionnaires.  

  Paper questionnaire and use of internet: Denmark, Germany and Luxembourg and Sweden 
used a mixed method of data collection of the self-administered questionnaires. More 
specifically, Luxembourg and Sweden sent an invitation letter and the respondents had two 
options: (a) answering an electronic questionnaire based on the instructions sent in the 
invitation letter or (b) completing a paper questionnaire.  

TOPICS ADMINISTERED VIA A SELF-COMPLETION QUESTIONNAIRE 

13 countries allowed respondents to fill-in themselves sub-modules or variables when a mode other than a self-
administered one was used. In Denmark, Germany, Luxembourg and Finland, all questions could be 
administered by the respondents via a self-completion questionnaire.  

A group of countries, namely, Bulgaria, Italy, Lithuania, Malta, Romania and Slovakia allowed for a self-
administered mode for variables concerning smoking (SK) and alcohol consumption (AL), while the same holds 
for the Netherlands as far as alcohol consumption sub-module was concerned. In France and Ireland, a self-
administered mode was allowed for all variables except for unmet needs for health care (UN) and accidents and 
injuries (AC), respectively.  

Belgium allowed for self-reports on health status (HS), alcohol consumption (AL), mental health (MH), physical 
exercise (PE), smoking (SK) and social support (SS) sub-modules. In Austria, a paper questionnaire was sent by 
post to the respondents of the telephone survey for the completion of the sub-module on physical activity (PE). 
On the contrary, France permitted self-completion to all questions except for those under the module on the 
unmet needs for health care (UN).   

4.2.2. Interviewers 

In 13 countries, namely, Bulgaria, the Czech Republic, Estonia, Ireland, Latvia, Lithuania, Hungary, the 
Netherlands, Poland, Slovakia, the United Kingdom as well as Iceland and Norway, the interviews have been 
undertaken by the staff of the NSI that was experienced in health or social surveys (Table 10).  

In Belgium, France, Croatia, Italy, Malta, Austria and Portugal, external staff experienced in health / social 
surveys was recruited, whereas in Romania and Sweden, the interviewers have participated in other household 
surveys. In Greece and Cyprus interviewers and supervisors are recruited on a seasonal basis and were 
selected based on their qualifications and previous experience, while in Slovenia, external staff was employed 
about three quarters of which had some previous experience in social surveys. The rest of the interviewers were 
beginners and thus, had undergone an extensive training.  

In Denmark, Germany, Luxembourg and Finland, no interviews have been undertaken, since a self-administered 
mode was used for the data collection.  

Quality report of the second wave of the European Health Interview survey 

26 

 
 
 
Overview of survey implementation in EHIS wave 2 

4 

Table 10. Interviewers qualifications and ratio of interviews per interviewer in EHIS wave 2 

Ratio interviews / 
interviewers 

Internal staff 
experienced in 
health / social 
surveys 

External staff 
experienced in health / 
social surveys 

External staff 
experienced in 
household or other 
surveys 

BE 

BG 

CZ 
DK (3) 
DE (3) 

EE 
IE (4) 
EL (1) 

ES (2) 

FR 

HR 

IT 

CY 

LV 

LT 
LU (3) 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 
FI (3) 

SE 

UK 

IS 

50:1 

53:1 

36:1 

- 

- 

77:1 

208:1 

8 - 55:1 

15:1 

14:1  
(Face-to-face) 
63:1 
(Telephone) 

67:1 

24:1 

248:1 

157:1 

61:1 

- 

22:1 

102:1 

27:1 

15:1 

22:1 

100:1 

32:1 

27:1 

40:1 

- 

: 

33:1 

111:1 

NO 

YES 

YES 

NO 

NO 

YES 

YES 

NO 

YES 

NO 

NO 

NO 

NO 

YES 

YES 

NO 

YES 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

YES 

NO 

NO 

YES 

YES 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

YES 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

NO 

NO 

NO 

YES 

NO 

NO 

NO 
(1) The number of questionnaires assigned to each interviewer depends on the sample in its region and on the maximum number of interviews 

YES 

NO 

NO 

57:1 

that each interviewer may undertake as defined by the NSI. 

(2) The ratio of interviews to interviewers is provided on a weekly basis.  

(3) A self-administered mode has been used for the data collection. No interviews have been undertaken.  

(4) The ratio of interviews to interviewers has been calculated as average per quarter.  

: Information not available; -: Not applicable. 

Quality report of the second wave of the European Health Interview survey 

27 

 
 
  
 
 
Overview of survey implementation in EHIS wave 2 

4 

All countries organized a special training session of the interviewers, who received instructions about the scope 
of the survey, the content of the questionnaire, the modules included in the questionnaire, practicing in filling-in 
the questionnaire and responding to questions. In most countries, interviewers were also provided with manuals 
and training material.  

The average interviewer workload, i.e. the ratio of interviews per interviewer, varied significantly across countries, 
with the lowest ratio being recorded for Austria (15 to 1) and the largest one to Cyprus (248 to 1).  

4.2.3. Fieldwork (data collection) period 

According to article 4.3 of the Commission Regulation implementing EHIS, the data collection period should be 
spread over at least three months, including at least one month of the autumn season. 

Figure 4 shows the duration of the EHIS fieldwork / data collection period. In Cyprus, Estonia, Lithuania, 
Luxembourg, Hungary, the Netherlands, Poland, Portugal, Romania, Slovenia and Slovakia, the data collection 
has taken place in 2014 covering at least three or four months including the autumn season.  

In Bulgaria, the Czech Republic, Germany, Greece, Spain, France, Croatia, Latvia, Malta, Finland and Sweden 
the fieldwork started during 2014 and was completed in 2015, while in Austria the data collection was launched in 
October 2013 and was completed in June 2015. On the other hand, in Belgium, the data collection has taken 
place in 2013.  

Denmark, Italy and Norway carried out the fieldwork during the last months of 2015. Just in Ireland the fieldwork 
started in 2014 and lasted until the first four months of 2016.  

Additionally, in most countries, the data collection period lasted more than three months. It ranged from three 
(Denmark, Italy, Lithuania, Hungary, Romania) peaking at 19 months (Ireland) and 21 months (Austria).  

On average, the data collection period across all countries lasted 8 months. 

Figure 4. Fieldwork (data collection) period in EHIS wave 2 

(1) The fieldwork was carried out during April 2013 – March 2014 as far as Great Britain is concerned and during April 2014 – September 2014 as 

far as Northern Ireland is concerned. 

Quality report of the second wave of the European Health Interview survey 

28 

JanFebMarAprMayJunJulAugSepOctNovDecJanFebMarAprMayJunJulAugSepOctNovDecJanFebMarAprMayJunJulAugSepOctNovDecJanFebMarAprBEBGCZDKDEEEIEELESFRHRITCYLVLTLUHUMTNLATPLPTROSISKFISEUK (1)ISNO2013201420152016 
 
 
 
 
 
Based on calculations made on the microdata files transmitted to Eurostat, the distribution of responses over the 
reference years is presented in Table 11.  

Overview of survey implementation in EHIS wave 2 

4 

Table 11. Distribution of responses over the reference years in EHIS wave 2  
(number of respondents, %) 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK 

IS 

2013 

9 113 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

3 566 

0 

0 

0 

0 

0 

0 

0 

14 062 

0 

Number 

2014 

0 

6 347 

6 498 

0 

9 375 

5 452 

2 015 

8 223 

21 163 

15 397 

4 110 

0 

4 958 

4 426 

5 205 

4 004 

5 826 

1 340 

7 653 

7 796 

24 156 

18 204 

16 605 

6 262 

5 490 

5 268 

6 248 

6 099 

0 

NO 
Source: Calculations based on national EHIS microdata files.  

0 

0 

2015 

0 

63 

239 

5 811 

15 449 

0 

8 308 

0 

1 679 

332 

1 336 

25 325 

0 

2 651 

0 

0 

0 

2 746 

0 

4 409 

0 

0 

0 

0 

0 

915 

44 

0 

4 001 

8 164 

2013 

100.0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

22.6 

0 

0 

0 

0 

0 

0 

0 

69.7 

0 

0 

% 

2014 

0 

99.0 

96.5 

0 

37.8 

100.0 

19.5 

100.0 

92.6 

97.9 

75.5 

0 

100.0 

62.5 

100.0 

100.0 

100.0 

32.8 

100.0 

49.4 

100.0 

100.0 

100.0 

100.0 

100.0 

85.2 

99.3 

30.3 

0 

0 

2015 

0 

1.0 

3.5 

100.0 

62.2 

0 

80.5 

0 

7.4 

2.1 

24.5 

100.0 

0 

37.5 

0 

0 

0 

67.2 

0 

28.0 

0 

0 

0 

0 

0 

14.8 

0.7 

0 

100.0 

100.0 

As expected, in Estonia, Cyprus, Lithuania, Luxembourg, Hungary, the Netherlands, Poland, Portugal, Romania, 
Slovenia, Slovakia, as well as the United Kingdom, all interviews have been undertaken during 2014. Just in 
Greece, the (official) data collection fieldwork lasted until April 2015, although all data were collected during 
2014. In Belgium, responses were collected in 2013, whereas in Denmark, Italy and Norway in 2015. In the 
United Kingdom, the data collection was undertaken during 2013–2014 with the main bulk of responses being 
collected in 2013, while in Austria, the data collection was spread over the three-year period 2013–2015, with the 
highest proportion of responses being collected in 2014. In the rest of the countries, the data were collected 
during 2014 and 2015.  

Quality report of the second wave of the European Health Interview survey 

29 

 
 
 
 
 
 
 
 
 
 
Figure 5 shows the overall distribution of response over the reference months of the survey (independently of the 
year that the survey was undertaken in each country). The majority of responses were collected during 
September (15.4 %), October (22.5 %) and November (22.9 %). Overall, as also shown in Figure 5, less 
responses were collected during the spring and summer periods. 

Overview of survey implementation in EHIS wave 2 

4 

Figure 5. Distribution of response over the reference months  
(number of respondents) 

Source: Calculations based on national EHIS microdata files.  

Quality report of the second wave of the European Health Interview survey 

30 

010 00020 00030 00040 00050 00060 00070 00080 000JuneJulyMarchAprilAugustMayFebruaryJanuaryDecemberSeptemberOctoberNovember 
 
 
 
Quality assessment 

5 

5  Quality assessment 

5.1. Quality management 

5.1.1. Method of pre-notification 

As shown in Table 12, all countries used a letter to pre-notify the selected persons about the launch of the survey 
and their inclusion in the sample, except for Ireland that made a doorstep contact for the announcement of the 
survey.  

Except for the dispatch of the pre-notification letter Austria, Belgium, the Czech Republic and Latvia also 
contacted the selected persons via telephone. The latter three countries together with Ireland, Croatia, the 
Netherlands, Poland and Slovenia also attempted to make a contact at the door. Especially Estonia, sent pre-
notifications emails, in addition to the paper letters.  

Table 12. Method used for pre-notification of respondents for the launch of the survey in EHIS wave 2  

Belgium, Bulgaria, Czech Republic, Denmark, Germany, Estonia, Greece, Spain, 
Croatia, France, Italy, Cyprus, Lithuania, Latvia, Luxembourg, Hungary, Malta, 
Netherlands, Austria, Poland, Portugal, Romania, Slovenia, Slovakia, Finland, Sweden, 
United Kingdom, Iceland, Norway. 

Belgium, Czech Republic, Latvia, Austria. 

Letter 

Telephone 

Belgium, Czech Republic, Ireland, Croatia, Latvia, Netherlands, Poland, Slovenia. 

Personal contact 
at doorstep 

Estonia. 

Email 

All countries, except for Germany and Luxembourg, made at least three attempts for contacting the selected 
persons before receiving a refusal for participation. Moreover, the Netherlands used personal contacts at 
doorstep only for those who have not replied after the dispatch of two notification letters.  

Quality report of the second wave of the European Health Interview survey 

31 

 
 
 
 
 
 
 
 
 
 
Quality assessment 

5

5.1.2. Incentives 

Seven countries offered incentives to the respondents to encourage them to participate in the survey. In Malta 
and Austria shopping vouchers and gift vouchers were offered, respectively. In Belgium, each participating 
household has been paid 10 Euros, while in the Czech Republic a reflective tape and a shopping cart chip with 
EHIS logo was offered. In Slovakia and Estonia each respondent received a pen and reflectors and key-holders, 
respectively. Finally, Germany launched two incentive strategies: a shopping voucher of 10 Euros was given to 
respondents aged 15 to 34, while respondents aged more than 34 could win the lottery shopping voucher of 50 
euros. 

5.1.3. Duration of interviews 

Table 13 presents the duration of interviews by mode of data collection. It should be however highlighted that is 
not always clear from the information provided in the national quality reports whether the figures provided refer to 
the interview duration for EHIS variables only or for the whole questionnaire that might include additional 
questions for national purposes.  

The average duration of completion of the face-to-face interviews varied from 20 (Spain) to 45 minutes (Greece 
and Cyprus) and peaking at 47 minutes in Malta, while the average duration for the telephone interviews varied 
from 20 (Austria) to 65 minutes (Estonia for CAPI interviews). 

Concerning the self-administered questionnaires, the average duration ranged from 10 (Estonia) to 46 minutes 
(Latvia). In Finland, it is estimated — since only self-administered questionnaires were used — that it took about 
40 to 60 minutes for the respondents to complete the whole questionnaire. 

However, Bulgaria, the Czech Republic, Lithuania, Romania, Slovenia and Sweden did not mention explicitly in 
their national quality reports the average duration of the interviews by mode of data collection. 

It is also notable that in Bulgaria, France, Croatia, Italy, Cyprus, Poland and Romania all persons aged 15 and 
over in the same household have been surveyed. This signifies that the completion time is multiplied in each 
household. On the other hand, in Greece and the Czech Republic only one person has been surveyed in the 
household. 

Additionally, the use of administrative data by some countries (see Annex 2, (Table 25)) for the derivation of 
some variables has probably resulted in the reduction of the overall average time of completion of the 
questionnaire.  

In some countries, various data collection modes are in place. From the available information, it can be deducted 
that electronic modes of data collection tend to reduce the time of completion of the questionnaire. Portugal is an 
exception (41 minutes required for CAWI and 34 minutes for paper questionnaire).  

Quality report of the second wave of the European Health Interview survey 

32 

Table 13. Average duration of interviews (in minutes) in EHIS wave by mode of data collection (minutes) 

Quality assessment 

5 

Face-to-face 

Telephone 

Self-administered 
questionnaire 

BE 
BG (2) 
CZ (3) 

DK 
DE (4) 
EE 

IE 
EL (3) 

ES 

FR 

HR 

IT 

CY 

LV 

LT 
LU (5) 

HU 

MT 

NL 

AT 

PL 

PT 
RO (2) 

SI 

SK 
FI (4) 

SE 

UK 

IS 

NO 

: 

30 

: 

- 

- 
65 

: 

45 

5-20 

27 

25 

58 

30-45 

27 

35 

- 

: 

47 

31 

- 

30 

34 

: 

: 

: 

- 

- 

46 

- 

- 

- 

- 

: 

- 

- 
: 

- 

- 

- 

21 

22 

- 

- 

24 

- 

- 

- 

- 

- 

20 

- 

- 

- 

- 

- 

- 

: 

38 

25 

34 

: 

: 

: 

: 

35 
10 

: 

- 

- 

20 

- 

- 

- 

46 

- 

27 

- 

- 

31 

: 

- 

41 

: 

: 

: 

20-60 

: 

- 

- 

- 

Undefined mode of data 
collection (1) 
: 

43 

- 

- 
: 

: 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

31 

30 

: 

- 

25 

- 

- 

- 

(1) No explicit reference in the quality reports on the interview duration by mode of data collection.  

(2) All persons aged more than 15 years in the same household have been surveyed. 

(3) Only one person per household has been surveyed. 

(4) Based on NSI's estimation. 

(5) Information refers to the web survey using an electronic questionnaire. Information about the duration of interviews where a paper 

questionnaire was used is not available.  

: Information not available; -: Not applicable mode of data collection. 

5.1.4. Methods used for quality control 

In order to safeguard that the interviews have been indeed undertaken by the interviewers and to receive 
feedback on the quality of the interview (e.g. interviewer’s behavior, duration of interview), most countries 
contacted, usually via telephone, a sample of randomly selected respondents (see Table 14). The ratio of 
interviewers to field supervisors varied from 2 to 1 (Italy), 4 to 1 (Bulgaria, Croatia, Cyprus) to 70 to 1 (Belgium). 

Quality report of the second wave of the European Health Interview survey 

33 

 
 
 
  
 
Table 14. Method for quality control of the data collection and ratio of interviewers to field supervisors in 
EHIS wave 2 

Ratio 
interviewers / 
field 
supervisors 

Contacts with 
respondents 
for quality 
control 

Contact method 

Quality assessment 

5 

Contact (via letter) requesting for an assessment of the 
interview. 

Telephone contacts by the regional coordinators to selected 
respondents. 

Letters sent to respondents requesting for feedback on the 
survey. 

Telephone contacts (18 %) and personal visits (10 %) to 
selected persons. 

112 respondents whose interview duration lasted less than 10 
min. were called back. 

Telephone contacts with 10 % randomly selected respondents. 

Telephone contacts to randomly selected households. 
Telephone contacts, personal visits or mails dispatched to 5 % of 
addresses. 
Telephone contacts to 26 % randomly selected respondents. 

Telephone contacts to 10% randomly selected respondents 
Checks conducted by the NSI’s staff concerning the duration of 
the interview for a sample of randomly selected questionnaires 
(15 % of filled-in questionnaires) per interviewer. 
Telephone contacts (7.4 %) undertaken under the framework of 
the Dutch HIS. 

Telephone contacts to 3 % randomly selected respondents. 

Direct contacts with households. 
Telephone contacts of at least 10 % randomly selected 
respondents per interviewer. Mails were also sent raising a 
number of questions on the conducting of the interview, length of 
the questionnaire, use of show cards, etc. 

BE 

BG 

CZ 

DK (1) 
DE (1) 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 
LU (1) 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 
SE (2) 

UK 

IS 

70:1 

4:1 

13:1 

NO 

NO 

12:1 

9:1 
1 supervisor per 
regional office 

5-6:1 

15:1 
(Face-to-Face) 
7:1 
(Telephone) 
4:1 

2:1 

4:1 

11:1 

7:1 

NO 

13:1 

10:1 

13:1 

15:1 

5:1 

9:1 

8:1 

YES 

NO 

YES 

NO 

NO 

YES 

NO 

NO 

YES 

YES 

YES 

NO 

YES 

YES 

YES 

NO 

YES 

YES 

YES 

NO 

NO 

YES 

YES 

50:1 

YES 

17:1 

NO 

: 

10:1 
(Face-to-face) 
20:1 
(Telephone) 
18:1 

NO 

NO 

NO 

NO 

NO 

NO 
(1) The survey was primarily conducted via a self-administered mode. 

14:1 

NO 

(2) The survey was primarily conducted via a self-administered mode. Telephone interviews were conducted to those who did not reply the self-

administered questionnaire. 

Quality report of the second wave of the European Health Interview survey 

34 

 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Quality assessment 

5 

5.2. Accuracy and reliability 

5.2.1. Overall accuracy 

With regard to the overall accuracy of the survey results, most countries stated that they followed Eurostat’s 
guidelines for the implementation of the survey and undertook required practices (e.g. validation, calibration, non-
response adjustments, etc.) to minimize the effect of all potential sources of non-sampling errors. 

The Czech Republic and Finland referred to specific factors that might have affected the accuracy of the results. 
In detail, the Czech Republic reported that since the sample was derived from the LFS, interviewers may have 
been used to cooperate with a certain person within household, which was not selected to participate also in 
EHIS. Additionally, in the national version of the questionnaire, additional chronical diseases have been added in 
the list proposed by Eurostat under the chronic conditions (CD) section, which might have affected the results. 
Care should be also given to the fact that some concepts did not have the same meaning at national level (e.g. 
hospitalization which is a term not commonly used in the national health care system). The latter may have 
impact on the responses for one-day cases of hospitalization.  

In Finland, the use of a self-administered questionnaire resulted in higher item nonresponse rate, whereas invalid 
and incoherent values were also identified. Although no severe errors were detected during the data processing 
phase, the accuracy of the results might have been affected.  

Moreover, France and Luxembourg stated that some sociodemographic groups of the population were 
underrepresented (see Section on Coverage errors).  

5.2.2. Sampling errors 

Sampling errors are in place only in sample surveys and arise from the fact that not all units of the population 
frame are surveyed. Surveys, like EHIS, are based on probability sampling. This makes it possible to quantify the 
sampling errors, which can be expressed in terms of standard errors and confidence intervals.  

Quality report of the second wave of the European Health Interview survey 

35 

 
 
 
 
Table 15 provides the estimates, the standard errors, the 95 % confidence limits and the design effect for the 
proportion of respondents aged 15 years or over who were in good or very good health (HS1).  

Table 15. Sampling errors — Respondents aged 15 years or over in good or very good health (HS1) 

Number of 
respondents — n 

Estimated 
proportion — p 

Standard error 
— SE 

95 % confidence 
interval 

Design effect 
— deff 

Quality assessment 

5 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 
HR (1) 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 
UK (2) 

IS 

NO 

5 024 

3 568 

3 892 

4 211 

24 707 

3 116 

7 979 

5 419 

15 388 

10 778 

2 839 

17 416 

3 640 

6 780 

2 259 

2 736 

3 547 

3 152 

5 903 

12 669 

22 363 

8 091 

11 109 

4 070 

3 330 

6 130 

4 788 

12 776 

2 886 

6 534 

77.9 

66.6 

68.4 

75.3 

70.9 

59.1 

81.4 

74.8 

71.0 

69.4 

60.4 

70.4 

76.4 

49.0 

50.3 

69.6 

61.4 

81.6 

77.3 

78.6 

62.8 

51.3 

72.7 

65.8 

65.7 

59.4 

25.1 

75.8 

74.3 

79.3 

(1) Coefficient of variation instead of design effect.  

(2) Figures refer to the population aged 16 and over.  

: Information not available. 

0.70 

0.80 

0.66 

0.57 

0.38 

0.70 

0.72 

0.60 

0.65 

0.41 

0.74 

0.34 

0.60 

0.50 

0.57 

0.72 

0.53 

0.61 

0.48 

0.40 

0.37 

0.51 

0.61 

0.64 

0.64 

0.60 

0.55 

0.42 

0.70 

0.52 

76.5 - 79.3 

65.1 - 68.2 

67.1 - 69.7 

 74.2 - 76.4 

70.1 - 71.6 

57.7 - 60.4 

79.9 - 82.9 

73.6 - 75.9 

69.7 - 72.3 

68.6 - 70.2 

58.9 -  61.8 

69.7 - 71.1 

75.2 - 77.6 

48.0 - 50.0 

49.4 - 51.3 

68.2 - 71.0 

60.4 - 62.4 

80.4 - 82.8 

78.2 - 76.4 

77.8 - 79.4 

62.0 - 63.5 

50.3 - 52.3 

71.5 - 73.9 

64.5 - 67.1 

64.5 - 67.0 

58.1 - 60.6 

23.8 - 26.0 

 74.9 - 76.6 

72.9 - 75.7 

78.3 - 80.3 

1.92 

1.69 

1.16 

: 

1.75 

: 

1.63 

1.47 

4.73 

1.26 

0.01 

1.41 

1.07 

0.74 

0.82 

0.96 

0.68 

: 

1.05 

1.22 

1.33 

: 

: 

1.13 

1.01 

1.00 

: 

1.70 

: 

: 

Quality report of the second wave of the European Health Interview survey 

36 

 
 
 
 
 
 
 
Table 16 provides the estimates, the standard errors, the 95 % confidence limits and the design effect for the 
proportion of respondents aged 15 years or over with a longstanding illness or health problem (HS2).  

Table 16. Sampling errors — Respondents aged 15 years or over with a longstanding illness or health 
problem (HS2) 

Quality assessment 

5 

Number of 
respondents — n 
1 953 

Estimated 
proportion — p 
28.3 

Standard error 
— SE 
0.80 

95 % confidence 
interval 
26.8 - 29.9 

Design effect 
— deff 
2.10 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR (1) 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK (2) 

IS 

3 110 

4 649 

 2 055 

24 645 

 3 582 

3 791 

4 589 

14 734 

5 747 

2 183 

 8 127 

2 350 

7 072 

3 052 

1 322 

2 644 

1 530 

2 641 

5 626 

24 156 

11 134 

5 838 

2 483 

3 199 

6 059 

2 084 

 10 679 

 1 204 

44.6 

60.5 

 33.3 

44.9 

64.9 

30.7 

49.3 

62.0 

37.7 

36.7 

0.80 

0.75 

 0.62 

0.42 

0.70 

0.54 

0.80 

0.59 

0.44 

0.71 

 31.6 

 0.45 

42.5 

45.9 

52.8 

33.3 

45.1 

33.8 

33.9 

36.0 

56.7 

56.4 

29.8 

39.2 

53.7 

48.5 

35.1 

 45.1 

 29.1 

 33.8 

0.70 

0.50 

0.59 

0.74 

0.58 

0.74 

0.54 

0.50 

0.37 

0.61 

0.67 

0.67 

0.70 

0.60 

0.61 

 0.49 

 0.70 

 0.59 

42.8 - 46.3 

59.1 - 62.0 

 32.1 - 34.6 

44.0 - 45.7 

63.6 - 66.3 

29.2 - 32.3 

48.1 - 51.3 

61.1 - 63.4 

36.9 - 38.6 

35.3 - 38.0 

30.7 - 32.5 

41.1 - 44.0 

44.9 - 46.9 

51.7 - 54.0 

31.9 - 34.8 

44.0 - 46.2 

32.3 - 35.2 

35.0 - 32.8 

35.0 - 36.9 

56.0 - 57.4 

55.2 - 57.6 

28.5 - 31.2 

37.9 - 40.6 

52.4 - 55.1 

47.3 - 49.8 

33.7 - 36.1 

 44.2 - 46.1 

27.6 - 30.5 

 32.6 - 34.9 

2.04 

1.26 

: 

1.77 

: 

1.40 

2.14 

3.40 

1.26 

0.02 

2.3 

1.13 

0.77 

0.87 

0.97 

0.78 

: 

1.06 

1.31 

1.31 

: 

: 

1.17 

1.10 

1.00 

: 

 1.92 

: 

: 

NO 
(1) Coefficient of variation instead of design effect.  

2 769 

(2) Figures refer to the population aged 16 and over.  

: Information not available. 

Quality report of the second wave of the European Health Interview survey 

37 

 
 
 
 
 
 
 
Table 17 provides the estimates, the standard errors, the 95 % confidence limits and the design effect for the 
proportion of respondents aged 15 years or over that were severely limited in activities people usually do 
because of health problems for at least the past 6 months (HS3).  

Quality assessment 

5 

Table 17. Sampling errors — Respondents aged 15 years or over that were severely limited in activities 
people usually do because of health problems for at least the past 6 months (HS3) 
Estimated 
proportion — p 

Number of 
respondents — n 

95 % confidence 
interval 

Standard 
error — SE 

Design effect — 
deff 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR (1) 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK (2) 

IS 

NO 

371 

466 

816 

335 

24 555 

597 

448 

1 063 

1 434 

1 183 

611 

1 190 

481 

7 069 

491 

291 

548 

310 

488 

968 

24 156 

1 698 

652 

500 

709 

6 030 

421 

1 882 

576 

467 

6.1 

6.4 

8.9 

5.5 

5.9 

10.5 

3.7 

10.3 

6.0 

7.8 

10.5 

7.8 

8.4 

10.4 

7.9 

7.6 

9.2 

6.8 

6.4 

7.0 

7.4 

8.4 

3.1 

8.3 

11.3 

6.3 

7.5 

7.6 

14.1 

6.0 

0.40 

0.30 

0.36 

0.30 

0.19 

0.40 

0.57 

0.40 

0.19 

0.25 

0.44 

0.20 

0.40 

0.30 

0.33 

0.43 

0.35 

0.39 

0.28 

0.30 

0.18 

0.30 

0.18 

0.41 

0.42 

0.30 

0.33 

0.22 

0.60 

0.30 

5.3 - 7.0 

5.7 - 7.1 

8.2 - 9.7 

 4.9 - 6.1 

5.5 - 6.3 

9.7 - 11.3 

2.5 - 4.2 

9.5 - 11.1 

5.2 - 6.0 

7.3 - 8.3 

9.7 - 11.4 

7.4 - 8.2 

7.6 - 9.2 

9.7 - 11.0 

7.2 - 8.5 

6.7 - 8.4 

8.5 - 9.9 

6.0 - 7.6 

6.9 - 5.9 

6.5 - 7.6 

7.0 - 7.7 

7.8 - 9.0 

2.8 - 3.5 

7.6 - 9.1 

10.5 - 12.1 

5.6 - 6.9 

6.8 - 8.1 

 7.1 - 7.9 

13.0 - 15.2 

5.4 - 6.6 

2.12 

1.28 

1.04 

: 

1.64 

: 

1.49 

1.53 

1.53 

1.33 

0.04 

1.16 

1.00 

0.72 

0.81 

1.02 

0.84 

: 

1.05 

1.47 

1.16 

: 

: 

1.34 

0.96 

1.00 

: 

1.42 

: 

: 

(1) Coefficient of variation instead of design effect.  

(2) Figures refer to the population aged 16 and over.  

: Information not available. 

Quality report of the second wave of the European Health Interview survey 

38 

 
 
 
 
 
 
 
 
Table 18 provides the estimates, the standard errors, the 95 % confidence limits and the design effect for the 
proportion of respondents aged 15 years or over declaring having been hospitalized in the past 12 months 
(HO1).  

Table 18. Sampling errors — Respondents aged 15 years or over declaring having been hospitalized in the 
past 12 months (HO1) 

Quality assessment 

5 

Estimated 
proportion — p 

Standard error 
— SE 

95 % confidence 
interval 

Design effect 
— deff 

Number of 
respondents — 
n 
851 

701 

973 

537 

24 709 

549 

1 177  

904 

2 150 

1 851 

591 

2 186 

427 

7 077 

729 

461 

788 

388 

656 

2 293 

24 156 

1 709 

818 

701 

734 

6 117 

530 

1 929 

355 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR (1) 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK (2) 

IS 

9.7 

10.0 

11.8 

 8.4 

15.2 

 9.8 

10.9 

9.7 

9.0 

12.1 

10.6 

8.4 

8.0 

11.6 

12.8 

11.7 

13.3 

8.7 

8.3 

14.8 

12.4 

9.2 

4.2 

11.1 

12.1 

9.9 

9.0 

 8.3 

 8.5 

9.4 

0.40 

0.40 

0.45 

 0.37 

0.26 

 0.40 

0.39 

0.40 

0.23 

0.29 

0.46 

0.20 

0.40 

0.40 

0.45 

0.52 

0.43 

0.44 

0.32 

0.30 

0.24 

0.35 

0.25 

0.42 

0.44 

0.40 

0.36 

 0.24 

 0.40 

 0.37 

8.8 - 10.6 

9.1 - 10.7 

10.9 - 12.7 

 7.7 - 9.1 

14.7 - 15.7 

 9.0 - 10.6 

10.0 - 11.8 

8.9 - 10.4 

8.3 - 9.2 

11.5 - 12.6 

9.7 - 11.5 

8.1 - 8.8 

7.2 - 8.8 

11.0 - 12.3 

11.9 - 13.7 

10.6 - 12.7 

12.5 - 14.2 

7.8 - 9.6 

8.9 - 7.7 

14.1 - 15.4 

11.9 - 12.9 

8.5 - 9.9 

3.7 - 4.7 

10.3 - 11.9 

11.2 - 13.0 

9.2 - 10.7 

8.3 - 9.8 

 7.8 - 8.8 

 7.7 - 9.4 

 8.7 - 10.1 

2.07 

1.28 

1.15 

: 

1.29 

: 

1.59 

1.38 

1.52 

1.28 

0.04 

1.25 

1.12 

0.85 

0.93 

1.01 

0.92 

: 

1.05 

1.06 

1.28 

: 

: 

1.11 

1.00 

1.00 

: 

 1.58 

: 

: 

NO 
(1) Coefficient of variation instead of design effect.  

773 

(2) Figures refer to the population aged 16 and over.  

: Information not available. 

Quality report of the second wave of the European Health Interview survey 

39 

 
 
 
 
 
 
 
Table 19 provides the estimates, the standard errors, the 95 % confidence limits and the design effect for the 
proportion of respondents aged 15 years or over who are obese (BMI>=30).  

Table 19. Sampling errors — Respondents aged 15 years or over who are obese (BMI>=30) 

Number of 
respondents — n 

Estimated 
proportion — p 

Standard 
error — SE 

95 % confidence 
interval 

Design effect — 
deff 

Quality assessment 

5

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR (1)

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK (2)

IS 

NO 

1 229 

836 

1 386 

872 

23 791 

1 108 

2 570 

1 361 

3 691 

2 331 

967 

 2 674 

722 

6 384 

944 

600 

1 203 

920 

1 059 

2 162 

21 371 

3 196 

1 581 

1 073 

950 

6 054 

774 

3 615 

718 

1 026 

13.7 

14.8 

18.2 

 15.1 

16.9 

 19.6 

 28.1 

17.4 

16.0 

14.2 

19.0 

10.7 

13.1 

21.3 

17.3 

15.1 

21.2 

26.1 

14.3 

14.7 

17.2 

16.4 

9.3 

18.6 

15.9 

18.9 

13.4 

 20.1 

 19.0 

 12.9 

(1) Coefficient of variation instead of design effect.  

(2) Figures refer to the population aged 16 and over. 

: Information not available. 

0.60 

0.60 

0.56 

 0.49 

0.36 

 0.60 

0.56 

0.60 

0.34 

0.31 

0.60 

0.24 

0.50 

0.50 

0.51 

0.57 

0.53 

0.76 

0.41 

0.40 

0.29 

0.40 

0.48 

0.52 

0.50 

0.50 

0.44 

 0.41 

 0.40 

0.44 

12.7 - 14.9 

13.6 - 15.9 

18.1 - 20.4 

 14.1 - 16.0 

16.2 - 17.6 

 18.5 - 20.6 

26.8 - 29.4 

16.3 - 18.5 

15.6 - 16.9 

13.6 - 14.8 

17.8 - 20.2 

10.2 - 11.2 

12.2 - 14.1 

20.4 - 22.3 

16.4 - 18.2 

14.0 - 16.2 

20.2 - 22.3 

24.6 - 27.6 

15.1 - 13.5 

13.9 - 15.4 

16.7 - 17.8 

50.3 - 52.3 

8.4 - 10.3 

17.6 - 19.6 

15.0 - 16.9 

17.9 - 19.9 

12.5 - 14.2 

19.3 - 20.9 

 17.7 - 20.3 

 12.1 - 13.8 

2.26 

1.55 

1.15 

: 

2.14 

: 

1.66 

1.66 

1.84 

1.21 

0.03 

 1.52 

1.06 

0.88 

0.92 

0.99 

: 

: 

1.06 

1.41 

1.24 

: 

: 

1.07 

1.02 

1.00 

: 

 1.78 

: 

: 

Quality report of the second wave of the European Health Interview survey 

40 

Quality assessment 

5

5.2.3. Non-sampling errors 

COVERAGE ERRORS 

Coverage errors arise due to divergences between the target and the frame population; they may be due to 
under-coverage (i.e. the frame population does not include all units of the target population), over coverage (i.e. 
the frame population includes units that do not belong in the target population) and misclassification (i.e. unit in 
the frame population which belong to the target population but are wrongly classified).  

Table 20 summarises the information provided by countries on the coverage errors, in terms of the quality of the 
sampling frame, over-coverage and under coverage. 

In some countries, certain population groups were excluded even though they belong to the sampling frame. In 
detail, persons with a protected address (Denmark), homeless people and persons with no permanent address 
(Estonia, the Netherlands, Portugal, Finland) were not covered. Particularly in Germany, Cyprus, Latvia, 
Luxembourg, the Netherlands and Sweden, persons for whom language was a barrier were excluded even 
though they would belong to the target population. Blind persons (Germany) and persons with hearing problems 
(Iceland) could not be captured due to the mode of data collection used. Additionally, the United Kingdom 
mentioned that about 80 % of the sample was initially contacted for a telephone interview and thus there is a risk 
that some potential respondents have not been reached.   

Table 20. Under-coverage, over-coverage and overall assessment of the quality of the sampling frame in 
EHIS wave 2 

Under-
coverage 

Over-
coverage 

Overall quality of the sampling frame 

BE 

: 

Unknown 
but quite 
limited 

Trimestral samples were selected to reduce the lag between last update of 
the register and the moment of actual sampling. Non-registered households 
were not covered. 

BG 

0.5 % 

0 % 

CZ 

1.3 % 

10.0 % 

DK 

<1.0 % 

0 % 

DE 

≈0 % 

0 % 

The  2011  population  census  data  was  used  as  sampling  frame.  Data  on 
deceased  and  emigrants  were  removed  based  on  demographic  statistics 
has been used for updates. 

About  10  %  of  sampling  units  are  considered  useless  since  they  are  non-
residential, e.g. temporarily empty flats, or recreational or commercial space. 
About 1.26 % of selected residential dwellings are dropped from the sample 
for practical reasons. 

Sampling and coverage errors were not an issue in the survey. The Danish 
Civil  Registration  System,  which  is  of  very  high  quality,  is  used  to  obtain 
data. 

Minimal time lag between last update of the sampling frame and the moment 
of actual sampling is achieved due to constant update of the local registries. 
Geographical coverage is guaranteed.  

<1.0 % 

3.0-4.0 %  Good  quality;  three  months’  time  lag  between  last  update  of  the  sampling 

frame and the moment of actual sampling. 

EE 

IE 

0 % 

0 % 

EL 

1.5 % 

0 % 

ES 

0 % 

0 % 

FR 

<5.0 % 

: 

A time lag of approximately 30 months between last update of the sampling 
frame  and  time  of  actual  sampling.  Well  covered  geographical  coverage 
across the country. 

The  2011  population  census data  was somehow  outdated thus  resulting in 
housing  units  found  to  be  empty  or  to  be  used  for  other  purposes  (e.g. 
secondary  residences,  etc.).  Based  on  the  Census  2011,  the  estimated 
undercoverage of the target population is 1.46 %, referring to individuals in 
collective living quarters. 

The  sampling  frame  used  was  a  list  of  dwellings  from  the  2013  population 
register. The percentage of empty dwellings is estimated to be about 10 %. 
The sample size was increased to compensate for the empty dwellings. 

The  ESPS  sample  doesn’t  cover  institutionalized  people,  people  living  in 
overseas  territories  and  non-French  speaking  people.  For  the  rest,  people 
who live in a household of which none of the senior members is insured by 
one  of  the  scheme  of  the  ESPS  scope  are  not  covered.  That  accounts  for 
less  than  5  %  of  the  target  population.  Sickest  and  poorest  people  are 

Quality report of the second wave of the European Health Interview survey 

41 

Quality assessment 

5

Under-
coverage 

Over-
coverage 

Overall quality of the sampling frame 

under-covered as in all the general population surveys. Illiterate people are 
under-covered because of the self-administered mode. 

: 

7.6 % 

Since the 2011 population census was used as sampling frame, households 
created after 2011 are not well represented.  

<1.0 % 

<1.0 % 

Households  were  selected  from  the  LAC  (Liste  Anagrafiche  Comunali) 
register  of  households  which  was  updated  on  January  2015.  The  time  lag 
between the last update of the sampling frame and the moment of the actual 
sampling  was  six  months.  The  frame  might  contain  errors,  such  as 
addresses  (e.g.  due  to  recent  change  of  the  address),  wrong  registers 
(recent  emigration)  and  missing  registers  (recent immigration).  The sample 
excluded institutionalized persons. 

0 % 

10.2 % 

The 2011 population  census was used as sampling frame. Thus, dwellings 
built between October 2011 and August 2014 were covered. 

: 

3.5 % 

HR 

IT 

CY 

LV 

Requirements  of  the  EU  Regulation  and  EHIS  wave  2  manual  were 
followed. 
Shortcomings in terms of timeliness (e.g. time lag between last update of the 
sampling  frame  and  the  moment  of  the  actual  sampling),  geographical 
coverage,  coverage  of  different  subpopulations  (institutionalised  persons), 
multiple listings, etc.). The information from the Demographic Statistics Data 
Processing System was used to create the base for the sampling frame. The 
information  from  population  statistics  and  population  census  was  used  to 
adjust  the  base  (by  excluding  the  persons  who  most  likely  are  not  the 
residents  of  Latvia).  The  time  lag  between  last  update  of  the  population 
frame and the moment of the actual sampling is 12 days. All administrative 
territories are covered by the frame. Institutionalised persons do not belong 
to  the  target  population,  so  they  were  excluded  from  the  population  frame 
(according  to 
the  available  information).  Multiple  listings  of  persons 
practically are not possible as persons are identified by the unique personal 
ID code and one person can hold only one personal ID code. 

The sampling frame was made up using the population register. The register 
is updated regularly. The sampling frame used was updated one month prior 
the  fieldwork.  Additional  information  of  deaths  was  available  during  the 
fieldwork.  It  covered  the  whole  population  of  the  country.  Persons  living  in 
collective  households  and  institutions  were  not  covered.  In  order  to  adjust 
for under-coverage, calibration of sampling weights using the known values 
of age, sex and urban/rural place of residence has been applied. 

With 95 % population coverage, the National Health Insurance Database is 
considered as the most complete list of inhabitants available in Luxembourg. 
The  5  %  remaining  people  are  identified  as  being  employees  of  the 
European  Commission  who  have  their  own  health  insurance  system  and 
asylum seekers who just arrived and are on the way to be registered. 

Acceptable  timeliness  and  geographical  coverage.  The  rate  of  over-
coverage  is  about  3%  (including  emigrants,  institutionalised  persons). 
Selected  addresses  could  not  be  located  for  about  0.7  %  of  all  cases  and 
the selected persons could not be located in the available address for about 
9 % of all cases. 

The national population register from which the sample was drawn is based 
on the 2011 Census updated with deaths (monthly) and births. The time lag 
between  census  and  sampling  may  reduce  the  quality  of  contact  data, 
however  efforts  were  made  to  collect  updated  contact  details.  The  sample 
was drawn from a national population register with complete coverage of the 
total  target  population.  The  register  is  based  on  census  population  data 
updated with births and deaths. Updates are done monthly for deaths while 
for  other updates  are  carried  out  less  frequently.  In  general,  coverage  is 
good. The last census was conducted in 2011 so the time lag between the 
census  and  the  moment  of  the  actual  sampling  may  result  to  changes  in 
household contact details. 

The  Basic  Municipal  Registry  (in  Dutch  Basisregistratie  Personen,  BRP)  is 
used  as  the  sample  frame.  This  register  contains  all  persons  who  are 
registered  in  municipalities,  excluding  the  Caribbean  Islands.  Persons 
belonging to institutional households are excluded from the sampling frame 

LT 

4.0 % 

1.0 % 

LU 

0 % 

0 % 

HU 

0.4 % 

~3.0 % 

MT 

: 

: 

NL 

0.2 % 

<0.3 % 

Quality report of the second wave of the European Health Interview survey 

42 

Quality assessment 

5

Under-
coverage 

Over-
coverage 

Overall quality of the sampling frame 

(and  from  the  population).  The  sampling  frame  is  updated  once  a  month. 
Immigrants and newborns are added to the frame, emigrants and deceased 
persons are deleted, and data are updated for persons who have moved to 
a different address. When a sample is selected, the names and addresses 
of  the  intended  respondents  are  not  known.  This  has  to  be  retrieved  from 
the BRP. This is done at most six weeks before the start of the fieldwork. 

0 % 

0 % 

The overall quality is considered to be very good and is constantly updated. 
The sampling frame covers the whole Austrian population. 

≈0 % 

0 % 

11.8 % 

10.5 % 

The register of addresses is used as the sampling frame. 

AT 

PL 

PT 

SI 

SK 

RO 

0.4 % 

6.3 % 

FI 

≈0 % 

0 % 

SE 

0 % 

0 % 

UK 

2.0 % 

10.0 % 

0 % 

0 % 

The Central Population Register is used as a sampling frame. Its coverage 
is considered as good. 

: 

: 

The  sampling  frame  was  selected  from  the  National  Dwellings  Register 
(NDR)  which  comprises  all  private  dwellings  registered  in  the  2011 
population  census.  The  frame  is  updated  continuously  based  only  on  the 
information coming from other surveys. The geographical coverage refers to 
the  total  territory,  however  the  population  living  in  collective  dwellings  or 
institutions (approximately 1 % of total population) is excluded. 

The  master  sample  EMZOT  used  as  a  sampling  frame  is  periodically 
updated  from  results  of  population  surveys  and  the  results  of  the  micro 
census.  From  the  selected  dwellings  6.3  %  were  ineligible  (seasonal  or 
demolished).  All  the  country  is  covered.  Institutionalised  persons,  persons 
who  had  their  usual  residence  for  the  last  year  at  another  address  in  the 
sample are excluded. 

The  sampling  frame  has  not  been  updated  since  2011,  when  the  last 
population  census  was  performed.  It  consists  of  all  dwellings,  divided  into 
occupied,  not  occupied  and  institutionalised  households.  Dwellings  that 
appear not to be part of the target population or incorrectly recorded are not 
considered in the sample selection. 

The  Population  Register  Centre  Finland  is  used  as  sampling  frame  and  is 
continuously kept up to date and it covers the population as a whole. People 
in  institutional  care  and  without  a  permanent  address  were  removed  from 
the sampling frame. 

Excellent quality of the sampling frame. The update of addresses was made 
at the time the survey took place and thus recently updated information was 
available for all individuals. 

98 % of individuals living in private households in the entire geographic area 
of the United Kingdom are included in the postcode address file (PAF) which 
is  updated  regularly.  The  PAF  does  not  cover  institutionalized  individuals 
who  however,  are  not  in  the  target  population  of  EHIS.  To  limit  over-
coverage,  “delivery  points”  which  receive  a  large  amount  of  mail  are 
assumed  as  businesses  and  excluded.  Even  after  this  step,  approximately 
10 % of the sampled addresses are typically ineligible, either because they 
contain  businesses,  are  vacant,  or  are  inhabited  by  individuals  outside  the 
target  population.  Out-of-scope  households  were  fairly  limited  where  the 
LFS  was  used  as  a  frame,  as,  for  example,  businesses  will  already  have 
been excluded by the LFS. There will, however, be some households where 
individuals  have  moved  out.  The  sample  was  increased  to  account  for 
anticipated over-coverage. 

IS 

NO 

: 

: 

: Information not available. 

: 

No shortcomings in the sampling frame. 

1.8 % 

No shortcomings in the sampling frame. The Norwegian Central Population 
Register (CPR) is of high quality. 

Quality report of the second wave of the European Health Interview survey 

43 

Quality assessment 

5

MEASUREMENT ERRORS 

Measurement errors occur during the data collection and cause the recorded values of variables to be different 
from the true ones. Proxy interviews, i.e. when a person provides answers on another person’s behalf, is a cost-
effective solution, however, is one of the potential error sources that may contribute to measurement errors. 
According to the methodological guidelines, proxy answers in EHIS could be allowed for some questions only 
and in cases where the respondent was unable to answer for one or more of the following reasons:  

1. Suffering from long term cognitive impairment

2. Suffering from long term severe debilitation

3. Suffering from a long term sensory impairment that prevents the interaction between interviewer and

interviewee

4.

In hospital / health or social care facility for the entire period of the fieldwork

5. Away from the household for educational or work purposes for the entire period of the field work in their area

of residence

6. Other reason

Proxy interviews were not allowed at all in Denmark, Germany, Estonia, Ireland, Luxembourg, Hungary, the 
Netherlands, Portugal, Slovakia and Sweden as well as Norway and Iceland (see Table 21 and Figure 6).  

Quality report of the second wave of the European Health Interview survey 

44 

Table 21. Proxy interviews and reasons for proxy usage in EHIS wave 2 
Part  of  the  questionnaire  for  which 
proxy usage was allowed 

Proxy interviews 
allowed 

Reasons for proxy usage 

Quality assessment 

5

BE (1)

BG 

CZ 

DK 

DE 
EE (2)

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK 

IS 

Yes 

Yes 

Yes 

No 

No 

No 

No 

Yes 

Yes 

Yes 

Yes 

Yes 

Yes 

Yes 

Yes 

No 

No 

Yes 

No 

Yes 

Yes 

No 

Yes 

Yes 

No 

Yes 

No 

Yes 

No 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5, 6 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5, 6 

- 

- 

- 

- 

- 

- 

- 

- 

Whole questionnaire 

Whole questionnaire 

1, 2, 4, 5 

1, 2, 3, 4, 6 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5, 6 

Whole questionnaire 

1, 2, 3, 4, 5, 6 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

Limited to questions specified in guidelines 

1, 2, 3 

- 

- 

Whole  questionnaire  except  HS1,  PC3, 
HA3, PN1, PN2, MH1a-h, UN1, UN2, SS1-
SS3, IC1-IC3, AL1-AL6 

- 

- 

- 

1, 2, 3, 6 

Limited to questions specified in guidelines 

1, 2, 3 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

- 

Limited to questions specified in guidelines 
and to questions not related to tobacco and 
alcohol consumption 

1, 2, 3, 4, 5 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

- 

Whole questionnaire 

- 

6 

- 

Limited to questions specified in guidelines 

1, 2, 3, 4, 5 

- 

- 

NO 
(1) Proxies were not allowed for specific modules of the face-to-face questionnaire and for the whole self-administered questionnaire. 

No 

- 

- 

(2) A proxy response was permitted only in an exceptional case where the selected respondent was in the final stage of disease.  

- Proxy usage not allowed. 

Regarding reasons for using proxy, most countries declared that proxy interviews were used for all five reasons 
mentioned above with the exception of Lithuania and Austria, where proxy was allowed only in the cases in which 
the respondent was not able to reply, i.e. reasons 1, 2 and 3. Moreover, in Belgium proxy interviews were also 
allowed in cases that the selected person refused to reply. Instead, in Spain and Malta, proxy interviews were 
used in cases that the selected person did not speak Spanish and Maltese or English respectively, while in Latvia 
proxies were used for persons in the army and sailors. In Italy, proxies were used when persons were too old and 
needed help, had language difficulties or were not willing to reply. Also, in Slovenia proxies were only allowed in 

Quality report of the second wave of the European Health Interview survey 

45 

Quality assessment 

5

cases where respondents suffered from long-term cognitive or sensory impairment, severe deliberation, or were 
in hospital, health or social care facility or were away from the household for educational or work purposes for the 
entire period of fieldwork. Finally, in Finland, proxies were used when the selected persons or their caregivers 
considered it necessary. Moreover, in Belgium, proxy use was not permitted for specific sensitive questions, 
while in Romania, proxy was not allowed for questions related to alcohol and tobacco consumption.    

Figure 6. Countries in which proxy interviews were allowed in EHIS wave 2 

As Figure 7 shows, the percentage of proxy interviews varied significantly across countries, from 13.4 % in 
Belgium to 1.1 % in Romania and 0.5 % in Austria. 

Figure 7. Percentage of proxy interviews in EHIS wave 2 
(%) 

Note: Proxy interviews were not allowed in Denmark, Germany, Estonia, Ireland, Luxembourg, Hungary, the Netherlands, Portugal, Slovakia, 

Sweden, Iceland and Norway.  

Source: Calculations based on national EHIS microdata files, national quality reports. 

Quality report of the second wave of the European Health Interview survey 

46 

BE, BG, CZ, EL, ES, FR, HR, IT, CY, LV, LT, MT, AT, PL, RO, SI, FI, UKDK, DE, EE, IE, LU, HU, NL, PT, SK, SE, IS, NOAllowedNot allowed02468101214BelgiumItalyBulgariaUnited KingdomPolandFinlandCroatiaCyprusLatviaGreeceSpainCzech RepublicMaltaSloveniaLithuaniaFranceRomaniaAustria(%)Quality assessment 

5

NON-RESPONSE ERROR 

Non-response is the failure of a survey to collect data on one or more survey variables, from the population units 
designated for data collection. The difference between the statistics computed from the collected data and those 
that would be computed if there were no missing values is the non-response error.  

There are two types of non-response: 





unit non-response which occurs when no data are collected about a selected population unit;

item non-response which occurs when data only on some but not all survey variables are collected about a

selected population unit. 

Unit non-response 

Figure 8 presents the unit non-response rates at national level. The unweighted unit response rate was 
computed as the number of respondents to the sum of the number of eligible sample population and unresolved 
units. 

The unit non-response rate was derived as: 1–response rate. 

Figure 8. Unit non-response rate in EHIS wave 2 (in %) 

(1) The non-response rate concerns only to face-face interviews (before substitutions). 

(2) The non-response rate was derived based on figures referring to households. 

(3) The figure refers to the total non-response rate. Unit non-response rate for face-to-face interviews was 38.6%, for telephone interviews was 

41.5 % and 51.9 % for Northern Ireland. 

Source: Reported unit non-response rates, calculations based on information provided in national quality reports. 

Quality report of the second wave of the European Health Interview survey 

47 

01020304050607080IcelandNorwayCyprus (²)PortugalRomania (²)GreeceItaly (²)LithuaniaCroatia (²)Spain (²)(⁴)SlovakiaBulgariaCzech RepublicEstonia (⁵)LatviaHungarySloveniaIrelandNetherlandsUnited Kingdom (²)(³)SwedenPoland (²)Belgium (¹)(²)France (²)MaltaDenmarkFinlandAustriaGermany (⁴)Luxembourg(%)Quality assessment 

5

The reported unit non-response exceeded 50 % in five countries (Denmark, Germany, Luxembourg, Austria, 
Finland), while in Cyprus and Portugal the respective rate was less than 10 %. 

It should be mentioned that it recorded its highest values in countries that solely used a self-administered mode 
of data collection (e.g. Denmark, Germany, Luxembourg, Finland). In the Netherlands, non-respondents to the 
web self-administered questionnaire were contacted for a face-to-face interview in order to reduce the high non-
response rate (71.5 %).  

In some countries, high non-response was recorded for certain subgroups of the population: elderly people in 
Austria, men and young persons in Finland and Sweden, illiterate or seriously sick people or non-French 
speakers, young people and employed population in urban areas in France, young people in the Czech Republic. 

Map 1 shows a clustering of countries into four groups based on their unit non-response rates. 

Map 1. Unit non-response rates in EHIS wave 2 (in %) 

Source: Reported unit non-response rates, calculations based on information provided in national quality reports. 

Methods used for reducing unit non-response 

All countries sent in advance notification letters to the selected respondents, two to four weeks prior to the launch 
of the data collection and made multiple attempts to contact the selected respondents either by phone or through 
personal contacts at the doorstep at different times and days. On average, three to five subsequent reminders 
were made.  

In Cyprus and Greece, if the interviewer could not establish contact with the interviewee in the first visit then a 
leaflet was left at the door with information on the next visit. The interviewer’s telephone was also enclosed so as 
to arrange for an appointment for interview in case the interviewee could not be at home at the day and time of 
the next visit. In the case of Greece, substitution of the household member that could not be reached was 
allowed, although not recommended. In Spain, the fieldwork period was extended by two weeks and in Croatia 
proxy response was allowed if the respondent was absent for the entire period of the fieldwork. In Lithuania, 
persons selected to participate in any social survey are not selected in consecutive surveys in order to reduce the 
response burden. In the Netherlands and Sweden, two reminders were sent; non-respondents were then 
approached for a face-to-face and telephone interview, respectively. In Slovakia and Poland, survey promotion 

Quality report of the second wave of the European Health Interview survey 

48 

Quality assessment 

5

has been conducted, whereas incentive strategies were applied (Germany) and promotional presents were given 
(Slovakia) to motivate respondents.  

Additionally, in three countries (Belgium, Greece and Lithuania) substitutions were made in case of unit non-
response. In Belgium, all non-respondents have been substituted (45.4 %), in Greece, persons who were 
temporarily absent, who denied participating and proxy interviews were not possible were substituted (0.46 %), 
while in Lithuania, persons that could not be contacted were substituted (9.2 %).  

Item non-response 

Table 22 presents the reported item non-response rates (unweighted and before imputation) for the health 
variables as well as the total unweighted item non-response, followed by a list of variable with the highest 
reported item response rate among those variables with an item non-response rate greater than 10 %. 

Bulgaria, Denmark, Ireland, Hungary and Finland reported an item non-response rate greater than 10 % for more 
than ten EHIS variables. 

The “Net monthly equivalised income of the household” (HHINCOME) variable recorded high non-response rates 
in many countries. Denmark, Estonia, Spain, France, Croatia, Luxembourg, Poland and Slovenia reported an 
item response rate that was below 90 % for HHINCOME, while Austria, Greece, Cyprus and Belgium stated that 
no difficulties were met in the recording of the variable. 

Most countries did not apply item imputation with the exception of Belgium, Germany (for HHINCOME), Ireland, 
Italy, Latvia, Lithuania, Hungary, Austria, Romania and the United Kingdom. 

Table 22. Summary information on the item non-response rates (unweighted and before imputation) in EHIS 
wave 2 

Item non-response rate across 
health variables (unweighted 
and before imputation) (%) 

Min 

Average 

Max 

Total item 
non-
response (%) 
(unweighted) 

Number of 
variables with 
item response < 
90 % 

Variables with the 
highest item non-
response rate among 
those with a rate >10 % 

BE 

BG 

CZ 

0 

0 

0 

5.6 

6.3 

0.5 

: 

15.6 

0.7 

DK 

0.1 

4.6 

34.2 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

0 

0 

0 

0 

0 

1.8 

0.1 

6.4 

0 

0.3 

15.4 

4.8 

37.8 

0 

3.0 

0.4 

3.6 

25.3 

0.1 

1.5 

10.2 

0 

0 

1.4 

0 

7.8 

0 

: 

8.8 

0.1 

4.6 

2.5 

2.2 

7.9 

0 

0.3 

3.6 

3.2 

1.2 

: 

: 

55 

0 

12 

2 

5 

25 

0 

1 

10 

5 

0 

0 

: 

MH1F (15.6 %) 

- 

HH_ACT, HH_INACT, 
HHINCOME, AM6B, AC2, 
PC2, PC3, HA3, HO2, 
HO4, PE5, IC3 

PL4, PL5 

HH_ACT, HH_INACT, 
MARSTADEFACTO, 
HHINCOME 

HO1 (37.8 %) 

- 

HHINCOME (19.9 %) 

PC2, HA2, PE3, PE5, 
PE7, FV2, FV4, CITIZEN, 
HHINCOME, UN 

MARSTADEFACTO, HH_
ACT, HH_INACT, HHINC
OME, AM5 

- 

- 

Quality report of the second wave of the European Health Interview survey 

49 

Item non-response rate across 
health variables (unweighted 
and before imputation) (%) 

Min 

Average 

Max 

Total item 
non-
response (%) 
(unweighted) 

Number of 
variables with 
item response < 
90 % 

Variables with the 
highest item non-
response rate among 
those with a rate >10 % 

Quality assessment 

5

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI (1)

SK 

FI 

SE 

UK 

IS 

0.1 

0.1 

0.1 

0 

0 

0 

0 

0 

0 

0 

0 

0 

1.0 

1.0 

0 

0 

2.4 

0.1 

2.9 

17.1 

4.1 

16.8 

0.1 

1.5 

0.5 

0.5 

: 

0.1 

0.2 

0.1 

: 

0 

13.1 

10.5 

9.4 

44.0 

2.1 

1.3 

47.5 

1.0 

2.2 

0.2 

3.0 

: 

0.4 

0.7 

0.4 

0.8 

0.3 

: 

: 

0.1 

12.7 

17.4 

16.8 

1.9 

0.2 

0.9 

1.9 

4.7 

6.2 

3.1 - 7.8 

5.3 

0.8 

4 

0 

6 

15 

1 

1 

0 

1 

0 

0 

: 

0 

19 

5 

0 

0 

IN1 (58.6 %), AM1 (12.3 
%), SS2 (13.0 %), SS3 
(17.1 %) 

- 

PE4, PE5, UN1B, 
HHINCOME, HH_ACT, 
HH_INACT 

MH1A, MH1F, AM1, PA1, 
PA3, PA5, PA8, BMI1, 
BMI2, PE1, PE3, AL1, 
SS2, SS3 

BMI2 (13.2 %) 

PA4 

- 

HHINCOME (19.6 %) 

- 

- 

HHINCOME 

- 

PA1, HH_ACT, 
HH_INACT, PN2, CD1 

AC1A, AC1B, AC1C, PL4, 
PL5 

- 

- 

NO 
(1) Questions for activity status of the persons in the household were not raised and thus the reference variables HH_ACT and HH_INACT 

0.9 

0.5 

9.2 

0 

0 

- 

recorded the highest item non-response rates.  

: Information not available; - No variables with a rate >10 %. 

Figure 9 shows the number of countries per EHIS variable for which the item non-response rate was higher than 
10 %.  

The variables that recorded in more than nine countries an item non-response rate greater than 10 % were 
“Need to receive help or more help with one or more self-care activities” (PC3), “Time spent on doing sports, 
fitness or recreational physical activities in a typical week” (PE7), “Time spent on bicycling to get to and from 
places on a typical day” (PE5), “Need for help or more help with one or more domestic activities” (HA3) and “Net 
monthly equivalised income of the household” (HHINCOME). 

Quality report of the second wave of the European Health Interview survey 

50 

Figure 9. Number of countries for which the item non-response rate was higher than 10 % 

Quality assessment 

5 

Source: Calculations based on national EHIS microdata files. 

Quality report of the second wave of the European Health Interview survey 

51 

131312119888877766666665555555444444444444444444444444444333333333332222222222222222222111111111111111111102468101214PC3PE7PE5HA3HHINCOMEAL2AL3AW2IC3AL4AL5PE3AL6HH_ACTHH_INACTPE4PE6PN2UN1BAL1FV2FV4PA1PA5PE8UN2DAM5BM1FT_PTHA2IC2MH1AMH1BMH1CMH1DMH1EMH1FMH1GMH1HPA3PA4PA6PA7PA8PE1PE2PL5SK4SS3UN1AUN2AUN2BUN2CAM3AW1HS1IC1JOBISCOPA2PC2PL4PN1SS1SS2BM2CD1ACD1BCD1CCD1DCD1FCD1GCD1ICD1JCD1KCD1LCD1MCD1NCD1OFV1FV3MARSTADEFACTOMD1MD2AC1AAC1BAC1CAC2AM6BAM7BIRTHPLACECD1HCITIZENDEG_URBHATLEVELHO1HO3HS2HS3JOBSTATPL6PL7SK1Quality assessment 

5

PROCESSING ERROR 

During the data collection process, data must undergo a certain processing: coding, data entry, data editing, 
imputation, etc. Errors introduced at these stages of the data collection process are called processing errors. 

The processes adopted by countries for the data entry and coding control, the main errors detected and methods 
used for data cleaning and the methods of post-codification of open questions are, in summary, described below. 

Regarding the data entry and coding control process, where a non-electronic data collection mode was used, 
data entry has been applied either by interviewers or by the staff of the regional statistical offices. In most cases, 
data coding was either done manually or using scanning.  

The main errors detected were codification errors of questions on occupational (JOBISCO) and economic 
activities (LOCNACE) as well as of open questions. In most countries where an electronic mode of data 
collection was used, consistency checks were embedded in the questionnaire and thus data entry or coding 
mistakes were automatically detected and corrected. 

Regarding data validation, Eurostat’s guidelines have been widely applied and in some cases where 
inconsistencies were identified, questionnaires were sent back to interviewers for correction. In some countries, 
additional calls to respondents were made when necessary.    

Open questions were used for recording the status in employment (JOBSTAT), the economic sector of 
employment (LOCNACE) and the occupation in employment (JOBISCO). Apart from these variables, in Spain, 
Croatia and Lithuania, the educational level (HATLEVEL) was also an open question. In Lithuania, post-coding 
was also applied for the place of birth (BIRTHPLACE), the citizenship (CITIZEN), the household income 
(HHINCOME), and the degree of urbanisation (DEGURBA). Post-coding of the questions regarding the place of 
birth (BIRTHPLACE) was applied in Poland, Romania and Slovakia.  

5.3. Timeliness and punctuality 
According to the Commission Regulation, data shall be delivered to Eurostat by 30th September 2015, or 9
months after the end of the collection period in cases in which the survey has been carried out beyond 
September 2015.  

The preparation of the survey started in different time periods across countries. For instance, Belgium, the Czech 
Republic, Estonia, France, Hungary, Slovenia and the United Kingdom started in 2012, Spain, Croatia, 
Luxembourg, the Netherlands, Austria, Poland, Portugal, Romania and Slovakia in 2013, while Bulgaria, 
Germany, Ireland, Greece, Cyprus, Latvia, Lithuania, Malta, Finland, Sweden and Norway started early in 2014.  

The duration of the preparation, data collection and data process phases varied among countries (Figure 10). 
The majority of them provided their data to Eurostat on time (September 2015 or October 2015 at the latest). 
Another interesting point is that some countries (Belgium, Hungary, Lithuania and Austria) disseminated their 
national data before their submission to Eurostat. 

52 

Quality report of the second wave of the European Health Interview survey 

52 

Figure 10. Duration of the preparation, data collection and data processing phases in EHIS wave 2  
(months) 

Quality assessment 

5

5.4. Comparability 

5.4.1. Conceptual deviations 

Table 23 presents the questions which were modified in the implementation. The reported modifications may not 
have essentially impact in the comparability of results. In many cases the implemented adaptations (e.g. splitting 
answer categories or questions, wording modifications to adapt questions according to the specificities of the 
national languages, addition of more examples, etc.) are not envisaged to have major impact on the resulting 
figures.   

Modifications were more frequently introduced to questions regarding preventive services (PA), physical and 
sensory functional limitations (PL), accidents and injuries (AC), use of ambulatory and home care (AM) and 
smoking (SK).  

Table 23. Modifications in the national questions  for EHIS variables in wave 2
Modifications in the questions for EHIS variables in wave 2
AC2, PL6, HO1, AM7, PA1, AL1, AL6 

BG 

CZ 

DK 

EE 

IE 

EL 

ES 

CD1,  PN1,  PN2,  AM4,  AM5,  PA1,  PA5,  PA6,  UN2,  SK1:  Adaptations  included  use  of  routed 
questions,  different  use  of  filters,  small  modifications  in  wording.  Some  introductory  texts  were 
skipped or extra instructions for interviewers were added. 
AM6, MD2, UN2D, PE1, FV1, FV2. PN1: only 5 response categories were included by mistake (and 
not 6 as intended). “Very mild” was not included as response category. 
AC2, HA2, HA3, PA1, AL3, AL5: Modifications were applied to the answer categories. 

HS2, CD1a,c,e,k, AC1a-c, AC2, AW1, AW2, PL3, PL6, PL7, PC1- PC3, HA1, HA3, PN1, PN2, MH1a-
h, HO1-HO4, AM1-AM5, AM6a-b, AM7, PA1-PA8, UN1a-b, UN2a-d, BM2, PE1, PE8, FV1, FV2, FV3, 
SK2, SK3, AL1-AL6, SS1-SS3, IC1- IC3. 

AC2,  PL1,  PC2,  HA2,  MD2,  PA1,  SK1,  SK4:  Modifications  include  different  wording,  added 
subcategories and new questions. No impact on the derived  variables. Questions PA9, PA10, FV5, 
FV6 and SK3.1 were included to cover national needs. 

HS1,  AM1,  AM2,  AM4,  AM7,  PA1-PA8,  PE1,  FV1-FV4,  SK1,  SK4,  AL2-AL5:  Split  of  answer 
categories. 

Quality report of the second wave of the European Health Interview survey 

53 

53 

05101520253035BEBGCZDKDEEEIEELESFRHRITCYLVLTLUHUMTNLATPLPTROSISKFISEUKISNO(months)Preparation of the surveyData collectionData processingQuality assessment 

5

FR 

HR 

IT 

CY 

LV 

LT 

HU 

MT 

NL 

PL 

PT 

RO 

SI 

SK 

Modifications in the questions for EHIS variables in wave 2
Mainly UN module. Minor changes for: HS1-3, CD1, AC1, AC2, AW1, AW2, PL, PC2, PC3, HA1a,f, 
HA2,  HA3,  PN1,  HO2,  HO4,  AM1-3,5,6a,7,  MD1,  PA,  UN,  PE1-7,  FV2,  FV4,  SK1,  SK2,  SK3,  AL, 
SS2, SS3, IC1-3 

PC and HA modules: no filter on age was applied. MH module: a question was added. 

AC2:  Split  into  two  questions to  make clear  the  need  of medical  care  and  the  type  of  medical  care 
needed;  HA1d-g,  AM4:  Examples  were  added;  AM6b:  Split  into  two  types  of  professions  to 
distinguish psychologist, psychotherapist (AM6b) and psychiatrist (AM6c); AM7: the answer “yes” was 
split into 3 categories to distinguish the type of assistance received; PA1: Added category to “yes” to 
know  if  people  have  never  had  a  vaccination  against  flu.  A  filter  has  been  used  to  have  a  specific 
question concerning the month and year when the respondent has been vaccinated in less than two 
years; UN1: “No” was modified to “No, I have got them without delay”; SK1: Answer category “not at 
all”  was  added  to  distinguish  who  have  never  smoked  and  who  smoked  in  the  past;  SK2:  Answer 
category  “Other”  was  not  included  because  it  is  not  adaptable  to  Italian  habits  concerning  tobacco 
product. 

AM2: Added "even telephone consultation" in the wording of the question. PA1: Split into 3 questions 
in order to make the concepts easier for the respondent. PA5, PA6, PA7, PA8: Split into 2 questions 
in order to make the concepts easier for the respondent. 

AC2:  For  answer  category  “Yes,  from  a  doctor  or  nurse”  additional  medical  personal  category 
“physician assistant / fleshier” was added. AM6: categories have been added for national needs. PA6: 
the question was split. 

HO2, AM6b, UN2a, PE2, PE4, PE8, SK2, AL3, AL5, AL6.  Two questions about illegal cigarette and 
strong alcohol purchases were added. 

CD1, AM7, PA1, FV1, FV3, SK1-SK4, AL2-AL5. 

HATLEVEL,  HHTYPE:  increased  number  of  categories,  AM2-AM5:  split  into  questions  related  to 
private and public service provision, PE6: split by intensity of fitness/sport/recreational activity. 

HS3,  CD1c,d,  AC1b,c,  AC2,  AW1,  AW2,  PL1  (derogation  for  PL5-PL6),  PC1a-e,  PC2,  PC3,  HA2, 
HO2-HO4, AM1, AM4, AM6a, PA1-PA8, UN2a-d, PE1-PE8 (Derogation), FV1-FV4, SK1, SK2, AL2-
AL5, AL6 (Derogation), IC1-IC3. 

PA1: major changes, PL2, PL4, PL5, PL7 AM2, AM4, MD2, PE6, SK1, AL3, AL5: minor changes. 

AC1a-c, AC2, AW1, PL2-PL7, PC1a-e, HA1a-g, AM7, PA1-PA8, SK1, SK4. 

AM1,  AM2,  AM4:  answer  categories  were  added;  AM3,  AM5:  answer  category  “never”  was 
introduced; AM6b: the category "Psychologist, psychotherapist or psychiatrist" was more elaborated; 
PA1:  the  specifications  "in  the  last  12  months"  and  "more  than  12  months  ago"  were  highlighted 
separately,  to  explain  the  time-period  the  question  was  referring  to;  PA5,  PA6,  PA7,  PA8:  a  filter 
question for persons who have never performed medical tests has been added; PE2, PE4, PE6, PE8: 
the  answer  category  "Yes"  has  been  added  serving  as  a  filter  for  persons  who  perform  physical 
activities;  PE4,  PE5: examples  of  activities  were included;  AL3,  AL5:  the number of  bottles  /  cans / 
glasses  consumed  was  asked.  During  the  data  analysis,  the  data  collected  were  transformed  in 
grams of pure alcohol, according to the specifications; AL6: imputation was necessary for the answer 
category  "2-3  days  /  month";  SS3:  the  response  category  "Not  applicable  (I  do  not  have  any 
neighbours)" was introduced to diminish the risk of non-response. In the microdata file, this category 
has been reported with the answer category "Very difficult".  

Questions  about  the  household  constitution  were  asked  in  more  questions  (similarly  to  the  data 
delivery guidelines). 

HS01:  the  answer  category  “fair”  was  rephrased  to  “not  good  not  bad”;  AC1: accident  is  into  the 
national  language  was  translated into  two  terms,  which  represent  and cover  the  term  accident;  PN: 
the  wording  of  the  instruction  was  modified  from  “pain  you  have  had”  to  “pain  you  have  felt”;  PL6: 
instead of “half a km”, “500 meters” was used; PC1: the specification relating to “everyday” activities 
was  excluded;  AM  sub-module:  questions  on  the  use  of  ambulatory  and  home  care  activities  were 
divided into two sub-modules; PA1: in case of exact specification of month and year in questionnaire 
we allowed only years 2013 and 2014. Answer category (code) 1 was modified to “in 2012 or earlier”; 
AM2,  AM3:  reference  to  “family  doctor”  was  not  included;  AL3,  AL5,  AL6:  instead  of  “drinks”, 
“standard alcoholic drinks” were asked; AL6: the term “on a one occasion” was translated as “at one 
sitting”; IC1: the term “some age problem, chronic health condition or infirmity” was modified to “some 
old age, longstanding (chronic) illness or health problem or congenital or acquired infirmity”; PE8:  the 
term “such as doing resistance training or  strength exercises” was dropped;  AL:  the term “cocktails 
and premixes” was dropped. 

FI 

Some of  the questions  were  slightly modified  or  combined in  order  to  develop  a clear and  effective 

Quality report of the second wave of the European Health Interview survey 

54 

54 

Quality assessment 

5

Modifications in the questions for EHIS variables in wave 2
postal  questionnaire.  Some  examples  were  also  added.  Also,  some  modifications  had  to  be  done 
because  of  lingual  differences  and  differences  in  national  practices  (e.g.  public  health  care  related 
questions). Derived variables are in line with the conceptual guidelines. 

PA5-PA8: Different grouping than the one required in the specifications for the answer categories for 
the duration. Additional questions on cannabis use, sexual orientation, and e-cigarette use. 

HS1,  CD1a-o,  AC1a-c,  AW1,  PL1-PL7,  PC1a-e,  PC3,  HA1a-g,  MH1a-h,  AM1,  AM6a-b,  AM7,  PA1, 
UN2a-d, BM1, BM2, PE2, PE4-PE8, FV1, FV3, FV4, AL1, AL3, AL5, AL6. 

HS3,  AC2,  PL2,  PL4-PL7,  PC1a-e,  HA1a-g,  PN1,  PN2,  AM1,  AM3,  AM5,  AM6b,  AM7,  MD2.  PA1-
PA8, UN1a-b, UN2a-d, PE4-PE8, SK1-SK4, AL1, AL6, IC3. 

SE 

UK 

NO 

Note: Belgium, Germany, Luxembourg and Austria did not raise any issues. Iceland did not provide specific information. 

5.4.2. Problematic modules or questions 

The most common questions or modules being reported as problematic are the following: 

 Physical activity/exercise (PE): Based on the reports of the countries (Bulgaria, Czech Republic, Croatia,
Latvia, Slovakia) respondents had difficulties in specifying the exact time spent in physical activity 
mainly due to memory effects. Sweden identified misreports in some figures due to self-reporting (e.g. 
minutes instead of hours).  

 Alcohol consumption (AL): Bulgaria, the Czech Republic, Croatia, Italy, Cyprus, Romania and Slovakia

reported that respondents confronted difficulties in quantifying the exact number of drinks consumed. 
France asked for derogation and did not include questions regarding alcohol consumption.   

 Mental health (MH): Spain, Lithuania and Slovakia stated that it was not straightforward for respondents to

describe their mental health status (e.g. melancholia, loss of energy, being very nervous, etc.) and 
understand the conceptual meaning of some answer categories (e.g. feeling down, hopeless, etc.). In 
Bulgaria, the item non-response rate for the “extent of feeling bad about yourself” (MH1F) was relatively 
high (15.6 %). 

 Use of inpatient and day care (HO): In the Czech Republic, difficulties are mentioned for capturing variables
on hospitalisation. EU concepts were difficult to apply in the context of the specificities of the national 
health care system, since one-day hospitalisation is a term not commonly known. Also, Italy mentioned 
that for variables on admissions as a day patient in a hospital” (HO3, HO4) respondents had difficulties 
in understanding the type of the health care needed. In France, a derogation has been requested for 
variables on informal health care. 

 Chronical diseases (CD): Slovakia mentioned that respondents found the relevant questions quite sensitive,
while the Czech Republic reported that respondents could not describe exactly their disease.  

 Preventive services (PA): Irish and Danish respondents had difficulties in providing information about the last
time they had vaccination (PA1a and PA1b), while Slovakia mentioned that the question on last time of 
a mammography was considered sensitive. 



Income (HHINCOME): Respondents were reluctant to provide information for their income in (Estonia,

Cyprus, Greece, Spain, Luxemburg, Latvia, Lithuania and Poland). Additionally, Denmark perceived that 
it was difficult for respondents to provide information on the net monthly income since a self-
administered mode was used, while Ireland imputed the variable using data from EU-SILC. 

5.4.3. Cross-country comparability

The common regulatory framework, variable definitions, conceptual guidelines and the proposed protocol for 
translation serve the basis to ensure comparability of the statistics among the participating countries. The vast 
majority of countries reported that the guidelines and the Commission implementing Regulation on EHIS have 
been adopted and closely followed.  

France stated some methodological deviations in sampling method used, leading to under-coverage of people 

Quality report of the second wave of the European Health Interview survey 

55 

55 

Quality assessment 

5

suffering from severe handicaps. Calibration and weighting were applied to compensate for under-representation. 
It is useful to note that in France, EHIS was embedded in an existing national health survey (ESPS survey). In 
the United Kingdom, different sampling methodologies were applied in Great Britain and Northern Ireland. In 
Great Britain, EHIS wave 2 was conducted as a follow-up of the LFS survey, while in Northern Ireland, a simple 
random sample of households on the Land and Property Services Agency property gazetteer was used. Although 
the sample designs used for Great Britain and Northern Ireland were different, the outputs produced are 
considered comparable.  

From the point of view of national comparability of the results, all countries mentioned that it is assured at lower 
territorial levels. Some additional remarks were: the region of Ahvenanmaa in Finland had few observations to 
assure representativeness of the results, in France, EHIS wave 2 did not cover some overseas territories 
included in EHIS wave 1, while in the Netherlands, Caribbean Islands and the West Frisian Islands (with the 
exception of Texel) were excluded from the survey, as foreseen in the Commission implementing Regulation. 

5.4.4. Comparability over time 

An assessment of the comparability of the variables between the two waves is in the EHIS will be undertaken in a 
separate Eurostat study. At national level, just France mentioned that the survey design and data collection mode 
between EHIS wave 1 and 2 differed. Also, the Czech Republic stated that the sampling procedure was different 
between the two waves and that may have impact on the comparability of the results.  

5.5. Coherence 

Statistical outputs have the potential to be validly combined and used jointly. Statistics produced from the EHIS 
shall be comparable with those from EU-SILC for the three questions of the Minimum European Health Module 
(MEHM) or national health surveys (cross-domain coherence). An assessment of the coherence of the MEHM 
variables between in EHIS wave 2 and EU-SILC will be undertaken in a separate Eurostat study. Despite that, 
some countries specifically referred to that in their quality reports.  

Coherence with EU-LFS: Austria. 

Coherence with EU-SILC (MEHM questions): Bulgaria, the Czech Republic, Cyprus, Ireland, Greece, France and 
Austria coherence of the EHIS variables on “Self-perceived health” (HS1) and “General activity limitation” (HS3) 
with those derived from SILC. Similarly, the same holds in Romania (HS1) and in France (“long standing health 
problems” (HS2)).  

Coherence with other national surveys: Bulgaria, Spain, Poland, Finland. 

56 

Quality report of the second wave of the European Health Interview survey 

56 

Conclusions 6 

6 Conclusions 

Overview 

The European Quality Report on EHIS outlines different aspects of data quality, including quantitative quality 
information, with regard to the implementation of the 2nd wave of the EHIS. Underlying issues in:

a)

b)

c)

the methodology for the implementation of the survey at national level,

in the national adaptations of the EHIS model questionnaire,

as well as in the main characteristics and technical features of the surveys in the 28 EU member states
(MSs) complemented by Iceland and Norway,

provide important information for an accurate interpretation of the EHIS statistics. Moreover, they assist users of 
those statistics to evaluate the degree of comparability achieved.  

EHIS collects a multitude of variables on health status, health care and health determinants, which are 
complemented by demographic and socio-economic background variables. The survey is the main statistical tool 
providing harmonised statistics covering those health topics in the EU.  

Similar to other cross-national surveys, the national surveys implementing the 2nd wave of EHIS were not
conducted in exactly the same way. For example, there were differences in: 

a)

b)

c)

d)

the extent of the national questionnaires and their alignment with national needs,

the modes of data collection and administration used,

the proxy participation and

the data collection period.

Overall, the results of the quality assessment, meet expectations with regard to the quality of survey 
implementation and to its performance. The countries followed Eurostat’s guidelines and the Commission 
Regulation implementing EHIS wave 2 as much as they were able to. Important but inevitable factors that might 
have influenced the results are the different organizational structures of health care services on national or local 
level as well as adaptations in the questions’ wording to better reflect the specificities of national language(s). 

Survey methodology 

The Commission Regulation implementing EHIS calls for a selection of nationally representative probability 
samples. Eurostat, in close cooperation with the MS, proposed methodological and practical recommendations 
and guidelines on the sampling procedure and the implementation process of the survey. Countries, based on 
three main types of sampling frames, selected a nationally representative probability sample of the reference 
population, including individuals aged 15 and over living in private households and residing in the territory of the 
country at the time of data collection. In limited cases, where the target population was expanded to younger age 
groups, respondents were excluded when calculating the respective effective sample size.  

In all countries persons living in collective households and institutions were excluded from the target population. 

Quality report of the second wave of the European Health Interview survey 

57 

Conclusions 6 

In addition, the Commission Regulation defines the minimum effective sample sizes to be achieved, i.e. the 
actual sample sizes shall be larger to the extent that the design effect exceeds 1.0 and to compensate for all 
kinds of non-response. The ratio of the reached effective sample size to the minimum effective sample size – 
using the design effect with regard to the indicator “percentage of people severely limited in daily activities” – 
exceeded 1.0 in the majority of the countries for which information was available. While no issues can be raised 
for the sampling design and procedure, nevertheless it shall be taken into consideration that three countries 
implemented the survey as a follow-up of the LFS, which might have influenced the accuracy of the results due to 
potential introduction of selection bias. 

Survey implementation 

All countries made great efforts to ensure that the questionnaire meets its purpose and that questions are well 
communicated, to achieve a high response rate and to monitor the quality of the data collection. More than half of 
countries pre-tested the questionnaire, either through simply testing or cognitive interviews, sent advance 
notification letters, and made at least three attempts for contacting selected persons before receiving a refusal for 
participation. Moreover, they received feedback on the quality of the interview, like interviewer’s behavior and 
duration of interview, through contacts with a subset of randomly selected respondents.  

A first issue of consideration is the mode of data collection and administration used at national level, given the 
length of the questionnaire and the complexity of the concepts used. Most countries used face-to-face interviews 
either as the only mode of data collection or in combination with another mode (e.g. telephone interview or web 
questionnaires), followed by telephone interviews and postal or web surveys as the only mode of data collection. 

Overall, five countries used solely a self-administered mode. It should be noted here that a self-administered 
mode may offer many advantages but introduces the risk of measurement errors or selective bias. As a matter of 
fact, four of five countries that had used a self-administered mode, recorded relatively higher unit non-response 
rates. The self-administered mode also introduces in particular the issue of modifying the model questionnaire as 
well as adapting the instructions, examples and explanations of concepts for the different modes of data 
collection. So, for example, a couple of countries that had used solely a self-administered mode mentioned that 
the instructions and explanations were less elaborated compared to those included in the model questionnaire.  

Another issue for consideration comes from the fact that some countries integrated EHIS questions in their 
national HIS questionnaire and included additional questions. Longer questionnaires may have resulted to higher 
item non-response rates, due to respondent’s fatigue; or they might have an impact on the comparability of the 
resulted figures. It should be mentioned however, that according to Eurostat’s guidelines the addition of 
questions in specific submodules or the introduction of new submodules was allowed under the condition that 
those changes do not have an impact on the results of the compulsory variables. 

Following the discussion about the mode of data collection, it can be noted that the average duration of 
interviews varied across countries. This recorded variation is closely related to two factors: 
a) the mode of data collection and administration used per country and
b) the use of administrative data for the derivation of some core social variables.
Both factors may have contributed to the reduction of the average time of completion of the questionnaire. 
Keeping those factors in mind, we also underline that it was not always clear from the available information 
whether the reported average interview durations referred only to the HIS questions or to the whole national 
questionnaire.  

Moreover, seven countries offered incentives to the respondents to encourage them to participate in the survey. 
The use of incentives may be considered as another factor that could potentially have introduced selection bias, 
and thus influencing the accuracy of the results. 

Quality assessment 

With reference to the overall accuracy of the results, the vast majority of countries did not raise any significant 
issues. The quality of the sampling frame was high across all participating countries, since the time lag between 
their update and the time of actual sampling was, in most cases, narrow and the coverage was high.  

The standard errors for three key indicators based on the Minimum European Health Module (MEHM), completed 
by one health care indicator and one health determinants indicator, namely:  

-  HS1: proportion of respondents in good or very good health, 

Quality report of the second wave of the European Health Interview survey 

58 

Conclusions 6 

-  HS2: proportion of respondents with a longstanding illness, 

-  HS3: proportion of respondents severely limited in activities people usually do because of health 

problems for at least the past 6 months, 

-  HO1: proportion of respondents declaring having been hospitalized in the past 12 months, 

- 

BM1, BM2: proportion of respondents who are obese (BMI>=30), 

on average, did not exceed the value of 0.70. Thus, standard errors did not reveal any issues of low reliability. 

Proxy use in EHIS wave 2, i.e. participation in the survey via another person in the household, was allowed in 18 
out of 30 countries that participated in the survey. Four of those countries allowed the use of proxy interviews for 
the whole set of questions. Evidently, the usage of proxy interviews may have impact on the accuracy of the 
results, since such questions in particular are based on respondents’ self-perception and/or refer to the 
experiences of the respondents. The effect of proxy use on the accuracy of the results is an issue that requires 
further investigation. 

The overall unit non-response rate ranged in relatively low levels (less than 30 %) in 11 countries, while in five 
countries, the respective rate exceeded 50 %. As already mentioned, countries that used solely a self-
administered mode of data collection recorded high non-response rates but it should be also considered that in 
those cases proxy interviews were not used at all. Similarly, the unit non-response rate was high in most 
countries where proxy interviews were not allowed. Another factor influencing non-response stemmed from 
certain subgroups of the population that were more reluctant to participate in the survey. These groups were for 
example elderly or young persons, illiterate people, persons in urban areas, socially excluded or wealthy 
households. In general, countries were hardly able to assess the associated bias with non-response.  

With reference to item non-response, variables like physical activity/exercise, alcohol consumption or household 
income recorded more frequently high non-response rates. These were the same variables that were more 
frequently reported as problematic due to their very nature of asking sensitive information asked or of difficulties 
in understanding the concept of the question, of retrieving information for past experiences/events or of 
communicating or quantifying the requested information.  

Regarding comparability, countries implemented modifications in some questions. Some countries shortened 
clarifications or examples for the concepts used. Others grouped extensive answer categories or split or merged 
questions. Others again adapted questions to meet the specificities in their national language. Modifications were 
more frequently introduced to following submodules of: 

- 

- 

- 

- 

- 

PA: Preventive services,  

PL: Physical and sensory functional limitations, 

AC: Accidents and injuries, 

AM: Use of ambulatory and home care, 

SK: Smoking. 

Some of the modifications introduced may have influenced the comparability of the results either across countries 
or over time. But in general, an overall good comparability level across countries of the resulting data and 
indicators from EHIS wave 2 was achieved. 

Quality report of the second wave of the European Health Interview survey 

59 

Annex 

7 Annexes 

Annex 1: Sampling design 

Table 24. Sampling design, sampling unit and probability to draw the sample in EHIS wave 2 

Sampling 
design 

Stratified 
Multistage 
Cluster 
sampling 

Systematic 
Multistage 
Cluster 
sampling 

Stratified 
Multistage 
sampling 

Sampling unit 

Probability  used 
draw the sample 

to 

Number  of  selected 
individuals 

PSU: Municipalities in 
each region 
SSU: Households within 
each municipality 
TSU: Individuals in the 
selected household 

PSU: Census 
enumeration units 
SSU: Households within 
each census 
enumeration units 

Probability proportional 
to size (stepwise 
selection) 
Equal probability 
(stepwise selection) 
Unequal probability 

Maximum 4 members 
per household 

Probability proportional 
to size (cluster sampling) 
Unequal probability 
(systematic sampling) 

All household 
members aged 15 and 
over 

PSU: Census 
enumeration areas 
SSU: Dwellings 
TSU: Individuals 

Probability proportional 
to size 
Equal probability 
Equal probability 

A respondent per 
household successfully 
interviewed in LFS was 
asked to participate in 
EHIS 

Simple random 
sampling 

PSU: Individuals 

Equal probability 

PSU: Communities 
SSU: Individuals 

Probability proportional 
to size 
Equal probability per age 
group 

PSU: Individuals 

: 

- 

- 

- 

PSU: Block of 
households 
SSU: Households 
TSU: Individuals 

Probability proportional 
to size 
Equal probability 
Equal probability 

PSU: city blocks 
selected from each 
stratum 
SSU: Households within 
each city block 
TSU: Individuals from 

Probability proportional 
to size (stratified 
sampling) 
Equal probability 
Equal probability (simple 
random sampling) 

One household 
member aged 15 and 
over 

One household 
member 

Stratified 
Multistage 
sampling 

Systematic 
Stratified 
sampling 

Stratified 
Multistage 
Cluster 
sampling 

Stratified 
Multistage 
sampling 

BE 

BG 

CZ (1)

DK 

DE 

EE 

IE 

EL 

Quality report of the second wave of the European Health Interview survey 

60 

Annex 

Probability  used 
draw the sample 

to 

Number  of  selected 
individuals 

Probability proportional 
to size (stratified 
sampling) 
Equal probability 
Equal probability 

Unequal probability, 
proportional to the 
number of adults 
affiliated to one of the 
schemes of the National 
Health survey 

One household 
member 

All household 
members aged 15 and 
over of the selected 
beneficiary 

PSU: Census segments 
SSU: Dwellings 
selected from segments 

Probability proportional 
to size 
Equal probability 

- 

Probability proportional 
to size 
Equal probability 

All members of the 
household aged 15 
and over 

Equal probability 

All members of the 
household aged 15 
and over 

Sampling 
design 

Sampling unit 

each household 

Stratified 
Multistage 
cluster sampling 

PSU: Census Sections 
SSU: Dwellings 
TSU: Individuals 

Cluster 
sampling 

Stratified 
Multistage 
sampling 

Multistage 
sampling 

Stratified 
sampling 

Stratified 
Multistage 
sampling 
(CAPI), 
Stratified 
sampling (CATI) 

Senior beneficiaries of 
health insurance are 
selected as the 
reference unit 

PSU: Municipalities 
SSU: Households 

Households selected 
from the 9 geographical 
areas of the country 
(strata) 

CAPI: stratification by 
type of municipality (4 
strata): 
PSU: sampling areas 
SSU: individuals (6 in 
each sampling area) 
CATI: stratification by 
usage of public health 
services and age 
groups (strata). 
Selection of individuals 
in each stratum 

Probabilities proportional 
to size 
Equal probabilities for 
SSUs 

Equal probabilities for 
individuals in the stratum 

Simple random 
sampling 

Selection of individuals 

Equal probabilities 

Stratified 
sampling 

Multistage 
sampling 

Stratified 
sampling 

Multistage 
stratified 
sampling 

Stratified 
sampling 

Stratified 
Multistage 
Cluster 
sampling 

Selection of individuals 
within 36 strata (sex, 
age group, district) 

PSU: Settlements 
SSU: Individuals 

PSU: Individuals 

PSU: Municipalities 
selected in each region 
SSU: Individuals 
selected from each 
municipality 

Equal probabilities 

Probability proportional 
to size 
Unequal probability 

Probability proportional 
to size 

Probability proportional 
to size 
Equal probabilities 

Individuals within each 
geographic area 

Equal probability 
(systematic sampling) 

PSU: Census areas 
selected in each 
stratum 
SSU: Dwellings 

Probability proportional 
to size 
Equal probabilities 
Equal probabilities 

- 

- 

- 

- 

- 

: 

- 

All household 
members 

Systematic 

PSU: Census Sections 

Probability proportional 

One person per 

Quality report of the second wave of the European Health Interview survey 

61 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

Annex 

Number  of  selected 
individuals 
household 

All households in the 
dwelling and all 
members of the 
household 

- 

One member per 
household 

- 

- 

All members of 
selected households 
aged 16 and over were 
eligible to participate in 
EHIS. As a follow-up of 
the LFS, only those 
who had not objected 
to take part in future 
surveys were 
contacted. 

Sampling 
design 
Multistage 
Cluster 
sampling 

Multistage 
stratified 
sampling 

Multistage 
stratified 
sampling 

Multistage 
stratified 
sampling 

Simple random 
sampling 

Stratified 
sampling 

Sampling unit 

SSU: Dwellings 
selected from each PSU 
with systematic 
sampling 
TSU: Individual 

PSU: group of census 
sections 
SSU: dwellings in each 
PSU 

PSU: Regions 
SSU: Individuals 

PSU: census districts 
SSU: Dwellings random 
sampling 
TSU: Individuals 

to 

Probability  used 
draw the sample 
to size 
Equal probabilities 
(systematic sampling) 
Equal probabilities (last 
birthday method) 

Probability proportional 
to size 
Equal probability 

Probability proportional 
to size 
Equal probabilities 

Probability proportional 
to size 
Equal probabilities 
Equal probabilities 
(simple random 
sampling) 

PSU: Individuals 

Equal probabilities 

PSU: Individuals (strata: 
age, sex, country of 
birth) 

: 

RO 

SI 

SK 

FI 

SE 

UK 
(England 
and 
Scotland) 
(2)

Systematic 
random 
sampling (using 
the postcode 
address file 
(PAF)) 

UK 
(Northern 
Ireland) (2)

IS 

NO 

Simple random 
sampling (using 
the Land and 
Property 
Services 
Agency 
property 
gazetteer) 

Simple random 
sampling 

Stratified 
sampling 

PSU: Addresses 

Unequal probability 
across country to allow 
analysis at lower levels 

PSU: Households 

PSU: Individuals 

: 

: 

PSU: Individuals 

Equal probabilities 

: 

- 

- 

(1) The description refers to the selection of respondents for LFS (PSU and SSU) and followed-up by the selection of individuals for EHIS (TSU). 

(2) In Scotland and Wales a sample, stratified by country, was drawn from the final-wave LFS households. As a follow-up survey, only those aged 
16 or over who had not objected to take part in future surveys were selected for EHIS. The LFS sample is selected using systematic sampling 
from the postcode address file (PAF) ordered by postcode.  For Northern Ireland, a simple random sample of households from the Land and 
Property Services Agency gazetteer was selected. 

: Information not available; - Value/information not applicable. 

Quality report of the second wave of the European Health Interview survey 

62 

Annex 2: Mode of data collection and use of administrative data 

Table 25. Mode of data collection and use of administrative data in EHIS wave 2 

Annex 

Self-administered questionnaires 

Variables completed from other sources 

Data collection method & 
mode 

Method 

Mode 

Use of self-
administered 
mode 

Mode 

Face-to-face  PAPI - CAPI 

Face-to-face  PAPI 

Yes 

Yes 

Paper 

Paper 

Face-to-
face, 
Telephone 

PAPI - CAPI, 
Telephone 
(non-electronic 
version) 

Yes 

Paper 

Postal, Use 
of internet 

Postal, Use 
of internet 
Face-to-
face, Use of 
internet 

Postal, Use 
of internet 

PAPI, CAWI 

PAPI, CAWI 

Yes 

Yes 

Paper, Web 
questionnaire 

Paper, Web 
questionnaire 

All 

All 

CAPI, CAWI 

Yes 

Web questionnaire 

PAPI, CAWI 

Yes 

Paper 

Face-to-face  PAPI 

Face-to-face  CAPI 
Postal, 
Face-to-
face, 

PAPI, CAPI, 
CATI 

No 

No 

- 

- 

Yes 

Paper 

Sub-
modules/variable
s allowed 
HS, AL, MH, PE, 
SK, AL, SS 
SK, AL 

All (when the 
interviewer was 
giving the paper 
questionnaire in 
the household for 
self-completion) 

All (except certain 
blocks) 

HS, CD, AW, PL, 
PC, HA, PN, MH, 
HO, AM, MD, PA, 
UN, BM, PE, FV, 
SK, AL, SS, IC 
- 

- 
All except for UN, 
core variables 
(collected via 

Source 

Variables 

ADMIN 

(1) Date of birth, (2) Sex 

- 

LFS 

ADMIN 

- 
(1) Sex, (2) Country of residence, (3) Birthplace, (4) 
Country of citizenship, (5) Region of residence, (6) 
Degree of urbanisation, (7) Highest level of 
education completed, (8) Full or part-time work, (9) 
Self-declared labour status, (10) Occupation in 
employment, (11) Economic sector in employment, 
(12) Number of persons living in household, (13) 
Type of household, (14) Number of persons aged 
16 – 64 in the household who are employed 
(1) Country of birth, (2) Country of citizenship at 
time of data collection, (3) Region of residence, (4) 
Degree of urbanisation 

ADMIN 

(1) Region, (2) Degree of urbanisation 

ADMIN 

(1) Level of education 

LFS 

Demographic data 

- 

- 

- 

- 

ADMIN 

(1) Sex, (2) Age 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

Quality report of the second wave of the European Health Interview survey 

63 

Data collection method & 
mode 

Method 

Mode 

Telephone 

Face-to-
face, 
Telephone 

PAPI, 
Telephone 
(non-electronic 
version) 

Face-to-face  PAPI 

CAPI, CATI, 
CAWI 

Face-to-face  CAPI 
Face-to-
face, 
Telephone, 
Use of 
internet 
Face-to-face  PAPI - CAPI 
Postal, Use 
of internet 
Face-to-face  CAPI 

PAPI, CAWI 

Face-to-face  PAPI 

Self-administered questionnaires 

Variables completed from other sources 

Use of self-
administered 
mode 

Mode 

Sub-
modules/variable
s allowed 

CAPI - CATI) 

Source 

Variables 

Annex 

No 

- 

- 

Yes 

No 

Paper 

- 

SK, AL 

- 

- 

- 

- 

- 

- 

- 

Yes 

Web questionnaire 

All 

ADMIN 

(1) Sex, (2) Age, (3) Legal marital status, (4) 
Birthplace, (5) Country of citizenship 

Yes 

Yes 

No 

No 

PAPI, CAPI 
Paper, Web 
questionnaire 
- 

Paper 

SK, AL 

ADMIN 

(1) Region, (2) Sex, (3) Age 

SK, AL, HS 

- 
SK, AL, 
HHINCOME 

- 

- 

- 

- 

- 

- 

Face-to-
face, Use of 
internet 

Telephone, 
Postal (only 
for PE) 

CAPI, CAWI 

Yes 

Paper 

AL 

ADMIN 

CATI, PAPI 

Yes 

Paper 

PE 

LFS 

Face-to-face  PAPI 
Face-to-
face, Use of 

CAPI, CAWI 

No 

Yes 

- 

- 

Web questionnaire 

All 

- 

- 

(1) Birthplace, (2) Country of citizenship, (3) Region 
of residence, (4) Degree of urbanisation, (5) Legal 
marital status, (6) De facto Marital status, (7) 
Household income 
(1) Sex, (2) Country of residence, (3) Birthplace, (4) 
Country of citizenship, (5) Region of residence, (6) 
Degree of urbanisation, (7) Highest level of 
education completed, (8) Full or part-time work, (9) 
Self-declared labour status, (10) Occupation in 
employment, (11) Economic sector in employment, 
(12) Number of persons living in household, (13) 
Type of household, (14) Number of persons aged 
16- 64 in the household who are employed 
- 

- 

Quality report of the second wave of the European Health Interview survey 

64 

HR 

IT 

CY 

LV (1)

LT 

LU 

HU 

MT 

NL (2)

AT 

PL 

PT 

Data collection method & 
mode 

Method 

Mode 

internet 

Face-to-face  PAPI 
Face-to-
face, Use of 
internet 
Face-to-face  PAPI - CAPI 

CAPI, CAWI 

Postal 

PAPI 

Postal, 
Telephone, 
Use of 
internet 
Face-to-
face, 
Telephone 
Telephone 

PAPI, CATI, 
CAWI 

CAPI, CATI 

CATI 

Telephone 

CATI 

RO 

SI 

SK 

FI 

SE (3)

UK 

IS 

NO 

Self-administered questionnaires 

Variables completed from other sources 

Use of self-
administered 
mode 

Mode 

Sub-
modules/variable
s allowed 

Source 

Variables 

Annex 

Yes 

Yes 

Yes 

Yes 

Yes 

No 

No 

No 

Paper 

SK, AL 

- 

- 

Web questionnaire 

All 

ADMIN 

(1)  NUTS regions, (2) degree of urbanisation 

Paper 

Paper 

Paper, Web 
questionnaire 

- 

- 

- 

SK, AL 

All 

All 

- 

- 

- 

- 

ADMIN 

ADMIN 

- 
(1) Age, (2) Sex, (3) Marital status, (4) Living area, 
(5) Profession, (6) Income, (7) Education 
(1) Sex, (2) Birthplace, (3) Country of citizenship, (4) 
Country of residence, (5) Degree of urbanisation, 
(6) Highest level of education completed, (7) Full or 
part-time work, (8) Self-declared labour status 

ADMIN 

(1) Degree of urbanization, (2) Level of education 

ADMIN 

ADMIN 

(1) Degree of urbanization, (2) Household income 
(1) Country of birth, (2) Degree of urbanization, (3) 
Region, (4) Citizenship, (5) Income, (6) Level of 
educations 

(1) Use of a self-administered questionnaire for all persons excluding those aged between 15 and 17. Self-administered mode was not used in face-to-face interviews. 

(2) A letter was sent asking persons to complete the self-administered electronic questionnaire. If after two reminders no response was received, an attempt for a personal interview was made. 

(3) A group of the sampled persons was sent an invitation to participate to the online survey. A strategic sample of those who did not respond to the self-administered survey was further approached for a telephone interview. 

Note: ADMIN denotes administrative data. 

- Value/information not applicable. 

Quality report of the second wave of the European Health Interview survey 

65 

Annex 3: List of abbreviations and symbols 
Statistical symbols 

Annex 

: 

- 

% 

Not available 

Not applicable 

Per cent 

Acronyms and abbreviations 

EHIS 

ESS 

CAPI 

CATI 

CAWI 

LFS 

European Health Interview Survey 

European Statistical System 

Computer-assisted personal interviews 

Computer-assisted telephone interviews 

Computer-assisted web interviewing 

Labour Force Survey 

MEHM 

Minimum European Health Module 

MS 

PAPI 

SILC 

Member State 

Paper and pencil interviews 

Statistics on Income and Living Conditions 

Country abbreviations 

BE 

BG 

CZ 

DK 

DE 

EE 

IE 

EL 

ES 

FR 

HR 

IT 

CY 

LV 

LT 

Belgium 

Bulgaria 

Czech Republic 

Denmark 

Germany 

Estonia 

Ireland 

Greece 

Spain 

France 

Croatia 

Italy 

Cyprus 

Latvia 

Lithuania 

LU 

HU 

MT 

NL 

AT 

PL 

PT 

RO 

SI 

SK 

FI 

SE 

UK 

IS 

NO 

Luxembourg 

Hungary 

Malta 

Netherlands 

Austria 

Poland 

Portugal 

Romania 

Slovenia 

Slovakia 

Finland 

Sweden 

United Kingdom 

Iceland 

Norway 

Submodule codes 

HS 

CD 

AC 

AW 

Health status 

Chronic diseases 

MD  Medicine use 

PA  Preventive services 

Accidents and injuries 

UN  Unmet needs for health care 

Absence 
problems) 

from  work 

(due 

to  health 

BM  Weight and height 

PL 

Physical and sensory functional limitations  PE 

Physical activity/exercise 

Quality report of the second wave of the European Health Interview survey 

66 

PC 

HA 

PN 

MH 

HO 

Personal care activities 

Household activities 

FV  Consumption of fruit and vegetables 

SK  Smoking 

Pain 

Mental health 

Health care 

AL 

SS 

IC 

Alcohol consumption 

Social support 

Provision  of 
assistance 

informal 

care  or 

AM 

Use of ambulatory and home care 

Annex 

Quality report of the second wave of the European Health Interview survey 

67 

Getting in touch with the EU 

In person 
All over the European Union there are hundreds of Europe Direct Information Centres. You can 
find the address of the centre nearest you at: http://europa.eu/contact 

On the phone or by e-mail 
Europe Direct is a service that answers your questions about the European Union. You can 
contact this service  
– by freephone: 00 800 6 7 8 9 10 11 (certain operators may charge for these calls),
– at the following standard number: +32 22999696 or
– by electronic mail via: http://europa.eu/contact

Finding information about the EU 

Online 
Information about the European Union in all the official languages of the EU is available on the 
Europa website at: http://europa.eu   

EU publications 
You can download or order free and priced EU publications from EU Bookshop at: 
http://bookshop.europa.eu. Multiple copies of free publications may be obtained by contacting 
Europe Direct or your local information centre (see http://europa.eu/contact) 

EU law and related documents 
For access to legal information from the EU, including all EU law since 1951 in all the official 
language versions, go to EUR-Lex at: http://eur-lex.europa.eu 

Open data from the EU 
The EU Open Data Portal (http://data.europa.eu/euodp/en/data) provides access to datasets from 
the EU. Data can be downloaded and reused for free, both for commercial and non-commercial 
purposes. 

Quality report of the 
second wave of the 
European Health  
Interview survey

The purpose of this quality report is to provide the users of the European 
Union Health Statistics with a tool for assessing the quality of these 
statistics which are based on the European Union Health Interview 
Survey (EHIS). The report provides a description of the methodology of 
the second wave of EHIS and an overview of the survey implementation 
by ESS countries between 2013 and 2015. This is followed by a 
presentation and discussion of the main quality indicators for EHIS wave 
2 which, in this report, are: instruments and characteristics of quality 
management, accuracy and reliability of the survey sampling, timeliness 
and punctuality of the survey implementation and dissemination, and 
comparability and coherence of the survey results. The lessons learned 
can be used for the next round of EHIS wave 3 that will take place in ESS 
countries between 2018 and 2020. 

For more information
http://ec.europa.eu/eurostat/

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ISBN 978-92-79-82069-4

Quality report of the second wave of the European Health Interview survey2018 edition