National Center for Health Statistics

An Introduction to the Washington Group Short Set on Functioning

FCSM Research & Policy Conference

October 25, 2023

Cordell Golden

Division of Analysis and Epidemiology
Overview

• The UN International Seminar on the Measurement of Disability

• The Washington Group on Disability Statistics

• The WG Short Set on Functioning

• The ACS disability question set

2
UN International Seminar

on the Measurement of Disability

In June 2001, the UN convened a seminar to review and assess the current status of methods 

used in population-based data collection activities to measure disability in national statistical 

systems.

• Bring together a broad array of developed and developing country experts in disability 

measurement for statistical reporting;

• Develop recommendations and priorities to advance the work on measurement of 

disability;

• Contribute to building a network of institutions and experts, including producers and users 

of disability statistics to implement developments in this field;

• The work to achieve these objectives should build on accepted international standards and 

guidelines.

3
The Washington Group

on Disability Statistics (WG)

In February 2002, the WG held its first meeting

• To guide the development of a small set(s) of general disability measures, suitable for 

use in censuses, to provide basic necessary information on disability throughout the 

world.

• To recommend one or more extended sets of survey items to measure disability to be 

used as components of population surveys or as supplements to specialty surveys. 

These extended sets of survey items will be related to the general measures.

• To address the methodological issues associated with the measurement of disability 

considered most pressing by the City Group participants.

4
The WG is Country-Driven

• Countries have ownership:

• Representatives include the National Statistical Offices of 168 countries and 

territories, international organizations, and organizations that represent 

persons with disabilities

• The Secretariat for the WG is located at NCHS (US).

• The chosen Chairperson for the WG also at NCHS (US).

• A Steering Committee oversees the WG work plan.

• Work Groups carry out the work plan, input from all members.

• Emphasis on evidence and transparency, with extensive testing of data collection 

tools in multiple countries.

5
Developing the WG Tools:

The WG-SS
Disability Data Needs

National data on the population with disabilities are needed by countries:

• To support the development and evaluation of policies and programs 

to enhance social participation

• To both implement and monitor the UN Convention on the Rights of 

Persons with Disabilities

• For disaggregation in monitoring progress towards the 2030 Agenda for 

Sustainable Development Goals

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WG Short Set Objectives

• Identify persons with similar types and degree of functional limitations in basic actions 

regardless of nationality or culture;

• Represent the majority (but not all) persons with limitations in basic actions; and

• Represent commonly occurring limitations in functioning domains that can be 

captured in the census context.

The WG defined an approach to measuring disability based on identifying those who:

• because of difficulties doing certain universal, basic actions, 

• are at greater risk than the general population

• for limitations in participation.

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WG Purpose for Measurement:

Equalization of Opportunities

• Seeks to identify all those at 

greater risk than the general 

population for limitations in 

participation

• Disability used as a demographic 

for disaggregation

0

30

60

90

Proportion (%)

Without

disability

With

disability

Employed (%)

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WG Short Set on Functioning (WG-SS)

1. Do you have difficulty seeing even if wearing glasses?

2. Do you have difficulty hearing even if using a hearing aid?

3. Do you have difficulty walking or climbing steps?

4. Do you have difficulty remembering or concentrating?

5. Do you have difficulty with self-care, such as washing all over or dressing?

6. Using your usual language, do you have difficulty communicating (for example 

understanding or being understood by others)?

Response categories:

No difficulty / Some difficulty / A lot of difficulty / Cannot do at all

10
Disability Prevalence, U.S. 2021

Cutoff Person with disability has n

%

(weighted)

1 at least 1 domain is ‘some difficulty’ 13,705 43.4

2 at least 2 domains are ‘some difficulty’ 6,775 20.4

3 at least 1 domain is ‘a lot of difficulty’ 3,008 8.8

4 at least 1 domain is ‘unable to do it’ 459 1.3

Source: National Health Interview Survey, 2021, adults age 18+

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Advantages

• Functional approach consistent with WHO International Classification of 

Functioning, Disability and Health (ICF) Model

• Identifies most people with disabilities

• Captures severity and domain-specific functioning

• Tested successfully in many countries (low, middle, and high income)

• Designed to be internationally comparable

• Can easily be added to existing censuses and surveys or to project-based 

data collections:

- Approximately 1.25 minutes to administer

- Wealth of implementation and analysis guidance

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Where in the World is the WG-SS?

Source: Based on 2009-2023 reported use of the WG-SS in annual submission of WG Country Report forms (n=123) 13
WG-SS Questions Adopted Widely

• Endorsed as the means for collecting disability data in the 2020 round of censuses – the UN 

Statistical Division and the UN Economic Commission for Europe.

• Used in censuses or surveys in over 123 countries to date. 

• Promoted as the means to collect disability data in all programs and projects by international 

development and aid programs – USAID, FCDO (UK), DFAT (Australia), NORAD (Norway), MFA 

(Finland), GIZ (Germany).

• Adopted in all sponsored household surveys including the World Bank Living Standards 

Measurement Study (LSMS) and USAID Demographic and Health Surveys (DHS)

• Adopted as the way to disaggregate data across a variety of global and regional initiatives, including 

the Incheon Strategy on Making the Right Real in Asia.

• Recommended as the means for disaggregating the SDGs by disability – UN DESA’s Disability Data 

Experts Group – and data collected in humanitarian and crises contexts.

• OPDs, NGOs, INGOs, UN agencies.

• Included in U.S. collections, including NHIS, NHANES, NSFG, Pulse, and more to come... 

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Improving U.S. Census Disability Data:

The ACS Set
Selected Historical Moments and Disability 

Measurement Changes

1990: 

ADA

2001:

UN International Seminar 

on Disability 

Measurement

WHO ICF Model

2009: 

ACS Set in 

NHIS

2010: 

PPACA

WG-SS

in NHIS

2013:

ACS Set in 

BRFSS

2008:

ACS Set 

in ACS 

and CPS

2021:

WG-SS

in NSFG

2006:

Formal adoption of WG-SS

OMB Interagency Committee for the 

ACS calls for assessment of ACS 

disability content

Jan-March: NCHS leads interagency 

Subcommittee on Disability 

Measurement and Content Test for 

new items

2002: 

First WG meeting 

in DC

Focus on short set 

of questions, 

consistent with 

ICF, for censuses 

and surveys

2006:

UNCRPD Adopted 

with highest number 

of signatories in 

history to a UN 

Convention on its 

opening day

(30 March 2007)

2004-current: WG-SS cognitive/field testing worldwide

2006: ACS Content Test - cognitive/field testing by NCHS and Census

2020-2022: WG-SS 

cognitive/field testing 

by NCHS and Census

16

2019: 

WG Child 

Functioning 

Module added 

to NHIS

WG-SS

in NHANES
Census Disability Data Collections

2000 Census

1999-2007 ACS

2020 Census

2008-current ACS

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ACS Design Requirements for

Disability Questions

Work was subject to several strict guidelines and requirements. 

In particular, the revised questions:

• 6 questions which could not exceed the space limitations in the American 

Community Survey – constrained response set;

• must perform equally well across administration modes (mail, telephone, in- person);

• must be appropriate for the greatest proportion of individuals as possible, 

including young children;

• provide a valid, reliable and understandable general measure of disability; and

• would be fielded, without changes, for a 5-year period beginning with 2008 in 

order to generate 2010 Census estimates comparable in quality to the 2000 

Census long form estimates.

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Measurement Objectives

• Based on the legislative review (18 agencies had legislative mandates and the 

conceptual framework):

• “equalization of opportunity” was selected as the key policy question in 

areas such as housing, employment, communications, income and other 

areas of participation in society.

• Thus, the question set must identify persons who, because of their limitations 

in functioning, are at risk for discrimination or lack appropriate opportunity for 

participation.

• In addition, in order to meet legislative and programmatic requirements for 

services and other forms of support, a measure of severe disability identifying 

those in need of assistance to maintain independence should be included.

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For more information about the ACS set:

Disability in the ACS

2007 Evaluation Report Covering Disability

Review of Changes in Disability Measurement in the 2008 ACS

For more information about the WG:

WG Website Homepage

The WG Primer 

Disability Measurement & Monitoring Using the WG Questions

Resources

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For more information, contact CDC

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.