Effects of Form Length and

Item Format on Response

Patterns and Estimates of

Physician Office and Hospital

Outpatient DepartmentVisits

National Ambulatory Medical Care Survey and

National Hospital Ambulatory Medical Care

Survey, 2001

Series 2, Number 139 June 2005
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appreciated.

Suggested citation

Hing E, Schappert SM, Burt CW, Shimizu IM. Effects of form length and item

format on response patterns and estimates of physician office and hospital

outpatient department visits. National Center for Health Statistics. Vital Health

Stat 2(139). 2005.

Library of Congress Cataloging-in-Publication Data

Effects of form length and item format on response patterns and estimates of

physician office and hospital outpatient department visits: National Ambulatory

Medical Care Survey and National Hospital Ambulatory Medical Care Survey,

2001.

p. ; cm. -- (Vital and health statistics. Series 2, Data evaluation and

methods research ; no. 139) (DHHS publication; no. (PHS) 2005–1339)

‘‘April 2005.’’

Includes bibliographical references.

ISBN 0–8406–0600–1 1. Health surveys. I. National Ambulatory Medical

Care Survey (U.S.) II. National Hospital Ambulatory Medical Care Survey (U.S.)

III. National Health Care Survey (U.S.) IV. National Center for Health Statistics

(U.S.) V. Series: Vital and health statistics. Series 2, Data evaluation and

methods research ; no. 139. VI. Series: DHHS publication ; no. (PHS)

2005–1339.

[DNLM: 1. Health Care Surveys--instrumentation--United States. 2.

Ambulatory Care--statistics & numerical data--United States. 3. Emergency

Service, Hospital--statistics & numerical data--United States. 4. Evaluation

Studies--United States. 5. Questionnaires--United States. 6. Research

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W2 A N148vb no.139 2005]

RA409.U5 no. 139

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Series 2, Number 139

Effects of Form Length and

Item Format on Response

Patterns and Estimates of

Physician Office and Hospital

Outpatient DepartmentVisits

National Ambulatory Medical Care Survey and

National Hospital Ambulatory Medical Care

Survey, 2001

Data Evaluation and Methods Research

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Hyattsville, Maryland

June 2005

DHHS Publication No. (PHS) 2005-1339
National Center for Health Statistics

Edward J. Sondik, Ph.D., Director

Jack R. Anderson, Deputy Director

Jennifer H. Madans, Ph.D., Associate Director for Science

Lawrence H. Cox, Ph.D., Associate Director for Research

and Methodology

Edward L. Hunter, Associate Director for Planning, Budget,

and Legislation

Michael H. Sadagursky, Associate Director for

Management and Operations

Margot A. Palmer, Director for Information Technology

Phillip R. Beattie, Director for Information Services

Diane M. Makuc, Dr.P.H., Acting Associate Director for

Analysis and Epidemiology

Charles J. Rothwell, Director for Vital Statistics

Jane E. Sisk, Ph.D., Director for Health Care Statistics

Jane F. Gentleman, Ph.D., Director for Health Interview

Statistics

Clifford L. Johnson, Director for Health and Nutrition

Examination Surveys

Office of Research and Methodogy

Lawrence H. Cox, Ph.D., Associate Director

Kenneth M. Harris, Acting Chief, Interdisciplinary Research

Center and Laboratories

P. Douglas Williams, Acting Chief, Statistical Research and

Survey Design Staff
Contents

Abstract ................................................................................................. 1

Introduction ............................................................................................. 1

Research Objectives ..................................................................................... 2

Previous Research ...................................................................................... 2

Background .............................................................................................. 2

National Ambulatory Medical Care Survey .................................................................. 2

National Hospital Ambulatory Medical Care Survey ........................................................... 3

Methods ................................................................................................ 4

Split-panel Questionnaire Design .......................................................................... 4

Split-panel Sample Design ................................................................................ 4

Data Collection ......................................................................................... 4

Weighting and Estimation ................................................................................ 5

Analysis .............................................................................................. 5

Results ................................................................................................. 6

Effect on Provider Response .............................................................................. 6

Effect on Item Nonresponse .............................................................................. 6

Effect on Visit Estimates ................................................................................. 7

Feasibility of Collecting Data Items Specific to the Long Form .................................................. 10

Conclusions .............................................................................................. 11

References .............................................................................................. 13

Appendixes

I. Patient Record Forms................................................................................ 26

II. Definitions of Terms ................................................................................ 32

Text Figures

1. Unweighted physician response rate: National Ambulatory Medical Care Survey, 1989–2002 ..................... 2

2. Unweighted overall outpatient department response rate: National Hospital Ambulatory Medical Care Survey,

1997–2002 ........................................................................................ 4

3. Ratio of long form to short form estimate for selected diagnostic and screening services by survey: Split-panel

study, 2001 ........................................................................................ 9

4. Percent of visits with any culture ordered or collected by form length and survey: Split-panel study, 2001 .......... 9

5. Percent of office visits by respondent type and form length: Split-panel study, 2001 ............................ 10

6. Percent of visits to hospital outpatient departments by respondent type and form length: Split-panel study, 2001 ..... 10

7. Percent of office visits reporting one or more diagnostic or screening services and one or more counseling, education,

or therapeutic services by type of respondent: Split-panel study, 2001 ......................................... 11

8. Weighted item nonresponse rates for data items collected only on long form by survey: Split-panel study, 2001 ...... 12

iii
Appendix Figures

I. 2001 National Ambulatory Medical Care Survey Patient Record Form A (short form) ........................... 26

II. 2001 National Ambulatory Medical Care Survey Patient Record Form B (long form) ........................... 27

III. 2001 National Hospital Ambulatory Medical Care Survey Outpatient Department Patient Record

Form A (short form) ................................................................................ 29

IV. 2001 National Hospital Ambulatory Medical Care Survey Outpatient Department Patient Record

Form B (long form) ................................................................................ 30

Text Tables

A. Percent of visits to ambulatory care settings with standard errors, by number of diagnostic and screening services

ordered or provided and form length: Split-panel study, 2001 ............................................... 8

B. Percent of visits to ambulatory care settings with standard errors, by number of counseling, education, or therapeutic

services ordered or provided and form length: Split-panel study, 2001 ........................................ 8

Detailed Tables

1. Sample size and weighted physician response rate by form length and selected physician characteristics, with

standard error of rate, unadjusted odds ratio, and 95% confidence interval of odds ratio: Split-panel study, 2001 ...... 14

2. Sample size and weighted hospital outpatient department response rate by form length and selected hospital

characteristics, with standard error of rate, unadjusted odds ratio, and 95% confidence interval of odds ratio:

Split-panel study, 2001 .............................................................................. 15

3. Sample size and weighted hospital outpatient department clinic response rate by form length and selected hospital

and clinic characteristics, with standard error of rate, unadjusted odds ratio, and 95% confidence interval of

odds ratio: Split-panel study, 2001 ..................................................................... 16

4. Weighted overall hospital outpatient department response rate with standard error of rate, by form length and

selected hospital characteristics: Split-panel study, 2001 ................................................... 17

5. Weighted item nonresponse rates and standard errors of rates by form length and survey: Split-panel study, 2001 .... 18

6. Percent of visits to ambulatory care settings with standard error of percent by form length, ratio of estimates, and

selected diagnostic and screening services: Split-panel study, 2001 ........................................... 19

7. Percent of visits to ambulatory care settings with standard error of percent by form length, ratio of estimates,

selected diagnostic and screening services, and selected surgical procedures collected by short form write-in responses

and long form check boxes: Split-panel study, 2001 ....................................................... 20

8. Percent of visits to ambulatory care settings with standard error of percent by form length, ratio of estimates, and

counseling, education, or therapeutic services: Split-panel study, 2001 ........................................ 21

9. Percent of visits to ambulatory care settings with standard error of percent by form length, ratio of estimates, and

disposition: Split-panel study, 2001 .................................................................... 22

10. Percent of visits to ambulatory care settings with standard error of percent by form length, ratio of estimates, and

providers seen: Split-panel study, 2001 ................................................................. 23

11. Percent distribution of visits to ambulatory care settings and average number of medications with standard error of

percent by form length, ratio of estimates, medication therapy, and number of medications: Split-panel study, 2001 . . . 24

12. Percent of visits to ambulatory care settings with standard error of percent by selected characteristics asked only on

the long form: Split-panel study, 2001 .................................................................. 25

iv
Objectives

This report describes effects due to

form length and/or item formats on

respondent cooperation and survey

estimates.

Methods

Two formats were used for the Patient

Record form for the 2001 NAMCS and

OPD component of the NHAMCS: a

short form with 70 subitems and a long

form with 140 subitems. The short form

also contained many write-in items and fit

on a one-sided page. The long form

contained more check boxes and other

unique items and required a two-sided

page. The NAMCS sample of physicians

and NHAMCS sample of hospitals were

randomly divided into two half samples

and randomly assigned to either the short

or long form. Unit and item nonresponse

rates, as well as survey estimates from

the two forms, were compared using

SUDAAN software, which takes into

account the complex sample design of

the surveys.

Results

Physician unit response was lower

for the long form overall and in certain

geographic regions. Overall OPD unit

response was not affected by form

length, although there were some

differences in favor of the long form for

some types of hospitals. Despite having

twice the number of check boxes on the

long form as the short form, there was

no difference in the percentage of visits

with any diagnostic or screening

services ordered or provided. However,

visit estimates were usually higher for

services collected with long form

check-boxes than with (recoded) short

form write-in entries. Finally, the study

confirmed the feasibility of collecting

certain items found only on the long form.

Conclusion

Overall, physician cooperation was

more sensitive to form length than was

OPD cooperation. The quality of the

data was not affected by form length.

Visit estimates were influenced by both

content and item format.

Keywords: questionnaire design c

split-panel study c physician office

care c hospital outpatient care

Effects of Form Length and

Item Format on Response

Patterns and Estimates of

Physician Office and Hospital

Outpatient Department Visits

National Ambulatory Medical Care Survey and

National Hospital Ambulatory Medical Care

Survey, 2001

By Esther Hing, M.P.H.; Susan M. Schappert, M.A.; Catharine W.

Burt, Ed.D., Division of Health Care Statistics, and Iris M. Shimizu,

Ph.D., Office of Research and Methodology

Introduction

The National Ambulatory Medical

Care Survey (NAMCS) and

National Hospital Ambulatory

Medical Care Survey (NHAMCS)

provide nationally representative

estimates of the number and kinds of

medical encounters in physician offices,

hospital emergency departments (EDs),

and outpatient departments (OPDs). In

each survey, information on randomly

sampled encounters with eligible

providers is collected on the Patient

Record form (PRF). The information

collected is based on physician’s

knowledge of the patient and/or

abstracted from medical records. The

PRF collects information on

characteristics of the patient who made

the visit, such as age, sex, race,

ethnicity, and expected source of

payment; and visit characteristics such

as reason for visit, physician diagnoses,

tests and procedures ordered or

provided, medications provided or

prescribed, and disposition of visit.

Because the OPD component of the

NHAMCS was designed to produce

statistics on medical encounters similar

to those collected in the NAMCS, the

PRFs used in these two settings are

similar.

Both the NAMCS and NHAMCS

survey content and methodology are

often copied by other organizations and

governments to collect visit data, and

NAMCS and NHAMCS public use files

are popular sources for secondary

analysis. To maintain the quality of

estimates derived from these surveys,

efforts are needed to minimize

measurement errors due to nonresponse

and reporting errors. To refine the

survey instrument and collect data

needed by policymakers and the health

services research community, the PRF is

redesigned every few years. In planning

for the 2001 surveys, the PRF was

redesigned into a two-sided page that

included data items typically fielded,

many new data items requested by

consultants and an Expert Panel, as well

as many check boxes for the most

frequently written-in services. The

longer form was then tested in a pilot

study with a convenience sample of

physicians and hospitals. During the

pilot study with a convenience sample

of providers, the form required an

average of 13 minutes to complete

compared with an estimated 4 minutes

in recently fielded survey panels (1).

Page 1
Page 2 [ Series 2, No. 139

Additionally, comments from the

respondent and interviewer debriefing

indicated a negative reaction to the

longer form. However, it was thought

that the pilot test was too limited in

scope and may not have been

sufficiently robust to provide definitive

results pertaining to the feasibility of

collecting data items from a longer PRF.

To test instrumentation effects in a

real-life survey situation while

addressing concerns that a lengthy form

might negatively affect response rates,

the 2001 NAMCS and OPD component

of the 2001 NHAMCS were fielded as

split-panel surveys to compare two

versions of the PRF. Physicians sampled

for the NAMCS were divided into two

panels; one panel received a short

version of the PRF (Form A) and the

other received a longer version (Form

B) (see figures I and II). Similarly,

hospitals were divided into two panels;

eligible OPD clinics in each panel

received either the short or long form

(see figures III and IV).

Research Objectives

The goal of the split-panel study

was to measure PRF instrumentation

effects on

physician and hospital cooperation and

survey estimates in a real-world setting.

Another goal was to test the feasibility

of capturing more detailed survey

content. The purpose of this report is to

describe the conduct of the study and to

evaluate the effects of the split-panel

design on the quality and magnitude of

NAMCS and NHAMCS-OPD estimates.

Key questions addressed in this report are:

+ Did the length of the form affect the

willingness of physicians and OPD

clinics to participate?

+ How complete were the data

provided on each form?

+ Did the additional check boxes

provided on the long form result in

increased reporting of the listed

services compared with

corresponding data from the short

form items?

+ Was the short form’s write-in

response format an efficient way to

collect information on services

+ What was learned about data items

collected exclusively on the long

form?

Previous Research

Split-panel studies are typically

used to investigate interviewer effects

on responses, respondent

recall, errors due to questionnaire

wording or format, or mode effect (2).

There is little research on measurement

errors due to question wording or form

length for records-based surveys, such

as the NAMCS and NHAMCS. A

separate report describes the logistical

considerations of conducting a

split-panel test of forms while

simultaneously fielding a national

survey of physician visits (3).

Background

National Ambulatory

Medical Care Survey

The National Ambulatory Medical

Care Survey (NAMCS) has provided

nationally representative estimates of the

number and kinds of medical encounters

in physician offices since 1973. The

scope of the NAMCS is physician/

patient encounters in the offices of

nonfederally employed physicians

classified by the American Medical

Association (AMA) or American

Osteopathic Association (AOA) as

‘‘office-based, patient care.’’

Physicians in the specialties of

anesthesiology, radiology, and

pathology were excluded. Physicians

in private, nonhospital-based clinics

were included, but those in hospitalbased outpatient clinics were not.

Telephone contacts and nonoffice

visits were also excluded, as were

purely administrative visits (e.g., bill

payment, leaving specimens).

The NAMCS utilizes a multistage

probability sample design involving

samples of geographic primary sampling

units (PSUs), physician practices within

PSUs, and patient visits within

physician practices. The PSUs are

counties, groups of counties, county

equivalents (such as parishes or

independent cities), or towns and

townships for some PSUs in New

England, or a metropolitan statistical

area (MSA).

The U.S. Census Bureau was

responsible for data collection for the

2001 NAMCS. The Census Bureau

trained field representatives (FRs) who,

in turn, coordinated data collection from

physicians. FRs contacted physicians for

induction interviews after advance

letters were mailed by NCHS notifying

the physicians of their selection. During

the induction interview, the visit

ordered or provided at the visit? Figure 1. Unweighted physician response rate: National Ambulatory Medical Care Survey

1989–2002
Series 2, No. 139 [ Page 3

sampling rate is established, and the

final disposition of the interview is

recorded. The induction interview is also

used to obtain basic information about

the practice such as the physician’s

employment status, ownership of the

practice, practice size, and office type.

Sample physicians are asked to

complete PRFs for a systematic random

sample of visits occurring during a

randomly assigned 1-week period. In

2001, 1,252 of 1,910 in-scope

physicians participated in the NAMCS

by completing 24,281 PRFs. A total of

1,230 responded fully for an unweighted

response rate of 64.4 percent. Figure 1

presents the NAMCS response rates

during 1989–2002.

Statistics from the NAMCS are

derived by a multistage estimation

procedure that produces essentially

unbiased national estimates. The

estimation procedure includes inflation

by reciprocals of the sampling

selection probabilities, adjustment for

nonresponse, a population-weighting

ratio adjustment, and weight

smoothing.

It should be noted that the 24,281

PRFs completed across both panels of

the 2001 NAMCS include forms

completed by physicians with minimal

response (i.e., provided PRFs for less

than 50 percent of expected number of

sampled visits). PRFs from these

‘‘less-than-fully cooperating’’ physicians

were included on the data file, and the

weight of these visits and the visits from

similar physicians were increased to

account for the missing visit PRFs.

Physicians supplying a minimal

response are not considered respondents

for response rate calculations.

National Hospital

Ambulatory Medical Care

Survey

The National Hospital Ambulatory

Medical Care Survey (NHAMCS) is a

nationally representative survey of

ambulatory visits to hospital emergency

departments (EDs) and outpatient

departments (OPDs) conducted annually

since 1992. The scope of the NHAMCS

is patient visits to EDs and OPDs of

non-Federal, short-stay hospitals

(hospitals with an average length of stay

of less than 30 days) or those whose

specialty is general (medical or surgical)

or children’s general. Federal hospitals,

hospital units of institutions, and

hospitals with less than six beds are

ineligible for the NHAMCS. Telephone

contacts are excluded, as are purely

administrative visits. In OPDs, only

clinics supervised by a physician and for

which the hospital kept patient volume

statistics are included; ancillary clinics

(e.g., radiology, laboratory services,

physical rehabilitation, renal dialysis, and

pharmacy) are excluded. The hospital

sampling frame consisted of hospitals

listed in the 1991 SMG Hospital

Database, which was updated using the

2000 SMG Hospital Database to include

hospitals that opened or became eligible

after 1991. Approximately 50 newly

eligible hospitals were added to the 2001

sample. Hospitals that had lost eligibility

were dropped from both the sample and

sampling frame during the update.

A four-stage probability sample

design is used in the NHAMCS. The

design involves samples of geographic

PSUs, hospitals with EDs and/or OPDs

within PSUs, emergency service areas

(ESAs) within EDs, or clinic sampling

units (SUs) within OPDs, and patient

visits within ESAs or SUs. If a hospital

has five or fewer OPD clinics, all are

included in the survey. A clinic sampling

unit is generally one clinic, except when

a clinic expects fewer than 30 visits. In

that case, it is grouped with one or more

other clinics to form a clinic SU. If the

grouped SU was selected, all clinics

included in that SU were included in the

sample. In hospitals with more than five

OPD clinics, each clinic is assigned to

one of six specialty groups (i.e., general

medicine, surgery, pediatrics,

obstetrics/gynecology, substance abuse,

and other). Within each specialty group,

clinics are grouped into SUs, and a

sample of SUs is selected by using

probability proportional to the total

expected number of visits to the SU. A

maximum of 12 clinic SUs could be

selected because the sample of clinic

SUs within each specialty group is

limited to two. A sample of 479

hospitals was selected for the 2001

NHAMCS, of which 261 had eligible

OPDs.

The U.S. Census Bureau was

responsible for data collection for the

2001 NHAMCS. The Census Bureau

trained field representatives (FRs) who,

in turn, coordinated data collection from

hospitals. FRs contact hospitals for

induction interviews after advance

letters are mailed by NCHS notifying

the hospital of their selection. During

the induction interview, the visit

sampling rates are established and the

final disposition of the interview is

recorded. The induction interview is also

used to obtain basic information to

establish whether the hospital is in

scope for the survey, whether hospitals

have eligible EDs and/or OPDs, and to

determine eligibility of emergency

service areas and sampling units. Basic

information about the hospital,

emergency department, and outpatient

department are also collected in the

induction interview. This includes types

of clinics within an ED or OPD, visit

volume expected for each clinic,

hospital ownership, and bed size.

Hospital staff was asked to complete

Patient Record forms for a systematic

random sample of patient visits

occurring during a randomly assigned

4-week period. In 2001, 1,036 clinics

within 261 eligible OPDs participated

by completing 33,567 Patient Record

forms. The unweighted visit response

rate for OPDs in 2001 was 73.6 percent.

Figure 2 presents NHAMCS response

rates for OPDs during 1997–2002.

Similar to the NAMCS, statistics

from the NHAMCS are derived by a

multistage estimation procedure that

produces essentially unbiased national

estimates. The estimation procedure

includes inflation by reciprocals of the

sampling selection probabilities,

adjustment for nonresponse, and a

population-weighting ratio adjustment.

Similar to the NAMCS, the 33,567

Patient Record forms completed in

OPDs include those completed by

clinics with minimal response (provided

PRFs for less than 50 percent of

expected number of sampled visits). The

weights for PRFs from these and similar

clinics were increased to account for the

missing PRFs. Minimally responding

clinics are not considered respondents

for response rate calculations.
Page 4 [ Series 2, No. 139

Figure 2. Unweighted overall outpatient department response rate: National Hospital

Ambulatory Medical Care Survey, 1997–2002

Methods

Split-panel Questionnaire

Design

Two forms, one short and one long,

were tested in the 2001 split-panel

study. Both forms required an 8 × 14

inch sheet. However, the short form

took up only the front of the sheet, and

the long form covered both sides. Both

forms contained the same 12 broad

categories of items from past surveys,

but the long form included more new

items. There were more check box

options on the long than short form for

the following data categories: diagnostic

or screening services (44 on the long form

versus 18 on the short form); counseling,

education, or therapeutic services (23

versus 11); surgical procedures (4 versus

none); visit disposition (10 versus 7); and

providers seen (12 versus 8). The

medication question was the only data

item that permitted more write-in entries

on the long than the short form (8

medications versus 6).

With one exception, the short form

check boxes were a subset of check boxes

included on the long form. The exception

was the diagnostic or screening services

item, which included two check boxes

(general medical exam and other exam)

on the short form, but not on the long

form. The short form diagnostic or

screening services item also included four

boxes to allow write-in entries in place of

many check box items included on the

long form item. The latter feature was

included to study reporting differences

using write-in responses versus check

boxes, as well as to maximize the amount

of comparable data that could be

published in reports (4,5).

Split-panel Sample Design

The split-panel study was conducted

using the production samples of the

2001 NAMCS and 2001 NHAMCS

outpatient department component. That

is, after sample selection, NAMCS

physicians and NHAMCS hospitals were

randomly assigned to one of two panels.

One panel was assigned the short form

for data collection, and the other panel

used the long form. Randomized

assignment of questionnaires to replicate

samples enables attribution of differences

to the question or questionnaire.

Conducting the split-panel study using the

production samples of the NAMCS/

NHAMCS also ensured the same time

frame for the questionnaire items tested.

In the NAMCS, 3,000 physicians

were selected for the sample. Prior to

randomization, physicians within the

same group practice were identified to

ensure that the same form would be

administered to any multiple physicians

selected within the same medical practice.

As a result, the number of physicians on

each panel varied slightly: 1,496

physicians were assigned the short form

(Form A), and 1,504 physicians were

assigned the long form (Form B). Of the

physicians found to be eligible for the

survey, 941 were in the short form panel

and 969 were in the long form panel. Of

the physicians providing at least one PRF,

646 completed 12,872 short forms and

606 completed 11,409 long forms. Among

physicians with full or adequate response,

the unweighted response rate was

67.7 percent for the short form and

61.2 percent for the long form.

A total of 479 hospitals were

selected in the 2001 NHAMCS sample.

After sample selection, hospitals were

randomly assigned to one of two panels;

239 were in the short form panel and

240 were in the long form panel. Of the

hospitals with eligible OPDs, 132 were

in the short form panel and 129 were in

the long form panel. Of the clinics

selected from eligible OPDs, 548 were

administered the short form (Form A)

and 618 were administered the long

form (Form B). Among OPD clinics

providing at least one PRF, 492

completed 17,236 short forms and 544

completed 16,331 long forms. The

overall unweighted OPD response rate is

the product of the response rate for

OPDs and the response rate for OPD

clinics. This rate was 73.5 percent for

the short form and 73.9 percent for the

long form.

Data Collection

The U.S. Census Bureau was

responsible for data collection for the

2001 split-panel study. The Census

Bureau trained field representatives

(FRs) who, in turn, coordinated data

collection from physicians and hospitals.

To minimize the potential for

interviewer bias (biases introduced by

interviewers against the long form in

favor of the short form) on the

split-panel study, FRs for each survey

were trained at two large-scale training

conferences in Atlanta and New Orleans

during November 2000. FRs were

trained to use the two forms along with

exercises in how they would abstract the

data for each form. The fielding of two
Series 2, No. 139 [ Page 5

different forms was not presented as a

test (3). FRs were also told that

substitution of forms could not be made

for any reason and that doing so would

void the sample case (1). To ensure

correct usage of the forms, the letter

‘‘A’’ for the short form or ‘‘B’’ for the

long form was preprinted adjacent to the

randomly assigned facility ID on the

facility induction forms for physician

offices (NAMCS) and hospitals

(NHAMCS).

Data processing and medical coding

operations were performed by the

Constella Group, formerly Analytical

Sciences, Inc., Durham, North Carolina.

Separate keying and coding specifications

were provided for each panel of the

NAMCS and NHAMCS. These included

extensive instructions designed to map

write-in responses from the short form to

the corresponding check box categories on

the long form whenever possible.

Weighting and Estimation

Because the split-panel study took

place with the production samples of the

NAMCS and NHAMCS, survey-specific

weights utilizing both half samples were

developed for published reports. Weights

were also developed for each half

sample to independently yield national

estimates. This report presents estimates

based exclusively on these half sample

weights. Physician unit response rates

for the NAMCS were based on the final

disposition of physicians at the

induction stage. Although unweighted

physician response rates were described

in the previous section, ‘‘Split-panel

Sample Design,’’ they were not tested

for significance because unweighted

response rates reflect only the sample

cases, and differences cannot be

generalized to the entire population of

physicians. Consequently, only weighted

physician response rates are analyzed in

this report so that differences in

response can be generalized to all

physicians. Standard errors that take into

account the complex design of the

survey were calculated and used to test

differences between the half samples.

Similar to the NAMCS, only

weighted response rates for NHAMCS

outpatient departments, clinics (within

outpatient departments), and overall

response were analyzed. The weight for

analyzing hospital outpatient department

response rates is the reciprocal of the

probability of hospital selection. The

weight for hospital outpatient clinic

response rates is the product of the

reciprocal of the probability of hospital

selection and the reciprocal of the

probability of outpatient clinic selection

within the hospital.

In this report, visit estimates have

been rounded to the nearest thousand.

Visit estimates are not presented if they

are based on fewer than 30 sample

visits. When this occurred, only an

asterisk (*) appears in the tables.

Estimates based on 30 or more visits

include an asterisk when the relative

standard error (standard error expressed

as a percentage of the estimate)

exceeded 30 percent.

Analysis

Survey cooperation was measured

by provider unit response rates and item

nonresponse rates. The unit response

rate for the NAMCS and NHAMCS is

generally defined as the number of

sampled providers responding divided

by the sum of responding and refusing

providers. Response is defined as

providing at least 50 percent of the

PRFs expected to be completed during

the reporting period. The expected

number of sample visits is the product

of the sampling rate assigned to the

provider and the total number of visits

occurring in the randomly assigned

reporting period. Physicians, OPDs, or

OPD clinics providing no or minimal

response (PRFs obtained for less than

50 percent of the expected number of

sampled visits) were considered as

refusing to respond. The overall

weighted OPD response rate is the

product of the OPD response rate and

clinic response rate.

‘‘Item nonresponse’’ is defined as

the percent of PRFs with no valid

response, including a response of

‘‘unknown,’’ to a questionnaire data item

among completed PRFs. The range of

NAMCS item nonresponse rates

evaluated in this report was 0.8 to

36.2 percent; the range of NHAMCS

item nonresponse rates was 0.0 to

50.7 percent.

Standard error estimates for

physician, outpatient department, and

outpatient clinic unit response rates,

item nonresponse rates and visit

estimates were computed using

SUDAAN software (6) so that the

complex sample designs of the NAMCS

and NHAMCS were taken into account.

The standard error of the overall OPD

response rate was derived from the

relative variance formula for the product

of two random variables (7), under the

assumption of perfect correlation

between the department and clinic

response rates (since all responding

clinics were included within responding

departments). This assumption was

made because no clinic information was

available for outpatient departments that

did not participate in the survey. The

standard errors of overall outpatient

department and clinic response rates

should be considered maximums for

these estimates, due to the missing

information from nonresponding

outpatient departments.

In this report, chi-square tests of

association were performed to detect

significant associations between form

length and provider characteristics for

weighted unit response rates (physician,

OPD, and clinic) using the SUDAAN

routine PROC CROSSTAB. Because

this test only indicates that an

association exists between form length

and a characteristic, the odds of

response to the short over long form

(odds ratio) were calculated to identify

individual characteristics significantly

affecting response by form length. All

other tests of statistical significance

between estimates from the short and

long forms (overall OPD unit response

rate, item nonresponse rate, and visit

estimates) were based on the two-tailed

t-test at the 0.05 level of significance,

unless otherwise noted. Terms relating

to differences such as ‘‘greater than’’ or

‘‘less than’’ indicate that the difference

is statistically significant. A lack of

comment regarding the difference

between any two estimates does not

mean that the difference was tested and

found to be not significant.
Page 6 [ Series 2, No. 139

Results

Effect on Provider

Response

Physician Response Rates

The weighted physician response

rate was higher for the short than for the

long form (67.6 percent versus

61.9 percent). The odds of response

were more likely for the short than the

long form among general and family

practice physicians (OR=1.78), among

physicians in solo practice (OR=1.54),

and among ‘‘Other’’ practice types

(OR=5.91) (table 1).

Response also varied by geographic

location of the physician practice.

Response was lower for the short than

for the long form in the geographic area

administered by the Chicago Census

regional office (OR=0.50). Response

was higher for the short than for the

long form, however, in areas

administered by the Boston (OR=1.98)

and the Los Angeles Census regional

office (OR=2.40). Consequently,

differential response favoring the short

form was also observed in the Northeast

(OR=1.65) and the West (OR=1.79).

Response was also higher for the short

form in physician practices located in

MSAs (OR=1.30).

To simultaneously account for

differences in response between forms

and physician characteristics, a logistic

regression was performed. When using

this model, response to the short form

was 29 percent higher than response to

the long form overall, controlling for

physician specialty, type of practice,

region, and MSA status (data not

shown).

Hospital Outpatient

Department and Clinic

Response Rates

Weighted response rates at the OPD

and clinic levels, as well as for OPDs

overall, were examined for patterns of

response (tables 2–4). At the OPD level,

response favored the long form

(95.2 percent) over the short form

(87.9 percent) at the 0.10 level of

significance. The odds of response also

favored the long form over the short

form in general and specialty hospitals

(OR=0.39) at the 0.10 level of

significance and among hospitals located

in the West (OR=0.09) (table 2).

Response varied by teaching hospital

status. Among teaching hospitals,

response favored the short form

(OR=5.04). Among nonteaching

hospitals, however, OPD response

favored the long over the short form

(OR=0.18). The associations found for

these characteristics were significant at

the 0.10 level. The lower power of these

tests may be due to the small number of

sampled hospitals with OPDs (261

hospitals). OPD response rates were not

examined among the 12 interviewer

administrative regions (Census regional

offices) because sample sizes within

each administrative region were not

large enough to support such detailed

analysis.

At the clinic level, the weighted

response rate for the short form

(85.9 percent) was similar to that for the

long form (89.7 percent). There were no

significant differences in response

between forms among the hospital and

clinic characteristics shown in table 3

due to the small number of cases

limiting statistical power.

The overall OPD response rate

(incorporating response at the OPD and

clinic levels) was 85.4 percent for the

long form compared with 75.5 percent

for the short form (table 4). Although

the difference between these two rates

appears to be large, the two rates were

not statistically different at the 0.05

level of significance (4). Overall

response was significantly higher for the

long form in the mid-sized hospitals

with 100–199 beds (98.8 percent

compared with 79.4 percent for the short

form) and in nonteaching hospitals

(83.9 percent compared with

64.1 percent for the short form).

Effect on Item Nonresponse

As in any survey, results are subject

to both sampling and nonsampling

errors. Nonsampling errors include unit

and item nonresponse, as well as

reporting and processing errors. Both

unit and item nonresponse rates are

measures of survey quality. Item

nonresponse occurs when the needed

information is not available in the

medical record and/or is unknown to the

person filling out the survey instrument.

Nonresponse can also result when the

information is available, but survey

procedures are not followed and the

item is left blank.

Item nonresponse was evaluated to

determine whether the long form was

associated with higher levels of

nonresponse than the short form overall.

Item nonresponse rates were also

examined for differences by location on

the form (back of the long form versus

front of the short form).

Item Nonresponse by Form

Length

When physicians and hospital OPDs

decided to participate, the patterns of

nonresponse for the 24 questionnaire

items common to both forms were very

similar (table 5). The only exceptions to

this general trend occurred for two

NAMCS items (patient sex and visit

diagnosis) and one NHAMCS item

(patient sex). The direction of these

differences was lower rates of missing

data for the long form. In both cases, it

appears that related items on the long

form helped the abstractor to complete

the items more fully. In addition to the

item on sex, the long form requested the

associated item ‘‘If female, was the

patient pregnant?’’ and, in addition to

diagnoses rendered, the long form

requested abstractors to check any of

eight chronic conditions (e.g., asthma,

depression) that the patient had.

There were no significant

differences in item nonresponse rates

among the five items with more check

boxes on the long than the short form:

diagnostic and screening services;

counseling, education, and therapy;

surgical procedures; visit disposition;

and providers seen (table 5).

‘‘Medications and Injections’’ was the

only item with a different number of

maximum line entries (six on the short

form versus eight on the long form).

Item nonresponse rates for medications

and injections were also similar between

forms.
Series 2, No. 139 [ Page 7

Item Nonresponse by Location

on Form

Because the NAMCS and

NHAMCS have traditionally used

one-sided forms, one might expect

higher nonresponse for questions located

on the back of the long form.

Nonresponse rates, however, were

similar across forms for comparable

items located on the front of the short

form and on the back of the long form

in both settings. The nonresponse

rate (4) for all subitems located on the

back of the NAMCS long form

(3.9 percent) was statistically similar to

the nonresponse rate for comparable

subitems located on the front page of

the NAMCS short form (4.6 percent).

The NHAMCS OPD nonresponse rates

for the subitems located on the back

page of the long form (2.0 percent) was

also similar to the nonresponse rate for

the comparable short form front page

items (2.4 percent) (table 5). Items

included on the back of the long form

covered the following topics:

counseling, education, and therapy;

surgical procedures, number and type of

medications; visit disposition; providers

seen; and, for NAMCS only, time spent

with physician and time spent with other

providers.

Effect on Visit Estimates

The 2001 NAMCS/NHAMCS

split-panel study tested the effects of the

longer form on the likelihood of

reporting visit characteristics. A major

feature tested was the availability of

more response options on the long than

the short form. As described in the

section, ‘‘Split-panel Questionnaire

Design,’’ five items on the long form

included more check boxes than

comparable items on the short form.

Estimates for these items are presented

in tables 6–11.

Number of Response Options

It was hypothesized that the

availability of more response options on

the long form, either in the form of

check boxes or line entries, would result

in increased proportions of visits

reporting any service. However, this did

not occur for the diagnostic and

screening services item (table 6). The

short form estimate of at least one

diagnostic or screening service

(83.5 percent) in physician offices was

similar to the long form estimate (81.5).

The percentages of visits reporting one

or more diagnostic or screening services

were also similar between forms in

OPDs (87.7 percent for the short form

compared with 82.0 percent for the long

form).

There were no differences between

forms in the proportion of visits

reporting one or more surgical

procedures (table 7); one or more

counseling, education or therapeutic

services (table 8); one or more visit

dispositions (table 9); or one or more

providers seen (table 10). Although more

medications could be collected per visit

on the long form, there were also no

significant differences in the proportion

of visits with any drug mentioned

between forms in physicians offices

(62.5 percent for the short form

compared with 60.9 percent for the long

form) or in hospital OPDs (62.4 percent

for the short form compared with

67.0 percent for the long form)

(table 11).

It was expected that the greater

number of check boxes on the long

form would result in more services

being marked so that the number of

services mentioned on the short and

long forms should differ. There was a

shift in number of diagnostic and

screening services ordered or provided

in physician offices and OPDs between

forms (table A). Among physician office

and OPD visits, there were more visits

with six or more diagnostic or screening

services reported using the long (10.4

and 7.0 percent, respectively) than the

short form (3.7 and 3.5 percent,

respectively). When at least one service

was ordered or provided in physician

offices, the average reported was also

higher for the long (2.9 services) than

the short form (2.4 services). There

were no differences between forms in

the distributions of number of

counseling, education, or therapeutic

services in either setting (table B).

Although more medications could

be listed on the long than on the short

form, the percent of visits with six or

more medications using the NAMCS

long form (6.8 percent) was similar to

the short form (6.2 percent). Similar

findings also occurred in OPDs. It is of

interest that 4.7 percent of physician

office visits and 6. 6 percent of OPD

visits had 7–8 medications reported

using the long form. This suggests that

collection of more medications is

feasible.

When at least one medication was

provided or prescribed, the average

number of medications listed was

similar between forms in physician

offices (2.4 for each form) and in

hospital OPDs (2.3 and 2.4) (table 11).

It should be noted that although a

separate question asking for the total

number of medications provided or

prescribed was included on both forms,

the average total number of drugs

reported from that question was similar

to averages obtained from counting the

number of drugs listed, regardless of

form length or setting (table 11).

Write-in Responses Versus

Check Boxes

A major format difference between

the long and the short forms involved

the use of write-in response boxes. That

is, the long form item on diagnostic and

screening services used only check

boxes, and the short form used fewer

check boxes and had ‘‘other, specify’’

write-in response boxes for selected

categories of services (examinations,

cultures, scope procedures, and a

residual ‘‘other services’’). The latter

feature permitted reporting diagnostic

and screening services not included

among the short form check boxes. The

write-in entries, in turn, were used to

create recodes that could be compared

with long form check box data. The

recodes also increased the amount of

comparable data that could be published

in reports using both panels of data

(4,5). Estimates based on recodes from

short form write-in responses are

compared with estimates based on long

form check boxes for selected diagnostic

and screening services (table 7).

The format of the surgical

procedures item also varied between

forms. The short form item on surgical

procedures included only two write-in
Page 8 [ Series 2, No. 139

Table A. Percent of visits to ambulatory care settings with standard errors, by number of diagnostic and screening services ordered or

provided and form length: Split-panel study, 2001

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Number of diagnostic and screening

services ordered or provided

Short

form

Long

form

Short

form

Long

form

Short

form

Long

form

Short

form

Long

form

Percent of visits Standard error of percent

1 or more diagnostic or screening

services ........................ 83.5 81.5 87.7 82.0 1.4 1.5 1.7 2.4

1 service ....................... 28.5 31.1 31.6 31.7 1.3 1.6 2.6 2.3

2 services1 ...................... 27.2 15.9 26.2 18.1 1.4 0.9 1.6 1.3

3 services ...................... 12.6 12.2 13.9 12.7 0.6 0.9 1.0 1.0

4–5 services ..................... 11.5 11.9 12.5 12.5 0.8 1.2 1.8 1.3

6 services or more1 ................ 3.7 10.4 3.5 7.0 0.5 1.0 0.5 1.0

1Difference between short and long form percentage is statistically significant at the α=0.05 level for National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey.

Table B. Percent of visits to ambulatory care settings with standard errors, by number of counseling, education, or therapeutic services

ordered or provided and form length: Split-panel study, 2001

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Number of counseling, education, or Short Long Short Long Short Long Short Long

therapeutic services ordered or provided form form form form form form form form

Percent of visits Standard error of percent

1 or more counseling, education, or therapeutic

services ........................ 39.9 43.4 39.3 47.9 2.0 2.5 3.1 3.7

1 service ....................... 27.0 28.3 26.9 31.5 1.4 1.7 2.0 2.7

2 services ...................... 8.3 8.9 9.1 10.7 0.7 1.2 1.3 1.3

3 services or more ................. 4.5 6.2 3.3 5.7 0.6 0.8 0.6 1.0

entry lines, and the long form item

included four check boxes and two

write-in entry lines. Data from the short

form write-in entries were also recoded

into categories comparable to the four

long form check boxes for the following

surgical procedure categories: none,

biopsy, excision of tissue, and suture

removal. Visit estimates based on these

two formats are also presented in

table 7.

Visit estimates based on write-in

responses were often lower than

estimates based on check boxes. In

physician offices, the percentage of

visits based on check boxes was

significantly higher than the comparable

percentage based on write-in responses

for six types of examinations (rectal,

skin, eye, ear, mental status, and

neurological examinations), blood

glucose level, visual acuity tests, and

suture removal.

A similar pattern was also noted

among visits to OPDs, where visit

percentages based on check boxes

exceeded estimates based on write-in

responses for eight types of

examinations and two tests. The ratio of

visit estimates based on check box (long

form) versus write-in responses (short

form) is shown in figure 3. Ratios of

long over short form estimates ranged

from 2.8 for rectal exams in physician

offices to 93.0 for mental status exams

in OPDs (figure 3).

Differences in visit estimates based

on check box versus write-in formats

are due to the explicit information

requested in the check-box wording,

compared with the parenthetical

examples provided as probes with

write-in response boxes. For example,

the long form check boxes for eight

types of examinations (breast, pelvic,

rectal, skin, eye, ear, mental status, and

neurologic) explicitly requested these

examinations, and the short form

provided only two examples in the

probe ‘‘(e.g., breast, rectal)’’ for the

‘‘other exam—specify’’ write-in

responses.

However, estimates produced by

these two methods for several other

services were not significantly different.

For example, similar visit percentages

were obtained in physician offices for

throat or rapid strep-test cultures,

ultrasound, cardiac stress test,

sigmoidoscopy/colonoscopy, cystoscopy,

no surgical procedures, biopsy, and

excision of tissue. Similar estimates in

hospital OPDs were found for

cervical/urethral cultures, no surgical

procedures, and excision of tissue. This

suggests that write-in response boxes

may be an efficient way to collect

data for certain tests or procedures, but,

in general, write-in response boxes can

significantly underestimate visits

for a large number of tests and

procedures.

Question Wording and Item

Format

Visit estimates based on check

boxes also varied by question wording

or probes associated with the check box

and item format, including whether the

item was located on the front or back of

the form.

As described in the last section, the

short form included check boxes and
Series 2, No. 139 [ Page 9

Figure 3. Ratio of long form to short form estimate for selected diagnostic and screening services by survey: Split-panel study, 2001

spaces for write-in entries for type of

examination (excluding general medical

examination), culture, scope procedure,

and other services; and the long form

included check boxes for specific

services within these procedure

categories. The specificity of the

wording associated with the long form

check boxes increased reporting for

some of these services. For example, the

short form percentage of visits reporting

any culture was based on a single check

box labeled ‘‘Culture (e.g., throat)—

specify’’ with a write-in box, and the

closest derived estimate from the long

form is based on response to any of four

check boxes (‘‘Cervical/Urethral,’’

‘‘Stool,’’ ‘‘Throat/Rapid strep test,’’ and

‘‘Urine’’) without a write-in response

box (figure 4). In both physician offices

and hospital OPDs, the check-box

format of the long form yielded higher

proportions of visits with cultures (4.3

and 5.6 percent, respectively) than

reported on the short form (2.5 and

3.0 percent, respectively).

It was also possible that long form

visit estimates might be lower than

comparable short form estimates for

items located on the back page of the

long form, but on the front of the short

The short form percentage of physician

office visits with asthma education was

significantly higher than the long form

percentage (2.0 percent versus

0.9 percent of long form visits). This

was also found for physiotherapy

(2.3 percent versus 0.7 percent).

However, wording for these check boxes

was identical, and nonresponse rates for

these items were similar between forms

(table 8). There were no significant

differences in percentages of OPD visits,

however, by individual categories of

counseling, education or therapy by

form (table 8). There were also no

differences between forms in the

percentage of visits by individual

categories of providers seen (table 9) or

visit disposition (table 10) in either

physician offices or OPDs. Both of

these items were located on the back

page of the long form.

form. This did occur for selected items. Figure 4. Percent of visits with any culture ordered or collected by form length and survey:

Split-panel study, 2001
Page 10 [ Series 2, No. 139

Type of Respondent

Across both forms in the NAMCS

and NHAMCS, about half of the PRFs

were completed by physicians and/or

their staff (51.0 percent) or hospital staff

(47.2 percent), respectively. About

13.1 percent of PRFs were jointly

completed by the FR and physicians and

their staff, and 8.5 percent of PRFs were

jointly completed by the FR and

hospital OPD staff (data not shown).

Overall, patterns of questionnaire

completion by respondent type did not

vary between panels in either setting

(figures 5 and 6).

Although there were few differences

in respondent types by panel, differences

could occur if certain services were not

always recorded on the medical record. Figure 5. Percent of office visits by respondent type and form length: Split-panel study,

A previous study found that physician 2001

recording of health habit counseling on

the medical records was lower than the

rate of advice found by direct

observation, but physician recording of

procedures and examinations had high

validity with direct observation (8).

Consequently, it might be hypothesized

that reporting by physicians or their

staff versus FR abstraction would differ

for counseling and procedural services

because physicians and their staffs could

report from personal knowledge, but

FRs could not. This occurred in the

NAMCS; there were no differences in

the percentage of visits with one or

more diagnostic and screening services

by type of respondent, but the

percentage of visits with at least one

type of counseling, education, or therapy

ordered or provided was lower when

FRs abstracted the data (figure 7).

Feasibility of Collecting

Data Items Specific to the

Long Form

Finally, another goal of the

split-panel study was to test the

feasibility of capturing more

detailed survey content by including

seven additional items on the long form.

The following five items had never been

collected in the NAMCS and OPD

component of the NHAMCS: type of

insurance plan, blood pressure reading

(if blood pressure test was indicated),

Figure 6. Percent of visits to hospital outpatient departments by respondent type and form

length: Split-panel study, 2001

check boxes for selected ambulatory

medical procedures, whether each

medication listed (up to eight) was a

new medication for the patient, and time

spent with providers other than a

physician (NAMCS only). The

following two items were fielded in

previous rounds of the surveys: whether

the patient was pregnant (female only),

and presence of eight conditions

(regardless of physician diagnosis). Visit

estimates for these data items are

presented in table 12.

Nonresponse rates for the five new

items indicate the feasibility of

collecting these items in future rounds

of the NAMCS and NHAMCS

(figure 8). For example, when blood

pressure was taken, blood pressure

readings were almost never missing (i.e.,

data were missing for these variables in

3.0 and 0.7 percent of visits in physician
Series 2, No. 139 [ Page 11

Figure 7. Percent of office visits reporting one or more diagnostic or screening services and one or more counseling, education, or

therapeutic services by type of respondent: Split-panel study, 2001

offices and OPDs, respectively). The

distribution of visits by blood pressure

reading in physician offices was similar

to that found in OPDs (table 12).

Nonresponse to the additional surgical

procedure check boxes appearing only

on the long form seldom occurred in

either physician offices or OPDs.

The item on whether the medication

was new or continued was also

generally available in both settings; item

nonresponse rates were 9.0 percent in

physician offices and 10.6 percent in

OPDs, respectively (figure 8). Table 12

shows that about half of drug visits (i.e.,

visits with any mention of a drug) in

physician offices involved medications

new to the patient (52 percent), either

alone (37.4 percent) or in conjunction

with an old prescription (14.6 percent).

About 39 percent of drug visits in

physician offices involved only

previously prescribed medications.

Similar patterns of old and new

prescriptions were also found in OPDs.

The percentage of visits with

missing data for the new item on time

spent with nonphysician providers

(14.2 percent) was similar to the

percentage of visits with missing data

for time spent with physicians

(17.6 percent), an item collected every

year in the NAMCS (table 5). In 2001,

providers other than physicians were

seen in 73.7 percent of visits (calculated

from table 12). They may have been

seen alone or in addition to the

physician. The average time spent with

physicians (18.3 minutes) was

significantly longer than the average

time spent with nonphysician providers

(9.3 minutes). These averages excluded

missing data for each item, as well as

cases in which a physician or

nonphysician provider was not seen.

The percentage of visits missing

data for type of health insurance plan

was higher in OPDs (30.7 percent) than

in physician offices (16.4 percent). Type

of health insurance plan may have been

missing more often in OPDs because

visits to this setting were less likely to

be insured by one of the listed types of

health plans (30.6 percent) than visits to

physician offices (66.1 percent)

(calculated from table 12).

Check boxes indicating pregnant

females have been collected in previous

years of the NAMCS and NHAMCS.

However, the 2001 nonresponse rate for

this item was lower than in previous

years. For example, the percentage of

missing data for this item in physician

offices was 15.8 percent in 2001 and

24.7 percent in 2000 (9). The OPD

nonresponse rate for this item was

20.3 percent in 2001 and 34.8 percent in

2000 (10).

Information identifying patients

with selected conditions can be used to

track trends in utilization of physician

offices and hospital OPDs by patients

with these conditions, as well as to

provide context for utilization patterns.

In addition, data from the condition

check boxes provide more complete

reporting of these conditions because

physician diagnoses were limited to

three and to those related to the current

visit. Since 1995, the percent of office

visits by patients with hypertension

increased by 18.8 percent (from 14.9 to

17.7 percent), visits by patients with

diabetes increased by 33.3 percent (from

5.7 to 7.6 percent), and visits by patients

with depression increased by

31.5 percent (from 5.4 to

7.1 percent) (11). The 2001 percent of

missing data for chronic conditions was

14.4 percent in physician offices and

8 percent in OPDs.

Conclusions

I

n this study, PRF instrumentation

effects, including both form length

and item formats, were tested.

The study found that form length had

mixed effects on the quality of the data

as measured by unit and item

nonresponse. Form length affected

overall physician response negatively

(61.9 percent for the long form

compared with 67.6 percent for the short

form), but had no effect on OPD

response. Although there was a

difference in outpatient department

response favoring the long form at the

0.10 level of significance, there were no

differences at the clinic level or overall

(combining response at both the

department and clinic level). A few
Page 12 [ Series 2, No. 139

Figure 8. Weighted item nonresponse rates for data items collected only on long form by survey: Split-panel study, 2001

differences occurred favoring the long

over the short form in some types of

hospitals. It is of interest that although

overall response to the long form in

OPDs was not significant, the direction

of response favored the long form over

the short form. The response patterns

between forms observed in OPDs was

probably affected by small cell sizes.

Overall, only 54 percent (n=261) of

sampled hospitals had eligible OPDs.

The lower response associated with the

NAMCS long form suggests that the

continued use of the one-sided form

traditionally administered in the

NAMCS and OPD component of the

NHAMCS is warranted.

For the most part, item nonresponse

rates for the 24 questionnaire items

common to both forms were similar,

although some significant differences

were observed by setting. These

differences (patient sex and visit

diagnosis) were associated with lower

nonresponse for these items on the long

form. Items located on the back page of

the long form were completed as

frequently as on the front page of the

short form. These results, however, do

not factor in the increased time required

by FRs to call back long form

respondents for missing information nor

costs associated with call backs.

There were mixed results on

reporting levels for long form items

with more response options. For

example, there was evidence that having

more check boxes on the long form’s

diagnostic or screening services item

was associated with an increase in

number of services reported, but the

same was not true for the long form’s

counseling, education, or therapeutic

services item. There was also no

difference in distributions of number of

medications between forms despite

eight, rather than six, medications

collected on the long form. Similar

reporting was also observed between

forms for the following data items:

surgical procedures, visit disposition,

and providers seen. These items also

had more response options on the long

than the short form.

The format of the items appeared to

have a larger effect on estimates than

the question wording of check boxes.

Multiple check boxes for a type of

service on the long form, such as types

of specific cultures, yielded more visits

with these services than did a single

check box with write-in entries on the

short form. A few items located on the

back of the NAMCS long form had lower

reporting than comparable items located

on the front page of the short form

(asthma education and physiotherapy).

The study found that estimates based on

write-in responses were generally lower

than the corresponding estimates based on

check boxes.

Finally, this study found that some

long form specific items could be

successfully collected. The feasibility of

listing eight instead of six medications,

asking if the recorded medication was

new to the patient, and collecting blood

pressure readings was demonstrated.

Collecting information on the type of

health insurance plan was problematic in

OPDs; about a third of visits were

missing data for this item.

Form-specific estimates presented in

this report will differ from estimates

derived from the 2001 NAMCS and

NHAMCS public use files because

estimates presented in this report were

derived using panel-specific weights

designed to produce nationally

representative visit estimates. In

contrast, the patient weights included on

the NAMCS and NHAMCS public use

files were designed to include both

panels of each respective survey to

produce nationally representative visit

estimates (12,13).
Series 2, No. 139 [ Page 13

References 11. Woodwell DA. National Ambulatory

Medical Care Survey: 1995 summary.

Advance data from Vital and Health

1. Schappert S. Draft analysis plan for the

2001 NAMCS/NHAMCS split-panel

surveys. Unpublished memo dated

October 3, 2000. 12.

Statistics; no. 286. Hyattsville,

Maryland: National Center for Health

Statistics. 1997.

National Center for Health Statistics.

2.

3.

Groves R. Survey errors and survey

costs. New York: John Wiley & Sons,

Inc. 1989.

Burt CW, Schappert SM, Hing E.

Lessons learned from a split-panel test

on questionnaire length for a providerbased health survey. In 2003

Proceedings of the Section on Survey

Research Methods, American Statistical

Association. Alexandria, VA: American

Statistical Association: 743–8. 2004.

13.

Public Use Data File Documentation:

2001 National Ambulatory Medical

Care Survey. Hyattsville, Maryland:

National Center for Health Statistics.

2003.

National Center for Health Statistics.

Public Use Data File Documentation:

2001 National Ambulatory Hospital

Medical Care Survey. Hyattsville,

Maryland: National Center for Health

Statistics. 2003.

4. Cherry D, Burt, CW, Woodwell DA.

National Ambulatory Medical Care

Survey: 2001 summary. Advance data

from Vital and Health Statistics; no.

337. Hyattsville, Maryland: National

Center for Health Statistics. 2003.

5. Hing E, Middleton K. National

Hospital Ambulatory Medical Care

Survey: 2001 outpatient department

summary. Advance data from Vital and

Health Statistics; no. 338. Hyattsville,

Maryland: National Center for Health

Statistics. 2003.

6. Research Triangle Institute. SUDAAN

user’s manual release, release 8.0.

7.

Research Triangle Park, NC: Research

Triangle Institute. 2002.

Hansen MH, Hurwitz WN, Madow

WG. Sample Survey Methods and

Theory. New York: John Wiley & Sons,

Inc. 1992.

8.

9.

Gilchrist VJ, Stange KC, Flocke SA,

McCord G, Bourguet CC. A

comparison of the National Ambulatory

Medical Care Survey (NAMCS)

measurement approach with direct

observation of outpatient visits.

Medical Care 42(3):276–80. 2004.

Cherry D, Burt CW, Woodwell DA.

National Ambulatory Medical Care

Survey: 2000 summary. Advance data

from Vital and Health Statistics; no.

328. Hyattsville, Maryland: National

Center for Health Statistics. 2002.

10. Ly N, McCaig L. National Hospital

Ambulatory Medical Care Survey: 2000

outpatient department summary.

Advance data from Vital and Health

Statistics; no. 327. Hyattsville,

Maryland: National Center for Health

Statistics. 2002.
Page 14 [ Series 2, No. 139

Table 1. Sample size and weighted physician response rate by form length and selected physician characteristics, with standard error of

rate, unadjusted odds ratio, and 95% confidence interval of odds ratio: Split-panel study, 2001

Response rate Standard error of rate 95% confidence

Sample Unadjusted interval of

Physician characteristic size Short form Long form Short form Long form odds ratio1 odds ratio

All physicians2 ................... 1,910 67.6 61.9 2.0 2.1 1.29 (1.02 – 1.61)

Specialty2

General and family practice ........... 193 71.8 58.9 4.6 5.2 1.78 (1.01 – 3.12)

Internal medicine ................. 140 62.7 65.3 6.6 5.6 0.89 (0.43 – 1.83)

Pediatrics ...................... 121 77.3 69.8 5.3 6.1 1.47 (0.62 – 3.51)

General surgery .................. 105 70.0 60.1 6.5 7.5 1.55 (0.66 – 3.60)

Obstetrics and gynecology ........... 125 66.5 51.7 6.3 6.8 1.86 (0.82 – 4.18)

Other ......................... 1,226 65.3 62.1 2.7 2.7 1.15 (0.85 – 1.55)

Type of practice2

Solo ......................... 632 65.4 55.2 3.2 3.9 1.54 (1.02 – 2.32)

Partnership ..................... 151 77.9 65.8 5.5 7.4 1.84 (0.77 – 4.34)

Group or HMO3 .................. 672 65.2 66.0 3.3 3.4 0.96 (0.63 – 1.47)

Medical school or government ......... 40 83.9 68.3 7.7 12.5 2.43 (0.47 –12.57)

Other ......................... 38 91.4 64.3 4.7 11.3 5.91 (1.24 –28.15)

Unclassified .................... 377 67.9 62.9 4.4 4.6 1.25 (0.68 – 2.28)

Census regional office2

Boston ........................ 160 65.8 49.2 4.9 6.3 1.98 (1.13 – 3.47)

New York ...................... 178 58.2 46.1 7.0 6.1 1.63 (0.76 – 3.49)

Philadelphia .................... 201 54.1 52.8 6.4 5.6 1.05 (0.52 – 2.15)

Detroit ........................ 154 74.8 71.0 5.8 5.9 1.21 (0.62 – 2.36)

Chicago ....................... 164 59.8 75.0 7.0 6.1 0.50 (0.26 – 0.94)

Kansas City .................... 143 75.9 81.2 7.2 4.4 0.73 (0.30 – 1.77)

Seattle ........................ 129 71.7 69.3 7.0 6.4 1.12 (0.45 – 2.80)

Charlotte ...................... 138 69.0 59.4 5.4 8.0 1.52 (0.72 – 3.21)

Atlanta ........................ 126 83.6 86.5 5.0 4.9 0.80 (0.25 – 2.55)

Dallas ........................ 200 63.6 52.8 6.0 6.0 1.56 (0.80 – 3.04)

Denver ........................ 133 77.8 71.9 6.7 7.7 1.37 (0.57 – 3.30)

Los Angeles .................... 184 68.3 47.3 5.7 5.5 2.40 (1.20 – 4.79)

Region2

Northeast ...................... 477 61.2 48.9 3.9 3.6 1.65 (1.08 – 2.52)

Midwest ....................... 385 66.7 74.8 4.5 4.2 0.68 (0.43 – 1.07)

South ........................ 616 68.0 63.7 3.5 3.8 1.21 (0.80 – 1.83)

West ......................... 432 74.4 61.9 4.0 4.6 1.79 (1.06 – 3.00)

Metropolitan status2

MSA4 ........................ 1,693 66.6 60.5 2.0 2.2 1.30 (1.04 – 1.63)

Not MSA4 ...................... 217 74.9 71.2 6.3 5.6 1.20 (0.54 – 2.70)

1Odds ratio of short form over long form response. Based on Cochran-Mantel-Haenszel chi-square test.

2Cochran-Mantel-Haenszel test of association is statistically significant at the α=0.05 level.

3HMO is health maintenance organization.

4MSA is metropolitan statistical area.
Series 2, No. 139 [ Page 15

Table 2. Sample size and weighted hospital outpatient department response rate by form length and selected hospital characteristics, with

standard error of rate, unadjusted odds ratio, and 95% confidence interval of odds ratio: Split-panel study, 2001

Outpatient department response rate Standard error of rate 95% confidence

Sample Unadjusted interval of

Hospital characteristic size Short form Long form Short form Long form odds ratio1 odds ratio

All outpatient departments2 ........... 261 87.9 95.2 3.8 1.6 0.37 (0.14 – 0.98)

Type of hospital2

General medical and surgical .......... 236 88.8 95.4 4.0 1.7 0.39 (0.13 – 1.15)

Specialty hospital ................. 25 80.6 93.7 12.8 6.8 0.28 (6.02 – 4.52)

Hospital size

Under 100 beds .................. 50 86.3 96.5 7.5 2.5 0.23 (0.03 – 1.66)

100 – 199 beds .................. 50 84.8 98.8 7.7 0.9 0.07 (0.01 – 0.47)

200 or more beds ................. 161 90.7 87.4 3.3 3.7 1.41 (0.56 – 3.54)

Teaching hospital2

Yes .......................... 128 98.1 91.1 0.6 4.0 5.04 (1.58 –16.11)

No .......................... 133 83.4 96.6 5.3 1.7 0.18 (0.05 – 0.65)

Hospital ownership3

Voluntary, nonprofit ................ 171 84.8 94.1 6.1 2.2 0.35 (0.11 – 1.16)

Government, non-Federal ............ 40 85.3 97.9 8.8 2.1 0.12 (0.01 – 1.52)

Proprietary ..................... 50 93.3 97.7 4.8 1.6 0.32 (0.04 – 2.73)

Region2

Northeast ...................... 78 75.6 83.5 11.3 7.2 0.61 (0.15 – 2.52)

Midwest ....................... 66 97.6 97.5 2.0 1.3 1.04 (0.13 – 8.08)

South ........................ 80 89.9 96.7 4.5 1.9 0.31 (0.06 – 1.49)

West ......................... 37 78.5 97.7 12.2 1.1 0.09 (0.02 – 0.39)

Metropolitan status

MSA4 ........................ 232 89.1 92.8 3.0 2.2 0.64 (0.27 – 1.51)

Not MSA4 ...................... 29 85.4 97.7 9.7 2.3 0.14 (0.01 – 1.87)

1Odds ratio of short form over long form response. Based on Cochran-Mantel-Haenszel chi-square test.

2Cochran-Mantel-Haenszel test of association is statistically significant at the α=0.10 level.

3Cochran-Mantel-Haenszel test of association is statistically significant at the α=0.05 level.

4MSA is metropolitan statistical area.
Page 16 [ Series 2, No. 139

Table 3. Sample size and weighted hospital outpatient department clinic response rate by form length and selected hospital and clinic

characteristics, with standard error of rate, unadjusted odds ratio, and 95% confidence interval of odds ratio: Split-panel study, 2001

Outpatient department clinic response rate Standard error of rate 95% confidence

Sample Unadjusted interval of

Hospital characteristic size Short form Long form Short form Long form odds ratio1 odds ratio

All outpatient department clinics ........ 1,166 85.9 89.7 3.7 2.6 0.70 (0.30 – 1.63)

Clinic type

General medicine ................. 386 86.6 88.4 4.2 4.3 0.85 (0.28 – 2.54)

Surgery ....................... 245 84.7 90.8 6.0 3.3 0.56 (0.16 – 1.95)

Pediatrics ...................... 211 78.3 96.4 9.8 1.6 0.14 (0.13 – 0.62)

Obstetrics and gynecology ........... 154 91.5 86.9 3.5 4.8 1.62 (0.48 – 5.51)

Substance abuse ................. 18 93.6 100.0 6.9 . . . . . . . . .

Other ......................... 152 92.6 80.4 4.3 4.3 3.04 (0.75 – 12.27)

Type of hospital

General medical and surgical .......... 1,073 86.4 88.4 3.7 3.0 0.84 (0.35 – 1.97)

Specialty hospital ................. 93 82.0 98.2 15.1 1.5 0.08 (0.01 – 1.20)

Hospital size

Under 100 beds .................. 100 94.9 88.4 4.2 6.1 2.44 (0.30 – 19.59)

100–199 beds ................... 181 98.1 95.3 1.5 1.7 2.59 (0.42 – 16.14)

200 beds or more ................. 885 83.5 87.5 4.7 4.2 0.72 (0.26 – 2.05)

Teaching hospital

Yes .......................... 713 91.1 93.6 3.6 2.0 0.70 (0.22 – 2.18)

No .......................... 453 76.9 86.9 6.5 4.3 0.50 (0.17 – 1.44)

Hospital ownership

Voluntary, nonprofit ................ 749 86.2 91.3 4.7 2.8 0.59 (0.21 – 1.71)

Government, non-Federal ............ 249 90.4 78.1 6.6 9.9 2.64 (0.38 – 18.58)

Proprietary ..................... 168 78.1 94.9 10.0 3.8 0.19 (0.03 – 1.34)

Region

Northeast ...................... 417 83.6 92.2 6.4 2.7 0.43 (0.13 – 1.47)

Midwest ....................... 297 99.6 93.7 0.4 1.9 17.96 (1.58 –204.10)

South ........................ 312 73.8 75.0 6.9 9.2 0.94 (0.26 – 3.31)

West ......................... 140 91.2 96.2 5.0 2.8 0.41 (0.06 – 2.97)

Metropolitan status

MSA2 ........................ 1,107 84.9 90.3 4.1 2.7 0.61 (0.25 – 1.49)

Not MSA2 ...................... 59 100.0 87.7 . . . 7.3 . . . . . .

. . . Not applicable.

1Odds ratio of short form over long form response. Based on Cochran-Mantel-Haenszel chi-square test.

2MSA is metropolitan statistical area.

NOTE: No Cochran-Mantel-Haenszel chi-square test was significant in this table.
Series 2, No. 139 [ Page 17

Table 4. Weighted overall hospital outpatient department response rate with standard error of rate, by form length and selected hospital

characteristics: Split-panel study, 2001

Overall response rate1 Standard error of overall response rate2

Hospital characteristic Short form Long form Short form Long form

Total ............................................ 75.5 85.4 5.7 4.2

Type of hospital

General medical and surgical ............................. 76.9 84.3 5.1 4.4

Specialty hospital .................................... 68.3 85.1 16.6 5.6

Hospital size

Under 100 beds ..................................... 79.0 83.8 7.2 8.6

100 – 199 beds3 .................................... 79.4 98.8 6.0 3.1

200 beds or more .................................... 84.0 70.3 7.3 4.6

Teaching hospital

Yes ............................................. 89.4 85.3 5.8 4.5

No3 ............................................. 64.1 83.9 8.2 6.7

Hospital ownership

Voluntary, nonprofit ................................... 73.1 85.9 7.4 4.6

Government, non-Federal ............................... 77.1 76.5 11.1 14.7

Proprietary ........................................ 72.9 92.7 14.2 6.4

Region

Northeast ......................................... 63.2 77.0 10.0 6.8

Midwest .......................................... 97.2 91.4 2.1 3.3

South ........................................... 66.3 72.6 9.2 13.2

West ............................................ 71.6 94.0 11.0 4.7

Metropolitan status

MSA4 ........................................... 75.7 83.8 5.9 4.4

Not MSA4 ......................................... 85.4 85.7 9.0 11.6

1Overall response rate is the product of the response rate for hospital outpatient departments and the response rate for outpatient department clinics divided by 100.

2For this analysis, the standard error of the overall response rate was derived from the relvariance formula for two random variables (8), under the assumption of perfect correlation between the

department and clinic response rates (since all responding clinics were included within responding departments). This assumption was made because no clinic information was available for outpatient

departments that did not participate in the survey.

3Difference between short and long form rate is statistically significant at the α=0.05 level.

4MSA is metropolitan statistical area.
Page 18 [ Series 2, No. 139

Table 5. Weighted item nonresponse rates and standard errors of rates by form length and survey: Split-panel study, 2001

Weighted item nonresponse rate Standard error of rate

NAMCS NHAMCS — OPDs NAMCS NHAMCS — OPDs

Variable Short form Long form Short form Long form Short form Long form Short form Long form

All items located on front of long form .... 8.0 8.0 9.9 10.5 0.5 0.5 0.7 0.9

Date of birth .................... 1.9 1.3 0.7 1.2 0.5 0.2 0.2 0.5

Zip code ....................... 2.3 2.5 3.8 3.4 0.6 0.5 1.1 1.2

Sex1 ......................... 3.7 1.3 3.9 1.6 0.4 0.2 0.6 0.5

Female pregnant?2 ................ . . . 14.1 . . . 20.3 . . . 1.3 . . . 3.1

Ethnicity ....................... 23.4 28.1 16.7 24.7 3.0 2.6 3.6 5.6

Race ......................... 19.7 20.9 15.6 20.1 2.7 2.7 3.1 6.2

Patient uses tobacco2 .............. 33.1 30.5 50.7 45.1 2.1 2.5 3.1 4.7

Type of insurance plan2 ............. . . . 16.4 . . . 30.7 . . . 2.0 . . . 3.5

Primary expected payment source ....... 4.2 3.7 6.1 7.1 0.8 0.4 0.9 1.5

Patient reason for visit .............. 1.4 1.8 1.2 1.3 0.5 0.6 0.5 0.3

Primary care physician .............. 5.2 5.0 13.0 13.9 0.9 0.7 2.9 2.7

Patient referred for this visit ........... 19.8 17.8 29.5 31.4 2.0 1.8 4.3 4.0

Patient seen before ................ 1.5 0.8 1.5 1.9 0.5 0.2 0.4 0.8

Visits last 12 months ............... 6.1 6.7 11.7 13.6 1.0 1.4 2.3 4.0

Major reason for visit ............... 6.5 3.6 4.1 4.6 1.3 0.6 0.8 1.4

Episode of care .................. 10.5 11.3 12.4 13.3 1.2 1.1 2.0 2.3

Other physicians share care .......... 13.9 14.6 24.2 27.2 1.8 1.4 3.1 4.2

Cause of injury ................... 36.9 36.2 31.5 25.7 2.5 2.9 3.7 2.3

Physician diagnosis3 ............... 3.3 1.1 2.0 1.3 0.7 0.2 0.3 0.4

Condition check list2 ............... . . . 14.4 . . . 8.0 . . . 2.1 . . . 1.5

Diagnostic or screening services ........ 1.2 1.7 0.8 1.1 0.4 0.4 0.2 0.2

Diastolic/systolic blood pressure ........ . . . 3.0 . . . 0.7 . . . 1.4 . . . 0.3

All items located on back of long form .... 4.6 3.9 2.4 2.0 0.5 0.4 0.5 0.2

Counseling, education, or therapy ....... 3.9 3.1 2.6 1.8 0.7 0.7 0.7 0.4

Surgery check list ................. . . . 4.3 . . . 0.0 . . . 0.7 . . . . . .

Surgical procedures ................ 12.0 7.4 9.6 7.6 1.7 1.7 2.4 3.0

Number of medications ............. 4.7 6.7 4.0 5.0 0.9 0.9 0.8 0.7

Medications and injections ........... 5.1 7.2 4.4 5.3 1.0 1.0 0.8 0.7

New medication check boxes2 ......... . . . 9.0 . . . 10.6 . . . 1.3 . . . 2.3

Visit disposition .................. 2.2 1.9 3.5 0.9 0.5 0.4 1.9 0.2

Providers seen ................... 1.0 1.3 1.6 1.7 0.5 0.5 0.6 1.0

Time spent with physician ............ 19.3 17.6 . . . . . . 2.7 2.4 . . . . . .

Time spent with other providers 2 ....... . . . 14.2 . . . . . . . . . 1.9 . . . . . .

. . . Category not applicable.

1Difference between short and long form rate is statistically significant at the α=0.05 level for both the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care

Survey.

2Item included only on long form.

3Difference between short and long form rate is statistically significant at the α=0.05 level for the National Ambulatory Medical Care Survey.

NOTE: NAMCS is National Ambulatory Medical Care Survey, NHAMCS is National Hospital Ambulatory Medical Care Survey, and OPD is outpatient department.
tory care settings with standard error of percent by form length, ratio of estimates, and selected diagnostic and screening services: Split-panel

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Short Long Ratio of Short Long Ratio of Short Long Short Long

form form estimates form form estimates form form form form

Percent of visits Percent of visits Standard error of percent

...... 15.3 16.8 1.1 11.5 16.9 1.5 1.3 1.5 1.7 2.3

...... 83.5 81.5 1.0 87.7 82.0 0.9 1.4 1.5 1.7 2.4

...... 50.3 8.9 0.2 52.9 6.1 0.1 2.2 1.5 4.0 1.1

...... 21.0 36.5 1.7 16.7 37.3 2.2 1.7 2.0 2.2 3.0

...... 4.8 5.3 1.1 3.1 2.4 0.8 0.7 0.8 0.4 0.4

...... 1.5 1.5 1.0 0.5 0.3 0.6 0.2 0.2 0.1 0.1

...... 2.5 2.5 1.0 2.6 1.7 0.7 0.7 0.4 0.5 0.4

...... 8.8 7.9 0.9 11.3 7.6 0.7 1.0 0.8 1.4 1.0

...... 3.6 3.4 0.9 2.9 3.1 1.1 0.5 0.7 0.4 0.5

...... 8.1 6.1 0.7 8.8 7.4 0.8 0.8 0.7 0.8 1.0

...... 6.4 5.9 0.9 6.3 8.2 1.3 0.7 0.6 0.8 1.4

...... 2.0 1.9 1.0 2.3 1.5 0.7 0.3 0.3 0.6 0.3

...... 3.3 2.2 0.7 5.3 2.6 0.5 0.3 0.2 1.1 0.4

...... 49.9 45.1 0.9 52.6 52.7 1.0 2.3 2.7 3.6 3.8

...... 2.5 2.9 1.1 2.6 1.9 0.7 0.3 0.4 0.5 0.4

...... 6.2 5.4 0.9 6.6 3.9 0.6 0.6 1.2 1.0 1.0

...... 1.2 1.7 1.4 0.8 1.1 1.4 0.4 0.4 0.2 0.2

m. Available data from the long form were mapped to approximate these check boxes.

s statistically significant at the α=0.05 level for both the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey.s statistically significant at the α=0.05 level for the National Ambulatory Medical Care Survey.

ices and hospital outpatient departments. Ratio of estimates is the ratio of the long form estimate to the short form estimate for the same characteristic.

Series 2, No. 139[ Page 19
tory care settings with standard error of percent by form length, ratio of estimates, selected diagnostic and screening services, and selected

hort form write-in responses and long form check boxes: Split-panel study, 2001

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Short form Long form Short form Long form Short form Long form Short form Long form

write-in check Ratio of write-in check Ratio of write-in check write-in check

responses boxes estimates responses boxes estimates responses boxes responses boxes

Percent of visits Percent of visits Standard error of percent

...... 3.1 7.6 2.5 1.8 5.0 2.8 0.5 1.5 0.3 0.8

...... 3.1 7.7 2.5 2.9 6.4 2.2 0.7 1.5 0.4 1.0

...... 1.6 4.4 2.8 0.6 3.3 5.5 0.3 0.8 0.1 0.6

...... 2.5 20.3 8.1 1.8 19.8 11.0 0.6 2.0 0.5 2.6

...... 3.8 22.9 6.1 *2.6 17.6 6.5 0.8 2.2 0.9 2.0

...... 0.7 18.8 27.3 *0.9 17.9 19.9 0.2 2.2 0.3 2.2

...... *0.2 9.4 46.9 *0.1 9.3 93.0 0.1 1.5 0.1 1.7

...... 0.7 10.6 15.6 *0.9 9.2 10.2 0.1 1.4 0.3 1.6

...... 0.4 *0.9 2.5 1.0 1.2 1.2 0.1 0.4 0.2 0.3

...... * 0.6 . . . * 0.7 . . . * 0.2 * 0.2

...... 1.0 1.4 1.3 0.9 1.8 2.0 0.2 0.3 0.2 0.4

...... 0.5 *2.1 4.1 0.7 2.3 3.3 0.1 0.8 0.2 0.5

...... * 3.4 . . . * 1.7 . . . * 0.5 * 0.3

...... * 3.9 . . . * 2.2 . . . * 0.6 * 0.4

...... 0.6 4.6 7.2 *0.3 3.7 12.3 0.3 0.6 0.1 0.5

...... * 1.8 . . . * 1.0 . . . * 0.4 * 0.2

...... * 8.5 . . . 0.7 8.5 12.1 * 0.9 0.2 1.3

...... * * . . . *0.2 0.9 4.5 * * 0.1 0.2

...... 1.1 1.5 1.4 1.0 1.6 1.6 0.2 0.4 0.2 0.2

...... 0.5 0.6 1.2 *0.3 *0.5 1.7 0.1 0.1 0.1 0.2

...... * * . . . * *1.1 . . . * * * 0.5

...... * 0.1 . . . *0.3 *0.3 1.0 * 0.0 0.2 0.1

...... *0.3 *0.4 1.3 *0.6 *0.7 1.2 0.2 0.2 0.2 0.2

...... *0.3 0.3 0.9 *0.1 *0.3 3.0 0.2 0.1 0.0 0.2

...... *0.5 4.9 9.8 0.3 1.4 4.7 0.2 0.9 0.1 0.4

...... * 2.5 . . . * *0.3 . . . * 0.6 * 0.2...... *0.3 0.6 1.8 *0.7 *0.5 0.7 0.1 0.1 0.2 0.2

...... * 0.2 . . . * * . . . * 0.1 * 0.2

...... 1.2 0.6 0.5 *1.3 *1.2 0.9 0.3 0.1 0.4 0.4

...... 1.2 *0.4 0.3 1.0 *0.4 0.4 0.3 0.2 0.2 0.2

...... 0.3 0.3 0.8 *0.1 *0.2 2.0 0.1 0.1 0.1 0.1

...... 92.1 92.8 1.0 93.4 94.3 1.0 0.6 0.7 0.9 0.8

...... 7.9 7.2 0.9 6.6 5.9 0.9 0.6 0.7 0.9 0.8

...... 1.1 1.4 1.3 0.9 *1.6 1.8 0.2 0.2 0.2 0.5

...... 2.3 2.7 1.2 1.4 1.5 1.1 0.3 0.4 0.3 0.3

...... 0.3 1.2 3.8 0.5 *0.4 0.8 0.1 0.3 0.1 0.1

Page 20[ Series 2, No. 139

eet standard of reliability or precision. 1Difference between short and long form percents is statistically significant at the α=0.05 level for the National Hospital Ambulatory Medical Care Survey (NHAMCS).

statistically significant at the α=0.05 level for both National Ambulatory Medical Care Survey (NAMCS) and NHAMCS.statistically significant at the α=0.05 level for the NAMCS.

entry, while the long form estimate indicates either a check box or write-in response was made.

ices and hospital outpatient departments. Ratio of estimates is the ratio of the long form estimate to the short form estimate for the same characteristic.
tory care settings with standard error of percent by form length, ratio of estimates, and counseling, education, or therapeutic services:

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Short Long Ratio of Short Long Ratio of Short Long Short Long

vided form form estimates form form estimates form form form form

Percent of visits Percent of visits Standard error of percent

........ 56.2 53.5 1.0 58.2 50.3 0.9 2.0 2.6 3.2 3.7

........ 39.9 43.4 1.1 39.3 47.9 1.2 2.0 2.5 3.1 3.7

........ 2.0 0.9 0.4 1.3 1.6 1.2 0.4 0.2 0.2 0.4

........ . . . 1.6 . . . . . . 1.3 . . . . . . 0.4 . . . 0.3

........ . . . 1.7 . . . . . . 1.8 . . . . . . 0.4 . . . 0.3

........ 13.7 9.9 0.7 13.7 8.7 0.6 1.1 1.4 1.9 1.1

........ . . . * . . . . . . 0.4 . . . . . . * . . . 0.1

........ . . . 0.6 . . . . . . 2.5 . . . . . . 0.1 . . . 0.8

........ 8.8 8.0 0.9 5.2 3.9 0.8 0.9 1.4 0.9 0.8

........ 3.7 3.8 1.0 3.8 3.0 0.8 0.6 0.9 0.8 0.6

........ . . . * . . . . . . 0.8 . . . . . . * . . . 0.2

........ . . . 1.8 . . . . . . 1.6 . . . . . . 0.4 . . . 0.3

........ 3.9 3.9 1.0 3.2 5.7 1.8 0.4 0.9 0.9 1.7

........ 2.5 1.7 0.7 1.7 2.0 1.2 0.4 0.3 0.2 0.3

........ 2.5 2.9 1.1 *1.5 1.7 1.1 0.4 0.4 0.6 0.3

........ 16.9 20.1 1.2 20.0 25.4 1.3 1.5 1.8 2.2 3.1

CAM)2 .... . . . * . . . . . . 0.1 . . . . . . * . . . 0.1

........ . . . 0.4 . . . . . . 0.2 . . . . . . 0.1 . . . 0.1

........ . . . *0.3 . . . . . . 0.4 . . . . . . 0.2 . . . 0.2

........ . . . *2.9 . . . . . . 2.3 . . . . . . 0.9 . . . 0.9

........ 2.3 0.7 0.3 1.0 1.1 1.1 0.4 0.2 0.2 0.6

........ 2.1 1.8 0.9 4.1 4.0 1.0 0.4 0.5 1.2 1.3

........ . . . 1.9 . . . . . . 2.6 . . . . . . 0.4 . . . 0.5

........ . . . 1.7 . . . . . . 2.2 . . . . . . 0.3 . . . 0.5

........ 3.9 3.1 0.8 2.6 1.8 0.7 0.7 0.7 0.7 0.4

cision.

s statistically significant at the α = 0.05 level for the National Ambulatory Medical Care Survey.

ices and hospital outpatient departments. Ratio of estimates is the ratio of the long form estimate to the short form estimate for the same characteristic.

Series 2, No. 139[ Page 21
tory care settings with standard error of percent by form length, ratio of estimates, and disposition: Split-panel study, 2001

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Short Long Ratio of Short Long Ratio of Short Long Short Long

form form estimates form form estimates form form form form

Percent of visits Percent of visits Standard error of percent

........ 100.0 100.0 . . . 100.0 100.0 . . . . . . . . . . . . . . .

........ 9.3 11.0 1.2 10.3 7.5 0.7 1.2 1.6 2.3 1.2

........ 24.8 24.7 1.0 23.3 29.2 1.3 1.4 1.6 2.1 3.8

........ 5.6 5.8 1.0 12.5 7.4 0.6 0.5 0.6 1.4 0.8

........ 61.7 59.7 1.0 57.8 59.8 1.0 1.7 2.0 3.0 3.9

........ 2.0 1.7 0.9 2.3 1.7 0.7 0.3 0.3 0.7 0.4

........ . . . 2.4 . . . . . . 2.8 . . . 0.4 . . . . . . 0.6

........ 0.4 0.3 0.8 0.7 0.5 0.7 0.1 0.1 0.1 0.1

2,3 ...... . . . 0.4 . . . . . . 0.4 . . . . . . 0.1 . . . 0.1

........ . . . * . . . . . . 0.2 . . . . . . * . . . 0.0

........ 1.6 1.7 1.1 3.1 1.2 0.4 0.3 0.5 0.7 0.2

........ 2.2 1.9 0.9 3.5 0.9 0.3 0.5 0.4 1.9 0.2

........ 97.8 98.1 1.0 96.5 99.1 1.0 0.5 0.4 1.9 0.2

cision.

s statistically significant at the α = 0.05 level for the National Ambulatory Medical Care Survey.

pist.

ices and hospital outpatient departments. Ratio of estimates is the ratio of the long form estimate to the short form estimate for the same characteristic.

Page 22[ Series 2, No. 139
atory care settings with standard error of percent by form length, ratio of estimates, and providers seen: Split-panel study, 2001

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Short Long Ratio of Short Long Ratio of Short Long Short Long

form form estimates form form estimates form form form form

Percent of visits Percent of visits Standard error of percent

........ 100.0 100.0 . . . 100.0 100.0 . . . . . . . . . . . . . . .

........ 96.7 95.8 1.0 77.6 80.1 1.0 0.7 0.8 4.2 2.9

........ . . . . . . . . . 65.9 74.4 1.1 . . . . . . 4.5 3.3

........ . . . . . . . . . 18.8 9.8 0.5 . . . . . . 2.7 1.8

........ . . . . . . . . . 3.9 3.9 1.0 . . . . . . 0.8 1.1

........ . . . . . . . . . . . . 0.8 . . . . . . . . . . . . 0.3

........ 16.9 24.7 1.5 38.6 37.1 1.0 2.5 3.0 4.2 5.0

........ 12.9 9.1 0.7 20.2 11.5 0.6 1.7 1.7 4.3 2.9

........ 25.3 16.9 0.7 12.1 13.6 1.1 2.7 2.5 3.1 3.4

........ 1.0 0.6 0.6 5.3 9.4 1.8 0.4 0.2 1.0 2.5

........ . . . 0.6 . . . . . . 9.1 . . . . . . 0.2 . . . 2.5

........ . . . * . . . . . . 0.2 . . . . . . * . . . 0.1

........ 2.9 3.1 1.1 6.7 6.4 1.0 1.6 0.9 2.8 1.8

........ 5.6 5.6 1.0 12.3 5.1 0.4 1.0 1 3.1 1.5

........ 3.3 3.3 1.0 8.4 6.8 0.8 1.0 0.6 1.3 1.5

........ 1.0 1.3 1.3 1.6 1.7 1.1 0.5 0.5 0.6 1.0

........ 99.0 98.7 1.0 98.4 98.3 1.0 0.5 0.5 0.6 1.0

cision.

s.

ices and hospital outpatient departments. Ratio of estimates is the ratio of the long form estimate to the short form estimate for the same characteristic.

Series 2, No. 139[ Page 23
its to ambulatory care settings and average number of medications with standard error of percent by form length, ratio of estimates,

medications: Split-panel study, 2001

Physician offices Hospital outpatient departments Physician offices Hospital outpatient departments

Short Long Ratio of Short Long Ratio of Short Long Short Long

form form estimates form form estimates form form form form

Percent distribution Percent distribution Standard error of percent

........ 100.0 100.0 . . . 100.0 100.0 . . . . . . . . . . . . . . .

........ 62.5 60.9 1.0 62.4 67.0 1.1 1.6 1.6 2.1 2.6

........ 37.5 39.1 1.0 37.6 33.0 0.9 1.6 1.6 2.1 2.6

Average Average Standard error of average

........ 2.4 2.4 1.0 2.3 2.4 1.0 0.1 0.1 0.0 0.1

escribed Percent distribution Percent distribution Standard error of percent

........ 100.0 100.0 . . . 100.0 100.0 . . . . . . . . . . . . . . .

........ 37.5 39.1 1.0 37.6 33.0 0.9 1.6 1.6 2.1 2.6

........ 25.9 24.8 1.0 23.7 24.3 1.0 0.9 0.9 1.2 1.3

........ 15.1 14.4 1.0 16.1 16.2 1.0 0.7 0.6 0.9 1.0

........ 8.6 7.7 0.9 8.5 9.7 1.1 0.7 0.5 0.5 1.0

........ 4.1 4.7 1.1 4.7 6.1 1.3 0.3 0.4 0.4 0.5........ 2.7 2.4 0.9 3.3 2.9 0.9 0.3 0.3 0.4 0.3........ 6.2 2.1 0.3 6.1 2.1 0.3 1.1 0.3 0.8 0.4

........ . . . 1.3 . . . . . . 1.8 . . . . . . 0.2 . . . 0.4........ . . . 3.4 . . . . . . 3.8 . . . . . . 0.6 . . . 0.8

........ 6.2 6.8 1.1 6.1 7.7 1.3 1.1 1.0 0.8 1.4

arations, immunizations, and desensitizing agents.

or prescribed.

the short form, but eight could be listed on the long form.

ices and hospital outpatient departments. Ratio of estimates is the ratio of the long form estimate to the short form estimate for the same characteristic. Numbers may not add to totals because of rounding.

Page 24[ Series 2, No. 139
Series 2, No. 139 [ Page 25

Table 12. Percent of visits to ambulatory care settings with standard error of percent by selected characteristics asked only on the long

form: Split-panel study, 2001

Physician offices Hospital outpatient departments

Percent Standard error Percent Standard error

Selected characteristic of visits of percent of visit of percent

Female .......................................... 100.0 . . . 100.0 . . .

Reported pregnant ................................... 5.4 1.1 8.1 1.1

Type of insurance plan

All types of plans:

HMO (staff model, e.g., Kaiser)1 ......................... 20.0 2.0 7.6 1.2

Other prepaid HMO (e.g., open model, IPA) .................. 10.8 1.4 6.1 1.2

Preferred provider organization .......................... 20.3 1.5 11.3 3.0

Point of service1 ................................... 4.4 0.7 1.5 0.5

Fee for service1 .................................... 10.6 1.2 4.1 1.1

Not insured1 ...................................... 2.3 0.3 7.7 1.6

Other1 .......................................... 15.2 1.5 31.1 4.0

Unknown or blank1 .................................. 16.4 2.0 30.7 3.4

All conditions:

Arthritis1 ........................................ 10.0 0.9 5.6 0.7

Asthma ......................................... 3.8 0.4 5.4 0.7

Depression ....................................... 7.1 0.8 9.6 1.7

Diabetes ........................................ 7.6 0.6 7.0 0.7

Hyperactivity/ADD .................................. 0.9 0.2 1.0 0.2

Hypertension ..................................... 17.7 1.0 14.8 1.3

Ischemic heart disease ............................... 4.3 0.4 2.9 0.6

Obesity ......................................... 6.7 0.7 5.4 0.7

None of the above .................................. 47.9 2.0 56.4 2.8

Visits with blood pressure taken:

Normal blood pressure reading2 .......................... 66.8 1.6 66.1 1.9

Above normal blood pressure reading3 ..................... 23.3 1.4 21.6 1.8

Below normal blood pressure reading1,4 ..................... 6.9 0.7 11.6 1.2

Unknown5 ....................................... 3.0 1.4 0.7 0.3

Drug visits6

:

Only new medications ................................ 37.4 2.5 39.6 4.0

Both old and new medications ........................... 14.6 1.0 15.7 1.4

Only old medications ................................ 39.0 2.1 34.1 4.1

Unknown ........................................ 9.0 1.3 10.6 2.3

Provider other than physician seen7

:

0 minutes ....................................... 26.3 3.1 . . . . . .

1–10 minutes ..................................... 49.5 3.1 . . . . . .

11–15 minutes .................................... 5.7 0.9 . . . . . .

16 minutes or more ................................. 4.3 0.6 . . . . . .

Blank .......................................... 14.2 1.9

. . . Category not applicable.

1Difference between physician office and hospital outpatient department percents is statistically significant at the α = 0.05 level.

2Normal blood pressure is defined as 100 – 140 mmHg systolic and 60 – 90 mmHg diastolic.

3High blood pressure is defined as either measurement above normal.

4Low blood pressure is defined as either measurement below normal.

5Unknown is defined as either or both systolic and diastolic measurements are missing.

6Visits at which one or more drugs were provided or prescribed.

7Check box for item collected only in physician offices.

NOTE: HMO is health maintenance organization, IPA is independent practice association, and ADD is attention deficit disorder.
Page 26 [ Series 2, No. 139

Appendix I. Patient Record Forms

Figure I. 2001 National Ambulatory Medical Care Survey Patient Record Form A
Series 2, No. 139 [ Page 27

Figure II. 2001 National Ambulatory Medical Care Survey Patient Record Form B (page 1 of 2)
Page 28 [ Series 2, No. 139

Figure II. 2001 National Ambulatory Medical Care Survey Patient Record Form B (page 2 of 2)
Series 2, No. 139 [ Page 29

Figure III. 2001 National Hospital Ambulatory Medical Care Survey Outpatient Department Patient Record Form A
Page 30 [ Series 2, No. 139

Figure IV. 2001 National Hospital Ambulatory Medical Care Survey Outpatient Department Patient Record Form B (page 1 of 2)
Series 2, No. 139 [ Page 31

Figure IV. 2001 National Hospital Ambulatory Medical Care Survey Outpatient Department Patient Record Form B (page 2 of 2)
Page 32 [ Series 2, No. 139

Appendix II

Definitions of Terms

Clinic—A clinic is an administrative

unit of the outpatient department where

ambulatory medical care is provided

under the supervision of a physician.

The following are examples of the types

of clinics included in the NHAMCS:

general medicine, surgery, pediatrics,

obstetrics and gynecology, substance

abuse, and others (e.g., psychiatry and

neurology). Clinics excluded from the

NHAMCS include ambulatory surgery

centers, chemotherapy, employee health

service, renal dialysis, methadone

maintenance, and radiology.

Drug mention—A drug mention is

the health care provider’s entry on the

Patient Record form of a pharmaceutical

agent—by any route of administration—

for prevention, diagnosis, or treatment.

Generic as well as brand name drugs are

included, as are nonprescription and

prescription drugs. Along with all new

drugs, the physician also records

continued medications if the patient was

specifically instructed during the visit to

continue the medication. Health care

providers could report up to six

medications per visit on the short form

and up to eight medications per visit on

the long form.

Drug visit—A drug visit is a visit at

which medication was prescribed or

provided by the physician.

Hospital—To be in scope for the

NHAMCS, a hospital must have an

average length of stay for all patients of

less than 30 days (short-stay) or be a

hospital whose specialty is general

(medical or surgical) or children’s

general, except Federal hospitals,

hospital units of institutions, and

hospitals with less than six beds staffed

for patient use.

Hospital size—Hospital size was

designated by the number of inpatient

beds in the hospital’s medical or

surgical units based on the SMG

Hospital Database.

In-scope physician—An in-scope

physician is a duly licensed doctor of

medicine (M.D.) or doctor of osteopathy

(D.O.) who is currently in office-based

practice and who spends some time

caring for ambulatory patients. Excluded

from NAMCS are physicians who are

hospital-based; who specialize in

anesthesiology, pathology, or radiology;

who are federally employed; who treat

only institutionalized patients; or who

are employed full-time by an institution

and spend no time seeing their own

ambulatory patients.

Office—An office is the space

identified by a physician as a location

for his or her ambulatory practice.

Offices customarily include consultation,

examination, or treatment spaces that

patients associate with the particular

physician.

Outpatient department—An

outpatient department is a hospital

facility where nonurgent ambulatory

medical care is provided under the

supervision of a physician.

Ownership—Hospitals are

designated according to the primary

owner of the hospital based on the SMG

Hospital Database.

Voluntary nonprofit—Hospitals that

are church-related or are a nonprofit

corporation or have other nonprofit

ownership.

Government, non-Federal—

Hospitals that are operated by State,

county, city, city-county, or hospital

district or authority.

Proprietary—Hospitals that are

individually owned or are

partnerships or corporations.

Patient—An ambulatory patient is

an individual seeking personal health

services who is not currently admitted to

any health care institution on the

premises.

Physician’s diagnosis—Up to three

diagnoses could be recorded. The

first-listed diagnosis should be the

physician’s or other health care

provider’s best assessment of a

diagnosis of the patient’s most important

problem, complaint, or symptom. In the

event of multiple diagnoses, the

physician was instructed to list them in

order of decreasing importance. The

term ‘‘primary’’ refers to the first-listed

diagnosis. The diagnosis represents the

provider’s best judgment at the time of

the visit and may be tentative,

provisional, or definitive. On the long

form only, physicians or other health

care staff were asked to list conditions

known to exist for the patient at this

time, regardless of their relationship to

the physician’s diagnoses.

Geographic region of residence—

The four geographic regions of the

United States that correspond to those

used by the U.S. Census Bureau are:

Region States included

Northeast Connecticut, Maine,

Massachusetts, New

Hampshire, New Jersey, New

York, Pennsylvania, Rhode

Island, and Vermont.

Midwest Illinois, Indiana, Iowa,

Kansas, Michigan,

Minnesota, Missouri,

Nebraska, North Dakota,

Ohio, South Dakota, and

Wisconsin.

South Alabama, Arkansas,

Delaware, District of

Columbia, Florida, Georgia,

Kentucky, Louisiana,

Maryland, Mississippi, North

Carolina, Oklahoma, South

Carolina, Tennessee, Texas,

Virginia, and West Virginia.

West Alaska, Arizona, California,

Colorado, Hawaii, Idaho,

Montana, Nevada, New

Mexico, Oregon, Utah,

Washington, and Wyoming.

Specialty hospital—A hospital was

considered a specialty hospital if the

primary type of care offered was not

‘‘general medical and surgical’’

according to the SMG Hospital

Database.

Teaching hospital—A hospital is

designated a teaching hospital if,

according to the SMG Hospital

Database, it is a member of the council

of teaching hospitals.

Visit—A visit is a direct, personal

exchange between an ambulatory patient

seeking care and a physician or a

hospital staff member working under the

physician’s supervision for the purpose

of rendering personal health services.

Excluded from the NAMCS and

NHAMCS are visits where medical care

was not provided, such as visits made to

drop off specimens, pay bills, and make

appointments.
Vital and Health Statistics

series descriptions

SERIES 1. Programs and Collection Procedures—These reports

describe the data collection programs of the National Center

for Health Statistics. They include descriptions of the methods

used to collect and process the data, definitions, and other

material necessary for understanding the data.

SERIES 2. Data Evaluation and Methods Research—These reports

are studies of new statistical methods and include analytical

techniques, objective evaluations of reliability of collected

data, and contributions to statistical theory. These studies

also include experimental tests of new survey methods and

comparisons of U.S. methodology with those of other

countries.

SERIES 3. Analytical and Epidemiological Studies—These reports

present analytical or interpretive studies based on vital and

health statistics. These reports carry the analyses further than

the expository types of reports in the other series.

SERIES 4. Documents and Committee Reports—These are final

reports of major committees concerned with vital and health

statistics and documents such as recommended model vital

registration laws and revised birth and death certificates.

SERIES 5. International Vital and Health Statistics Reports—These

reports are analytical or descriptive reports that compare U.S.

vital and health statistics with those of other countries or

present other international data of relevance to the health

statistics system of the United States.

SERIES 6. Cognition and Survey Measurement—These reports are

from the National Laboratory for Collaborative Research in

Cognition and Survey Measurement. They use methods of

cognitive science to design, evaluate, and test survey

instruments.

SERIES 10. Data From the National Health Interview Survey—These

reports contain statistics on illness; unintentional injuries;

disability; use of hospital, medical, and other health services;

and a wide range of special current health topics covering

many aspects of health behaviors, health status, and health

care utilization. They are based on data collected in a

continuing national household interview survey.

SERIES 11. Data From the National Health Examination Survey, the

National Health and Nutrition Examination Surveys, and

the Hispanic Health and Nutrition Examination Survey—

Data from direct examination, testing, and measurement on

representative samples of the civilian noninstitutionalized

population provide the basis for (1) medically defined total

prevalence of specific diseases or conditions in the United

States and the distributions of the population with respect to

physical, physiological, and psychological characteristics, and

(2) analyses of trends and relationships among various

measurements and between survey periods.

SERIES 12. Data From the Institutionalized Population Surveys—

Discontinued in 1975. Reports from these surveys are

included in Series 13.

SERIES 13. Data From the National Health Care Survey—These

reports contain statistics on health resources and the public’s

use of health care resources including ambulatory, hospital,

and long-term care services based on data collected directly

from health care providers and provider records.

SERIES 14. Data on Health Resources: Manpower and Facilities—

Discontinued in 1990. Reports on the numbers, geographic

distribution, and characteristics of health resources are now

included in Series 13.

SERIES 15. Data From Special Surveys—These reports contain

statistics on health and health-related topics collected in

special surveys that are not part of the continuing data

systems of the National Center for Health Statistics.

SERIES 16. Compilations of Advance Data From Vital and Health

Statistics—Advance Data Reports provide early release of

information from the National Center for Health Statistics’

health and demographic surveys. They are compiled in the

order in which they are published. Some of these releases

may be followed by detailed reports in Series 10–13.

SERIES 20. Data on Mortality—These reports contain statistics on

mortality that are not included in regular, annual, or monthly

reports. Special analyses by cause of death, age, other

demographic variables, and geographic and trend analyses

are included.

SERIES 21. Data on Natality, Marriage, and Divorce—These reports

contain statistics on natality, marriage, and divorce that are

not included in regular, annual, or monthly reports. Special

analyses by health and demographic variables and

geographic and trend analyses are included.

SERIES 22. Data From the National Mortality and Natality Surveys—

Discontinued in 1975. Reports from these sample surveys,

based on vital records, are now published in Series 20 or 21.

SERIES 23. Data From the National Survey of Family Growth—These

reports contain statistics on factors that affect birth rates,

including contraception, infertility, cohabitation, marriage,

divorce, and remarriage; adoption; use of medical care for

family planning and infertility; and related maternal and infant

health topics. These statistics are based on national surveys

of women of childbearing age.

SERIES 24. Compilations of Data on Natality, Mortality, Marriage, and

Divorce—These include advance reports of births, deaths,

marriages, and divorces based on final data from the National

Vital Statistics System that were published as National Vital

Statistics Reports (NVSR), formerly Monthly Vital Statistics

Report. These reports provide highlights and summaries of

detailed data subsequently published in Vital Statistics of the

United States. Other special reports published here provide

selected findings based on final data from the National Vital

Statistics System and may be followed by detailed reports in

Series 20 or 21.

For answers to questions about this report or for a list of reports published

in these series, contact:

Information Dissemination Staff

National Center for Health Statistics

Centers for Disease Control and Prevention

3311 Toledo Road, Room 5412

Hyattsville, MD 20782

1-866-441-NCHS (6247)

E-mail: nchsquery@cdc.gov

Internet: www.cdc.gov/nchs
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DHHS Publication No. (PHS) 2005-1339, Series 2, No. 139

05-0127 (6/2005)