Nonresponse Bias in
 

Estimates From the 2012
 

National Ambulatory
 

Medical Care Survey
 

Series 2, Number 171 February 2016
Copyright information

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reproduced or copied without permission; citation as to source, however, is

appreciated.

Suggested citation

Hing E, Shimizu IM, Talwalkar A. Nonresponse bias in estimates from the 2012

National Ambulatory Medical Care Survey. National Center for Health Statistics.

Vital Health Stat 2(171). 2016.

Library of Congress Cataloging-in-Publication Data

Names: National Center for Health Statistics (U.S.), issuing body.

Title: Nonresponse bias in estimates from the 2012 National Ambulatory

Medical Care Survey.

Other titles: Vital and health statistics. Series 2, Data evaluation and

methods research ; no. 171. | DHHS publication ; no. 2016–1371. 0276–4733

Description: Hyattsville, Maryland : U.S. Department of Health and Human

Services, Centers for Disease Control and Prevention, National Center for

Health Statistics, 2016. | Series: Vital and health statistics, series 2,

data evaluation and methods research ; number 171 | Series: DHHS

publication ; no. (PHS) 2016–1371 | Includes bibliographical references

and index.

Identifiers: LCCN 2015045700 | ISBN 0840606745 (alk. paper) |

ISBN 9780840606747 (alk. paper)

Subjects: | MESH: National Ambulatory Medical Care Survey (U.S.) | Health

Care Surveys—United States. | Ambulatory Care—statistics & numerical

data—United States. | Health Records, Personal—United States. |

Interviews as Topic—United States. | Sampling Studies—United States.

Classification: LCC RA974 | NLM W2 A N148vb no.171 2015 | DDC

362.12072/7—dc23

LC record available at http://lccn.loc.gov/2015045700

For sale by the U.S. Government Printing Office

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Washington, DC 20402–9328

Printed on acid-free paper.
Series 2, Number 171

Nonresponse Bias in Estimates

From the 2012 National Ambulatory

Medical Care Survey

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

February 2016

DHHS Publication No. 2016–1371
National Center for Health Statistics

Charles J. Rothwell, M.S., M.B.A., Director

Nathaniel Schenker, Ph.D., Deputy Director

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

Division of Health Care Statistics

Clarice Brown, M.S., Director

Alexander Strashny, Ph.D., Associate Director for Science
Contents
 

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

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

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

2012 Sampling Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
 

Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
 

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
 

Response Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
 

Bias Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
 

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
 

Response to Induction Interview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
 

Response to Patient Record Forms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
 

Nonresponse Bias Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
 

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
 

Limitations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
 

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
 

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
 

Appendix I. Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
 

Appendix II. NAMCS Estimation Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
 

Appendix III. Physicians With Full or Adequate Response to Patient Record Forms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
 

Text Figure

Survey participation, full Patient Record Form response, and Patient Record Form completion rates: National
 

Ambulatory Medical Care Survey, 2002–2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
 

Text Table

Percentage of in-scope sample physicians, by type of physician response to Patient Record Form: National
 

Ambulatory Medical Care Survey, 2010–2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
 

Detailed Tables

1.	 In-scope sample physicians and their weighted percent distributions and rates of response to the physician induction
 

interview, by physician characteristics: National Ambulatory Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . 12
 

2.	 In-scope sample physicians and their weighted percent distributions and rates of response to the physician induction
 

interview, by division and state where interview occurred: National Ambulatory Medical Care Survey, 2012 . . . . . . . . . 14
 

3.	 In-scope sample physicians, their weighted percent distributions by Patient Record Form status, and Patient Record
 

Form completion rate, by physician characteristics: National Ambulatory Medical Care Survey, 2012 . . . . . . . . . . . . . . 16
 

iii
4.	 In-scope sample physicians, their weighted percent distributions by Patient Record Form status, and Patient Record
 

Form completion rate, by state location of office where the most visits were seen: National Ambulatory Medical Care
 

Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
 

5.	 Patient Record Forms expected and completed, their weighted percent distributions, and percentage of expected
 

Patient Record Forms completed, by physician characteristics: National Ambulatory Medical Care Survey, 2012 . . . . . 20
 

6.	 Patient Record Forms expected and completed, their weighted percent distributions, and percentage of expected
 

Patient Record Forms completed, by state location of office where the most visits were seen: National Ambulatory
 

Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
 

7.	 Percent distributions of in-scope sample, numbers of respondents to physician induction interview, and potential bias
 

in nonresponse-adjusted estimates of percent distributions based on those respondents, by physician characteristic:
 

National Ambulatory Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
 

8.	 Percent distribution of in-scope sample, numbers of respondents to physician induction interview, and potential bias
 

in nonresponse-adjusted estimates of percent distributions based on those respondents, by state location where
 

induction interview occurred: National Ambulatory Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
 

9.	 Percent distributions of in-scope sample, numbers of physicians completing Patient Record Forms, and potential bias
 

in nonresponse-adjusted estimates of percent distributions based on Patient Record Form completers, by physician
 

characteristics: National Ambulatory Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
 

10.	 Percent distribution of in-scope sample, numbers of physicians completing Patient Record Forms, and potential bias
 

in nonresponse-adjusted estimates of percent distributions based on Patient Record Form completers, by state location
 

of office where the most visits were seen: National Ambulatory Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . 30
 

11.	 Estimated percentages of physicians, by selected physician characteristics from the National Electronic Health Record
 

Survey and the National Ambulatory Medical Care Survey: 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
 

12.	 Percent distributions of visits based on in-scope physician sample, numbers of sampled visits, and potential bias in
 

nonresponse-adjusted estimates of percent distributions of visits, by physician characteristics: National Ambulatory
 

Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
 

13.	 Percent distributions of visits based on in-scope physician sample, numbers of sampled visits, and potential bias in
 

nonresponse-adjusted estimates of percent distributions of visits, by state location of office where the most visits were
 

seen: National Ambulatory Medical Care Survey, 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
 

Appendix Tables

I.	 In-scope sample physicians, their weighted percent distributions by Patient Record Form response status, and Patient
 

Record Form response rate, by physician characteristics: National Ambulatory Medical Care Survey, 2012. . . . . . . . . . . 39
 

II.	 In-scope sample physicians, their weighted percent distributions by Patient Record Form response status, and
 

Patient Record Form response rate, by state location of office where the most visits were seen: National Ambulatory
 

Medical Care Survey, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
 

iv
Background

The National Ambulatory Medical

Care Survey (NAMCS) is an annual,

nationally representative sample survey

of physicians and of visits to physicians.

Two major changes were made to the

2012 NAMCS to support reliable state

estimates. The sampling design

changed from an area sample to a

fivefold-larger list sample of physicians

stratified by the nine U.S. Census Bureau

divisions and 34 states. At the same time,

the data collection mode changed from

paper forms to laptop-assisted data

collection and from physician or office

staff abstraction of medical records to

predominantly Census interviewer

abstraction using automated Patient

Record Forms (PRFs).

Objectives

This report presents an analysis of

potential nonresponse bias in 2012

NAMCS estimates of physicians and

visits to physicians. This analysis used

two sets of physician-based estimates:

one measuring the completion of the

physician induction interview and

another based on completing any PRF.

Evaluation of visit response was

measured by the percentage of

expected PRFs completed. For each

type of physician estimate, response

was evaluated by (a) comparing percent

distributions of respondents and

nonrespondents by physician

characteristics available for all in-scope

sample physicians, (b) comparing

response rates by physician

characteristics with the national response

rate, and (c) analyzing nonresponse bias

after adjustments for nonresponse were

applied in survey weights. For visit

estimates, response was evaluated by

(a) comparing the percent distributions of

expected visits and completed visits,

(b) comparing visit response rates by

physician characteristics with the national

visit response rate, and (c) analyzing

visit-level nonresponse bias after

adjustments for nonresponse were

applied in visit survey weights. Finally,

potential bias in the two physician-level

estimates was computed by comparing

them with those from an external survey.

Keywords: Response rate •

evaluation • NAMCS

Nonresponse Bias in Estimates

From the 2012 National

Ambulatory Medical Care Survey

by Esther Hing, M.P.H.; Iris M. Shimizu, Ph.D.; and

Anjali Talwalkar, M.D., M.P.H.

Introduction

The National Ambulatory Medical

Care Survey (NAMCS) began in 1973

as a nationally representative sample

survey of nonfederal office-based

physicians (excluding anesthesiologists,

pathologists, and radiologists) and their

patient visits. It has been conducted

annually (except during 1982–1984 and

1986–1988) by the Centers for Disease

Control and Prevention’s (CDC)

National Center for Health Statistics

(NCHS). Sample physicians are selected

from lists obtained from the American

Medical Association (AMA) and the

American Osteopathic Association

(AOA). Starting in 2006, the survey was

expanded to include samples of

providers in community health centers

and their patient visits. However,

analysis in this report is limited to

potential bias in the 2012 base NAMCS

alone; that is, the 2012 NAMCS survey

of community health centers and their

providers is excluded from this

study (1). Thus, for convenience, in the

remainder of this report the term

NAMCS refers to the base NAMCS

unless otherwise stated. Prior to 2012,

the expanded NAMCS (with community

health centers) used a multistage

probability sampling design involving

samples of geographic primary sampling

units (PSUs), physicians and community

health centers within PSUs, and visits to

sampled providers. The sample size

permitted national and regional

estimates but did not support reliable

estimates by state.

The 2012 expanded NAMCS

underwent two major changes, either of

which might have a negative impact on

response rates. First, additional funding

for the 2012 NAMCS permitted the

sample size to be increased sufficiently

to produce estimates for each of the

U.S. Census Bureau divisions and the

34 most populous states. For this

purpose, a list sample of physicians was

used instead of an area sample. The

other major change for 2012 was the

mode of data collection. Prior to 2012,

data were collected using paper

questionnaires. Interviewers collected

physician data through in-person

interviews. Visit data were extracted by

physicians or their staff as the preferred

mode of collection, but interviewer

abstraction from medical records had

been increasing over time. In 2012,

laptop-assisted data collection using

automated survey instruments was

initiated, with medical abstraction by

interviewers as the predominant method

of data collection.

In this report, the potential for

nonresponse bias is evaluated for two

types of NAMCS estimates: physician

estimates and visit estimates. Physician

estimates were evaluated in two ways:

response to the physician induction

interview (i.e., the collection of

physician-level characteristics) and the

receipt of at least one Patient Record

Form (PRF) from that physician. Visit

estimates were evaluated by comparing

the number of visit records received

with the number expected. Nonresponse

bias for physician completion of the

induction interview, for physician

completion of at least one visit record,

and for visits from the 2012 base

NAMCS was evaluated by comparing

response rates and distributions of

Page 1
Page 2 [ Series 2, No. 171

responding and nonresponding units by

physician characteristics available for all

in-scope sample physicians reported in

master files of the AMA and AOA and

updated during the survey. In addition to

the AMA and AOA information,

quartiles of annual visit volume were

examined at the two levels of response

for visit estimates because research

found that physician response to PRFs

was associated with annual visit

volume (2). Items needed to estimate

annual visit volume were collected in

the induction interview for all in-scope

physicians. Changes from prior years in

physician visit-level response to the PRF

were also explored by comparing

NAMCS PRF response levels in 2010

through 2012.

Evaluation of potential nonresponse

bias was conducted for physician

estimates based on physicians

completing the induction interview and

on physicians completing any PRF. For

these two sets of physician estimates,

bias is defined as the difference between

the estimated percentages based on the

full in-scope sample of physicians and

the estimated percentages based on

survey respondents using sample weights

adjusted for nonresponse. Potential

biases in physician-level estimates were

also examined by comparing NAMCS

estimates with an external data

source—the 2012 National Electronic

Health Records Survey (NEHRS)—a

survey similar in scope and timing to

NAMCS (3). Potential visit-level bias

was examined by comparing the

estimated percentages of visits based on

completed PRFs using sample weights

adjusted for nonresponse and the

estimated percentages of visits based on

the full in-scope physician sample.

Background

2012 Sampling Design

From its inception, NAMCS has

constructed its physician sampling frame

from lists of physicians classified as

office-based and nonfederally employed

in the master files of the AMA and

AOA. For 2012, four mutually exclusive

stratified samples of physicians were

selected: a core sample and three

supplemental samples. For the core

sample, strata were defined by practice

type (primary care or nonprimary care)

and by the nine Census divisions and

the 34 most populous states. In 2012,

the 34 most populous states (in

descending order) were California,

Texas, New York, Florida, Illinois,

Pennsylvania, Ohio, Michigan, New

Jersey, Georgia, North Carolina,

Virginia, Washington, Massachusetts,

Indiana, Arizona, Tennessee, Missouri,

Maryland, Wisconsin, Minnesota,

Colorado, Alabama, South Carolina,

Louisiana, Kentucky, Oregon,

Oklahoma, Connecticut, Iowa,

Mississippi, Arkansas, Kansas, and

Utah. The core sample consisted 14,590

physicians. Three supplemental national

samples consisting of 1,150 physicians

(total) within the specialties of oncology,

allergy, and pulmonology were selected

to permit separate estimation for these

groups. Each supplemental sample was

stratified by Census division. Overall,

15,740 physicians were selected for the

2012 NAMCS sample. At the final

sampling stage, patient visits were

sampled within physicians’ practices.

For this stage, physicians were randomly

assigned to one of 52 reporting weeks

throughout the year. A systematic

random sample of visits was selected from

those made to the physician’s practice

during the assigned reporting week.

Data Collection

The U.S. Census Bureau served as

the data collection agent for the 2012

NAMCS. Data regarding the physician’s

practice were collected by Census

interviewers (also referred to in this

report as field representatives or FRs)

through an in-person interview; data on

sample visits were abstracted from the

physician’s medical records. In 2012,

NAMCS switched from its traditional

paper-and-pencil mode of data collection

to an automated survey tool at both the

physician and visit levels. Consequently,

most of the data collection and data

processing systems developed over the

years had to be redesigned. This

included revised wording, answer

choices, skip patterns, and range checks.

Numerous help screens were created to

provide FRs additional information to

aid the visit data abstraction. Hard and

soft edits were also incorporated into the

automated tool. Soft edits prompted

field staff to double-check a

questionable entry but allowed them to

proceed if the entry was thought to be

correct, whereas hard edits resulted in

strict range restrictions.

Physician induction interview

Survey questions about physician

eligibility and physician and practice

characteristics, previously collected

using a physician induction interview

paper form, were incorporated in the

automated survey tool and collected by

FRs. The induction interview was used

to screen sample physicians to ensure

they were eligible for NAMCS. Eligible

physicians included nonfederally

employed physicians providing direct

patient care in office-based settings;

anesthesiologists, pathologists, and

radiologists were excluded. Information

sufficient to determine eligibility status

was obtained for every sampled

physician, regardless of whether the

physician agreed to complete the

induction interview. A total of 6,166

sample physicians were ineligible for

the study. The most frequent reasons for

being ineligible or ‘‘out-of-scope’’ were

that the physician either was retired or

was employed in a hospital emergency

department, outpatient department, or

institutional setting.

For eligible physicians, information

about the physician and his or her

practice, as well as contacts for

collecting visit data, were also obtained

in the induction interview. Of the 9,574

in-scope (eligible) sample physicians,

5,622 met the criteria for being

considered respondents to the physician

induction interview, for an unweighted

response rate of 58.7% (59.7% weighted)

(Table 1). To be considered a respondent

to the induction interview, eligible

physicians were required to:

+	 Report characteristics of at least one

practice office, including numbers of

physicians and specialties,

ownership, staffing, capabilities for

selected medical tests, and evening

and weekend hours.
Series 2, No. 171 [ Page 3

+	 Report whether the practice uses any

electronic health record (EHR) or

electronic medical record (EMR)

systems and, if the response was yes,

answer at least 9 of the following

17 questions about the capabilities

and use of those systems:

C Recording patient history and

demographic information?

C Recording and charting vital

signs?

C Recording patient smoking status?

C Recording clinical notes?

C Ordering prescriptions?

C Providing reminders for

guideline-based interventions or

screening tests?

C	 Providing standard order sets

related to a particular condition or

procedure?

C Ordering laboratory tests?
 

C Viewing laboratory results?
 

C Viewing imaging results?
 

C Viewing data on quality-of-care
 

measures?

C	 Reporting clinical quality

measures to federal or state

agencies (such as the Centers for

Medicare & Medicaid Services

[CMS] or Medicaid)?

C Generating lists of patients with

particular health conditions?

C Reporting electronically to

immunization registries?

C Providing patients with clinical

summaries for each visit?

C Exchanging secure messages with

patients?

C	 Providing patients with an

electronic copy of their health

information?

Patient Record Form

In past years, data collection of visit

information was expected to be carried

out by the physician or the physician’s

staff using a paper questionnaire, the

Patient Record Form or PRF. Over time,

abstraction from medical charts by

Census FRs became the predominant

mode (55% of PRF data were abstracted

by FRs in 2010). For 2012, Census FR

abstraction using laptop computers and

the automated instrument became the

preferred mode for data collection. For

physicians who preferred to do their

own data abstraction, a Web portal

containing a modified version of the

automated tool was available, or a

Census laptop was left behind for

physician use. In 2012, 98% of records

were obtained through Census FR

abstraction and 2% were obtained by

physician or medical staff abstraction.

For visit sampling, physicians were

instructed to keep a daily listing of all

patient visits during the assigned

reporting week by using an arrival log,

optional worksheet, or similar method.

The list was to include both scheduled

and unscheduled patients; cancellations

and no-shows were excluded. Visits

were selected from the list by either

Census FRs or medical staff using a

random start and a sampling interval

that was determined based on the

physician’s estimated visits for the week

and the number of days the physician

was expected to see patients that week.

In this way, a systematic random sample

of visits was obtained. The sampling

procedures were designed so that about

30 visits would on average be selected

from the assigned reporting week. This

controlled the data collection workload

and maintained about equal reporting

levels among sample physicians,

regardless of visit volume. Sampled

visits were to be selected at all offices

where the physician saw patients in

the sample week. During data

processing, sampled visits were

assigned to the office location where

the visit occurred.

Data for sampled visits were

recorded on laptops using the automated

survey tool, which emulated the

traditional PRF survey instrument.

The 2012 Patient Record Sample Card

presenting data items included in

the survey is available from the

Ambulatory Health Care Data website at

http://www.cdc.gov/nchs/ahcd/

ahcd_survey_instruments.htm#namcs.

In this report, ‘‘PRF completers’’

are physicians with any completed PRFs

(or more precisely, physicians for whom

PRFs were completed by Census FRs or

by the physician and office staff; the

same distinction applies throughout the

rest of the report, but response is

characterized in terms of physicians for

convenience). For analysis of potential

bias in this report, the PRF completion

rate (percentage of in-scope sample

physicians who were PRF completers) is

examined because the PRF-completing

physicians are the only ones with

records in the visit-level file.

Methods

In this study, two sets of

physician-level response rates are

examined: response to induction

interview questions and response to any

PRF. The second set is examined

because visit-level files only include

records for physicians who completed

any PRF. In addition to examining

response for the physician-level

estimates, response rates for visit-level

estimates (as measured by the

percentage of expected PRFs that were

completed) were also examined. Data

analyses were performed using the

statistical packages SAS, version 9.3

(SAS Institute, Cary, N.C.) and

SUDAAN, version 11.0 (RTI

International, Research Triangle Park,

N.C.). Statements of differences in

estimates were tested for significance at

the p < 0.05 level. Differences by

selected physician characteristics were

examined using t tests for differences in

rates, and chi-square tests were used for

differences in percent distributions.

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.

Response Analysis

Similar methods are used to

evaluate response for both sets of the

physician-level estimates (induction

interview and physicians with completed

PRFs) and for visit-level estimates (4,5).

First, response rates and differences

between responders and nonresponders

in percent distributions are compared by

subgroups defined by physician

characteristics obtained from AMA and

AOA and updated during data

collection. Subgroups used in these

comparisons include physician age
Page 4 [ Series 2, No. 171

category (under age 50, aged 50 and

over), sex, type of doctor (Doctor of

Medicine [M.D.] or Doctor of

Osteopathy [D.O.]), physician specialty

(General or family practice, Internal

medicine, Pediatrics, General surgery,

Obstetrics and gynecology, Orthopedic

surgery, Cardiovascular diseases,

Dermatology, Urology, Psychiatry,

Neurology, Ophthalmology,

Otolaryngology, Oncology, Allergy,

Pulmonology, and a residual category of

Other specialties), specialty type

(Primary care, Surgical, and Medical),

practice type (Solo, Partner, Group or

health maintenance organization [HMO],

Medical school or government, Other,

and Unclassified), and location:

metropolitan statistical area (MSA)

status (MSA or non-MSA), Census

division (New England, Middle Atlantic,

East North Central, West North Central,

South Atlantic, East South Central, West

South Central, Mountain, Pacific), and

the 34 targeted states.

In addition to the previously listed

physician characteristics, quartiles of

annual visit volume were used to

compare percent distributions of total

sampled in-scope physicians and those

completing any PRF (see Appendix I for

details). Starting in 2003, a nonresponse

adjustment factor taking into account

annual visit volume has been included

in NAMCS weighting procedures for

visits because research has shown that

physician response to PRFs is associated

with annual visit volume (2). Annual

visit volumes are estimated as the

products of the numbers of weeks

physicians see patients and the numbers

of visits seen during normal practice

weeks, both of which are collected

during the induction interview for all

in-scope physicians.

For comparisons between

responders and nonresponders, estimates

were weighted by calibrated sampling

weights, which are the inverses of

sampling probabilities multiplied by

ratios that adjust the numbers of

physicians in the sampling frame at the

time of sample selection to the numbers

of physicians eligible for inclusion in

the sampling frame at the time of data

collection. Associations between

distributions of physician characteristics

by response status were assessed using

the chi-square test of association.

Response rate differences from the

overall response rate were also assessed.

For analysis of response in

visit-level statistics, no external data

source is available for comparison with

NAMCS visit estimates. Other than

characteristics of the physicians who

saw the patients for sampled visits, no

information is available about the

sample visits for which PRFs are

missing (i.e., nonrespondent sample

visits). Hence, to examine the potential

for nonresponse bias in visit-level

statistics, differences in numbers and

percent distributions between expected

and completed PRFs are examined by

physician characteristics. No PRFs were

expected from 750 sampled physicians

who saw no patients during their

assigned reporting week. For the

remaining physicians, the number of

sample visits, and hence PRFs, for those

visits expected from each sampled

physician was estimated by dividing the

total visits the physician saw during his

or her assigned reporting week by the

sampling interval, determined during the

induction interview on the basis of visits

expected and days the physician

expected to see patients during the

reporting week.

Because values for visit counts or

sampling intervals were not always

reported in the induction interview,

especially for most of the

nonrespondents to the induction

interview, the following alternative

methods were used to estimate expected

numbers of sampled visits:

+	 For cases when the sampling interval

was missing from the induction

interview, the expected number of

sample visits for a physician was

estimated to be the minimum of 24

or the number of visits seen during

the physician’s reporting week. In

prior years, the average number of

PRFs sampled from each physician

with any PRF was 24 using the same

visit sampling instructions as used in

the 2012 NAMCS.

+	 For cases when the number of visits

seen in the reporting week was

unknown, that number was replaced

with the known or imputed number

of visits the physician saw during the

last normal week of practice.

Imputation was done by linear

regression using visit numbers

reported by similar physicians, where

similar is in terms of physician

specialty, Census division, MSA

status, physician age and race, and

reported practice size (see Appendix I

for details).

The total of expected sample visits

approximates the potential size of the

total visit sample had visits been

sampled correctly from every in-scope

sample physician who saw visits (or saw

patients) in the reporting week,

regardless of the physician’s response to

either the induction interview or PRFs.

The imputed number of visits during the

last normal practice week was used in

this estimate because the amount of

missing data was large and the imputed

number of visits seen during the last

normal week of practice was also used

in final visit estimation procedures.

Research conducted prior to finalizing

the weighting procedures showed that if

the mean of reported visits (used in

prior year estimates) had been used

instead of using regression methods to

impute the missing numbers of visits

seen in the physician’s last normal

practice week, the final estimate of total

visits would have understated visit

estimates compared with those for prior

years.

Note that the evaluation of visit

response bias is highly dependent on the

adequacy of the imputation methods

used. Although the most reasonable

imputation methods were applied, it is

possible that imputation results may

differ from true values. If this happened,

the estimated visit response rate and

bias will be inaccurate.

Bias Analysis

For the second evaluation method,

comparisons are made between percent

distributions. In each comparison, one of

the percent distributions is estimated

only on the basis of survey respondents,

using survey weights that are adjusted to

correct for nonresponse, while the other

distribution is estimated on the basis of

the total in-scope sample using only

calibrated sampling weights. Membership
Series 2, No. 171 [ Page 5

in the total in-scope sample was

determined for every sampled

physician, regardless of the physician’s

response status. See Appendix II for

details about the nonresponse-adjusted

survey weights.

Bias analysis in physician-level

estimates

Biases in the two sets of

physician-level estimates are computed

as the differences between estimates

based on the full in-scope sample and

estimates based on (a) only the

physicians completing the induction

interview and (b) only the physicians

completing any PRFs. Bias estimates at

the physician level were also derived by

comparing both sets of NAMCS

physician-level estimates with

comparable estimates from a separate

nationally representative physician

survey: the 2012 NEHRS. NAMCS

estimates are compared with NEHRS

estimates because the two surveys are

identical in scope and share the same

sampling frame source (physicians

classified as being in nonfederal

office-based practices in the master files

of AMA and AOA). The NEHRS mode

of data collection, however, differs from

that of NAMCS. NEHRS is conducted

by mail, whereas the 2012 NAMCS was

conducted by computer-assisted personal

interview. The unweighted response rate

for the 2012 NEHRS was 67% (65%

weighted) (6). Bias estimates were

derived as the differences between the

corresponding physician-level estimates

between the two surveys.

It is possible, but unknown, whether

mode or respondent type affected

differences in estimates from the 2012

NEHRS and 2012 NAMCS. A previous

study comparing 2008 EHR mail survey

estimates with NAMCS found no

differences in rates of missing data for

practice size, employee or ownership of

practice, and whether the practice was a

multispecialty practice. Respondent

effects are possible, however, because a

majority of NEHRS respondents were

the sampled physician, while a majority

of NAMCS induction interview

respondents were office staff (7,8).

In addition, both studies compared mail

survey data with NAMCS data collected

during personal interview using a paper

form.

Bias analysis in visit-level

estimates

To assess the potential for bias in

visit-level estimates due to PRF

nonresponse for sampled visits, two sets

of estimated percent distributions for

annual numbers of office-based visits by

physician characteristics are presented.

One set is based on the estimated annual

visit volumes (see Appendix I for

definition) for the total in-scope

physician sample weighted with the

physician-calibrated sampling weights

only. The other set is based on the

completed PRFs using nonresponseadjusted weights (see Appendix II for

details). Because nonresponse

adjustments at the national level differ

from those at the state level, there are

two visit-level weights. Weights

designed for national visit estimates

were used in estimating percent

distributions by physician characteristics

other than by state, while weights for

state estimates were used to estimate

percent distributions of visits by the 34

targeted states.

Results

Response to Induction

Interview

Information on response to the

induction interview was examined by

comparing percent distributions of

responders and nonresponders by

physician characteristics (Tables 1

and 2). The overall weighted response

rate to the induction interview was

59.7% (Table 1). Distributions of

responders and nonresponders did not

vary by physician age, sex, type of

doctor (M.D. or D.O.), or practice type.

However, distributions did vary between

respondents and nonrespondents by

physician specialty, specialty type,

Census division (Table 1), and selected

states (Table 2). Compared with the

national average, the response rate was

lower among physicians in New

England (51.3%) and higher in the East

North Central Division (65.1%) and the

East South Central Division (64.1%).

Again, compared with the national

average, response rates were higher

among general or family practitioners

(64.3%) and pediatricians (70.0%), but

were lower among orthopedic surgeons

(53.9%), specialists in cardiovascular

diseases (51.2%), and oncologists

(51.4%). Compared with the national

average, physicians in primary care

specialties responded more frequently

(62.4%), while those in surgical

specialties responded less frequently

(54.9%). The response rate for

physicians in solo practice (63.2%) was

significantly higher than the national

average (Table 1).

The induction interview response

rate varied widely among the 34 most

populous states (Table 2). Compared

with the national average, response rates

were higher among physicians in eight

states (Illinois, Indiana, Wisconsin,

Virginia, Alabama, Tennessee,

Oklahoma, and Utah) and were lower

than the national rate in five states

(Minnesota, North Carolina, South

Carolina, Mississippi, and Louisiana).

Response to Patient Record

Forms

Response for physician-level

estimates

The first level of response for

completing PRFs is at the physician

level. Of the 9,574 in-scope (eligible)

physicians, 37.4% unweighted (38.4%,

weighted) or 3,583 physicians completed

any PRF. This is 63.7% unweighted

(64.3% weighted) of the in-scope

physicians who completed the induction

interview. Table 3 gives percent

distributions of physicians by PRF

completion status and physician

characteristics. Overall, a statistically

significant association was seen between

distributions of physicians by PRF

completion status and Census division

and by MSA status. Compared with the

national average, the PRF completion

rate was higher in the East South

Central Division (44.3%) but was lower

in the New England Division (32.7%).

The PRF completion rate outside of
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Page 6 [ Series 2, No. 171

MSAs (43.3%) was also higher than the

national average.

Statistically significant chi-square

associations were found between PRF

completion status and the following

characteristics: physician specialty,

specialty type, practice type, and annual

visit volume. PRFs were completed

more frequently than the national

average by general or family

practitioners (44.1%) and pediatricians

(48.6%) but were completed less

frequently by specialists in

cardiovascular diseases (31.9%) and

oncologists (31.6%). Physicians in

primary care specialties completed

PRFs (41.7%) at a higher rate than

nationally, while the reverse was found

for physicians in surgical specialties

(34.6%). A higher-than-national PRF

completion rate was observed among

solo practitioners (42.3%). PRF

completion rates in the 26th–50th

percentile and in the 51st–75th

percentile of annual visit volumes

were significantly lower than the

national rate (30.2% and 27.5%,

respectively), while completion rates

in the 0–25th percentile and the

67th–100th percentile were

significantly higher than the national

rate (49.5% and 46.3%, respectively).

The association between

distributions by PRF completion status

and state location of the office where

the physician saw the most visits during

his or her reporting week was

statistically significant. Compared with

the national average, the PRF

completion rate was higher in five

states: Iowa, Alabama, Tennessee,

Oklahoma, and Utah. The reverse was

found in four states: Ohio, Minnesota,

Maryland, and South Carolina. The

higher-than-national PRF completion

rates in Alabama (51.9%) and Tennessee

(46.0%) (Table 4) contributed to the

higher-than-national PRF completion

rate in the East South Central Division

(Table 3).

Response for visit-level

estimates

To evaluate the potential for

nonresponse bias in visit-level statistics,

weighted percentages of expected PRFs

were compared with percentages of

completed PRFs by physician

characteristic. Overall, an estimated

221,081 PRFs could have been

completed if all in-scope sample

physicians had completed their expected

numbers of PRFs; however, only 76,330

PRFs were completed. Differences

observed in the weighted distributions of

expected and completed PRFs (Tables 5

and 6) were somewhat similar to those

observed among physicians providing

any PRFs (Tables 3 and 4). That is,

percentages of expected PRFs differed

from the corresponding percentages of

completed PRFs for each Census

division (with the exception of East

North Central and Mountain); each

MSA status; the specialties of pediatrics,

psychiatry, oncology, and other

specialties; each specialty type; and each

annual visit quartile (Table 5). Similarly,

the percentages of expected PRFs

differed from the corresponding

percentages of completed PRFs in 15

states (Table 6), and differences were

observed between physicians completing

and not completing PRFs in 13 states

(Table 4).

Completion of PRFs represents

response at the visit level (Tables 5

and 6). Compared with the percentage

of expected PRFs completed nationally

(35.0% weighted), the percentage of

expected PRFs completed in the West

North Central Division was higher,

while lower percentages were completed

in the Middle Atlantic and South

Atlantic divisions. Compared with the

national percentage, the percentage

completed outside of MSAs was higher.

PRF completion percentages also varied

by physician specialty. Compared with

the national percentage, higher

percentages of expected PRFs were

completed by general or family

practitioners and pediatricians, and

lower percentages were completed by

orthopedic surgeons, psychiatrists,

oncologists, and other specialties.

Consequently, physicians in primary

care specialties completed a higher

percentage of expected PRFs than the

percentage completed nationally, while

lower percentages of expected PRFs

were completed by physicians in the

other two specialty types. Compared

with the national percentage, higher

percentages of expected PRFs were

completed by physicians in the first and

fourth quartiles for annual visit volume,

and lower percentages were completed

by physicians in the second and third

quartiles for annual visit volume.

Compared with the national

percentage, lower percentages of

expected PRFs were completed in

Florida and Maryland, which may have

contributed to the low percentages of

PRFs completed in the South Atlantic

Division. Compared with the national

percentage, higher percentages of

expected PRFs were completed in Iowa,

Kansas, Oklahoma, and Utah, and lower

percentages were completed in Oregon

(Table 6).

2010–2012 PRF completion,

participation, and response

rates

Historically, NAMCS reports have

defined three groups of physicians by

the extent of their response to PRFs:

participating physicians, physicians

completing any PRF, and physicians

with full or adequate PRF response

(Appendix I). Thus far, this study has

focused on physicians completing any

PRF, to assess potential nonresponse

biases among these physicians compared

with the full sample of in-scope

physicians.

Prior to 2002, NAMCS response

rates were identical to that of

participating physicians, defined as

physicians who either completed any

PRF or saw no patients because they

were unavailable during their sample

week (Appendix I). Starting in 2002,

NAMCS response rates were defined as

physicians with full or adequate PRF

response, to better reflect changes in the

nonresponse adjustments included in

visit survey weights. The following

Figure shows that since 2002, the rates

of NAMCS participation, PRF

completion, and full PRF response

(unweighted) have all been declining.

Regardless of year, the percentage of

physicians completing any PRF is less

than the percentage of participating

physicians and the percentage of

physicians with full or adequate PRF

response because the latter two

definitions of physicians include

physicians who were unavailable to
 

 

 

 

Series 2, No. 171 [ Page 7

completed less than one-half of expected 

PRFs increased in 2012 (6.9%)

compared with 2010 and 2011 (2.4%

and 3.1%, respectively).

 

 

 

 

 

 

 

Full response to the PRF means

physicians completed 50% or more of

their expected sample visits or were

unavailable during their sample week.

By this measure, the 2012 weighted

percentage of physicians with full PRF

response (39.4%) was lower than in

 2010 (56.7%) and 2011 (53.4%). All

three measures declined from 2011 to 

2012.

 

Nonresponse Bias Analyses

 Physician-level estimates

Survey weights were adjusted for

nonresponse to produce final

physician-level estimates based on each

of two sets of physicians: induction

interview respondents and PRF

Figure. Survey participation, full Patient Record Form response, and Patient Record Form

completion rates: National Ambulatory Medical Care Survey, 2002–2012

see patients during their sample week

and thus saw no patients during that

time period. For example, 750

sampled in-scope physicians were

unavailable in 2012.

Analysis of differences between

physicians with full or adequate PRF

response and nonresponders (those who

saw patients but had zero PRFs or PRFs

for less than 50% of their expected

sample) in 2012 is presented in

Appendix III.

The Table below presents the

percentages of physicians by the three

definitions of response to the PRF, by

year. In this section, to assess possible

effects on response to the PRF due to

changes in the 2012 NAMCS survey

design, data collection methodology, and

other unspecified factors, PRF

completion rates for the 2012 NAMCS

are compared with those from the 2010

and 2011 NAMCS, as well as

alternative definitions of response to

PRFs. For this comparison, physicians

selected in the stratum of community

health centers were excluded from 2010

and 2011 estimates.

Between 2010 and 2011, the

percentages of PRF completers were

similar. However, this percentage

decreased significantly from 2011

(49.3%) to 2012 (38.4%). The

percentage of physicians completing

PRFs in 2010 (51.0%) was also

significantly higher than the

2012 percentage.

NAMCS participants are in-scope

physicians who either completed any

PRF or were unavailable during their

sample week and hence had no patient

visits on which to complete PRFs. The

lower NAMCS participation rate in

2012 was influenced by the lower

percentage completing any PRF (38.4%)

compared with 2010 and 2011 PRF

completion rates (51.0% and 49.3%,

respectively). No change was seen in the

percentage of physicians unavailable in

their sample weeks during 2010–2012.

The percentage of in-scope physicians

completing 50% or more of expected

PRFs in 2012 was significantly lower

(31.5%) than in 2010 (48.6%) and

2011 (46.2%). The percentage of

in-scope sample physicians who

completers (Appendix II). To assess how

well the adjustments worked, the final

survey estimates are compared with

estimates based on the total sample of

eligible physicians. Potential

nonresponse bias is defined as a

statistically significant difference

between the estimated distribution based

on the total sample of eligible

physicians and the estimated distribution

based on respondents only. For this

analysis, a bias of less than

2.0 percentage points is subjectively

considered low. The potential bias in

physician-level estimates is discussed

below.

Tables 7–10 show estimated percent

distributions of physicians by their

characteristics. The first set of estimates

in each table is based on the full sample

of in-scope physicians, using calibrated

sampling weights only, while the second

set is based only on induction interview

respondents, using weights adjusted for

nonresponse to the induction interview

(described in Appendix II) (Tables 7 and

8). Tables 9 and 10 compare estimates

based on the total in-scope sample using

the calibrated sampling weights, with

estimates based on PRF completers

using weights adjusted for PRF

noncompleters.
Page 8 [ Series 2, No. 171

Physician estimates based on

induction interview respondents

Although response differences were

seen by Census division and physician

specialty, as noted previously (Table 1),

no statistically significant bias was seen

in the distributions by division and

physician specialty after adjustment for

nonresponse (Table 7). A statistically

significant potential for bias by MSA

Table. Percent of in-scope sample physicians, by type of physician response to Patient

Record Form: United States, 2010–2012

Percent of physicians (weighted)
 

PRF components of response 2010 2011 2012
 

Completed any PRF1,2 . . . . . . . . . . . . . . . . . . . . . . 51.0 49.3 38.4

Completed at least one-half of expected PRFs1,2 . . . . 48.6 46.2 31.5

Completed fewer than one-half of expected

PRFs1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 3.1 6.9
 

Unavailable during sample week . . . . . . . . . . . . . . . . 8.1 7.1 7.8
 

Participation rate1,2,4 . . . . . . . . . . . . . . . . . . . . . . . 59.1 56.5 46.2
 

Responded fully1,2,5

. . . . . . . . . . . . . . . . . . . . . . . . 56.7 53.4 39.4
 

status of the interview location persisted

after nonresponse adjustments were

applied, but the bias was small

(1.0 percentage point). No statistically

significant differences were noted in the

estimated percentages for each targeted

state; bias estimates were zero or

minimal (at most 0.1 percentage point)

(Table 8).

Physician estimates based on

PRF completers

Overall, no statistically significant

differences were seen in estimated

physician distributions from the two

samples by physician age, sex, Census

division, MSA status, type of doctor

(M.D. or D.O.), physician specialty, and

specialty type (Table 9). Biases among

these variables were zero (Census

division and physician specialty) or less

than 2.0 percentage points. However,

after adjustment for nonresponse, the

estimated percentage of physicians in

solo practice (26.7%) was greater than

the full sample estimated percentage

(23.7%), with a positive bias of

3.0 percentage points. Conversely, the

final survey estimate for the percentage

of physicians in group or HMO

practices (56.6%) was lower than the

full sample estimated percentage

(59.4%), resulting in a negative bias of

2.8 percentage points for these

physicians. Differences were noted

between estimated percentages of

physicians in each annual visit volume

quartile. The final survey estimates for

percentages of physicians with annual

visit volume in the first and fourth

quartiles were biased upward by 8.2 and

3.8 percentage points, respectively, while

the estimated percentages of physicians

with annual visit volumes in the second

and third quartiles were

1Significant difference between 2010 and 2012 percentages (p < 0.05).
 

2Significant difference between 2011 and 2012 percentages (p < 0.05).
 

3Physicians who completed fewer than one-half of expected PRFs are considered to have responded minimally.
 

4Participating physicians completed any PRF or were unavailable during sample week.
 

5Physicians who responded fully completed at least one-half of expected PRFs or were unavailable during sample week.
 

NOTES: PRF is Patient Record Form. Visits to physicians in community health centers were excluded. Estimates are weighted by
 

calibrated sampling weights.
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2010–2012.
 

understated by 5.1 and 6.9 percentage

points, respectively.

After nonresponse adjustments,

in all but four of the targeted states no

statistical differences were seen between

the distribution of physicians estimated

on the basis of PRF completers and the

distribution estimated on the basis of

the full in-scope sample. A positive

difference was found between estimated

percentages based on the full sample

and those based on the PRF completers

in New Jersey, with a bias of

0.7 percentage point. Negative

differences were seen between estimated

proportions based on the full sample

and the PRF completing physicians in

three states (Pennsylvania, Ohio, and

Maryland), with biases ranging from

–0.4 to –0.9 percentage points. Among

all targeted states, biases were less than

1.0 percentage point (Table 10).

Physician biases computed from

an external data source

Another technique for identifying

potential nonresponse bias is to compare

survey estimates with comparable

estimates from an external data source.

Table 11 presents estimates from the

2012 National Electronic Health

Records Survey (NEHRS) and the 2012

NAMCS.

Estimated percentages of physicians

from NEHRS and both NAMCS

respondent types were similar across

physician age group, sex, and

multispecialty status (solo or single

specialty compared with multispecialty).

Estimates from both of the NAMCS

physician respondent types for the

percentage of physicians practicing in

MSAs were significantly greater than

the corresponding estimate from

NEHRS respondents, with biases of

3.4 percentage points for estimates based

on induction interview respondents and

2.9 percentage points for estimates based

on PRF completers. A negative bias of

–1.5 percentage points was seen in

estimates for general surgeons based on

both NAMCS respondent types,

compared with those based on NEHRS

respondents. Among estimates for

physicians in surgical specialties,

negative biases were observed in those

from both types of NAMCS respondents

(–3.1 and –3.0 percentage points,

respectively). Conversely, positive biases

of 3.6 and 3.4 percentage points,

respectively, were observed for estimates

of physicians in medical specialties

based on both types of NAMCS

respondents. Biases were also observed

by practice size. Positive biases of

7.2 percentage points were observed in

both estimates for solo practitioners,

while negative biases of –6.8 and

–7.1 percentage points, respectively,

were observed for estimates of

physicians in practices with 11 or

more physicians, based on induction

interview respondents and PRF

completers.
Series 2, No. 171 [ Page 9

Visit-level estimates

Bias at the visit level was evaluated

by comparing the final survey estimates

for percentages of visits with the

estimated percentages of visits based on

annual visit volumes for the total

eligible physician sample weighted by

the physician calibrated sampling

weights only. After adjustment for

nonresponse, biases by selected Census

divisions and specialties were less than

1.0 percentage point. Although the

difference between the two estimates for

visits to oncologists was statistically

significant, the difference was small

(–0.4 percentage point) (Table 12).

Although bias toward overestimating

solo practitioners and underestimating

physicians in larger practices (group or

HMO) persisted after adjustments for

nonresponse among physicians

providing visit data (Table 9), biases

computed at the visit level for the same

variables were not statistically

significant (Table 12). After adjustment

for nonresponse, biases of –1.6

percentage points persisted for

physicians located within MSAs and of

1.6 percentage point for physicians

outside MSAs. After adjustment for

nonresponse, a positive bias of

8.4 percentage points was observed for

estimated visits to physicians in the first

quartile of annual visit volumes, and a

negative bias of –5.9 percentage points

persisted for estimated visits to

physicians in the third quartile of annual

visit volumes.

After adjustment for nonresponse,

biases for targeted states were less than

1.0 percentage point. Although

differences between total eligible sample

and final survey estimates for the

percentages of visits in Connecticut and

Utah were significant, the differences

were small (0.3 and 0.1 percentage

point, respectively) (Table 13).

Discussion

This study examines potential

biases in physician-level estimates due

to physician nonresponse in the 2012

NAMCS. The study also examines the

potential for bias in visit-level

statistics due to noncompletion of

survey forms for expected sample

visits.

For the first time, the 2012

NAMCS was redesigned to produce

state estimates. Specifically, estimates

were produced for each of the 34 most

populous states and nine Census

divisions. Physician response to the

physician-level induction interview

(59.7%) was higher than to PRFs

(38.4%). The difference in response

may reflect increased challenges

of completing PRFs using the

computerized tool during its first year

of implementation, or to other

unmeasured characteristics. This

interpretation is suggested by the

similarity of PRF completion rates in

2010 (51.0%) and 2011 (49.3%)

compared with a lower completion rate

in 2012 (38.4%). Other measures of

response to PRFs follow a similar

pattern.

Shared similarities in physician

response rates were noted at both

physician response levels (induction

interview and PRF completion).

Response rates did not vary by

physician age, sex, and type of doctor

(M.D., D.O.) for both levels of

physician response. Relative to the

overall response rate, however, response

rate differences at both levels of

physician response were observed in

selected categories of the following

characteristics: Census division,

physician specialty, specialty type,

practice type, and state. In addition,

compared with the overall PRF

completion rate, PRF completion was

higher among physicians outside

MSAs and among physicians in the

first and fourth quartiles of annual

visit volumes; PRF completion was

lower among physicians in the second

and third quartiles than was found

overall.

In addition to the physician rates for

completing PRFs, visit-level response

rates (rates at which PRFs were

completed for expected sample visits)

were estimated (Tables 5 and 6). The

pattern of differences between the

percentages of PRFs expected to be

completed by various subgroups

compared with the national percentage

were somewhat similar to patterns

observed for physicians completing

PRFs. That is, the national percentage

of expected PRFs completed differed

from the percentage in selected Census

divisions, by MSA status, among

selected physician specialties, by

specialty type, by annual visit volume,

and among selected states.

Note that the percentage of

expected PRFs may overestimate the

actual percentage due to assumptions

used in calculating this estimate. The

estimated percentage would be lower,

for example, if 24 (the prior year

averages for number of PRFs) was

always assumed to be the expected

number of sample visits when sampling

interval information was missing.

Because this assumption affected the

denominator for the percentage of PRFs

expected to be completed, the resulting

visit-level response rate is probably a

maximum value for this percentage.

Final survey estimates of physicians

based on physicians completing the

induction interview and those based on

PRF completers were produced using

weights adjusted for nonresponse.

Adjustments for nonresponse were made

within cells defined by many of the

variables for which response rates

differed from overall national response

rates, including Census division, MSA

status, physician specialty, state, and

annual visit volume. After adjustment

for nonresponse, biases in percent

distributions by physician specialty,

MSA status, and Census division or

target state were either eliminated or

differed by less than 2.0 percentage

points for both the estimates based on

induction interview respondents

(Tables 7 and 8) and those based on

PRF completers (Tables 9 and 10).

However, certain potential biases among

estimates based on PRF completers

persisted. After adjustment for PRF

noncompleters, the percentage for solo

practitioners was overstated by

3.0 percentage points, while the

percentage of physicians in group

practices and HMOs was understated by

2.8 percentage points. In addition, the

estimated percentages of physicians with

annual visit volumes in the first and

fourth quartiles were biased upward by

8.2 and 3.2 percentage points,

respectively, while the percentages of

physicians with annual visit volumes in
Page 10 [ Series 2, No. 171

the second and third quartiles were

understated by 5.1 and 6.9 percentage

points, respectively.

After adjustment for nonresponse,

biases in percentage estimates of visits

(compared to the weighted annual visit

volume based on the total in-scope

physician sample) by physician

specialty, MSA status, and Census

division or targeted state were either

eliminated or differed by less than

2.0 percentage points (1.6% among

MSA visits, –1.6% among non-MSA

visits, –0.4% among oncologist visits,

and 0.2% among Utah visits). Biases in

visit estimates were nearly eliminated

among visits in the second and fourth

quartiles of annual visit volume after

adjustments for nonresponse were

applied. Biases in the first (8.4%) and

third (–5.9%) annual visit volume

quartiles, however, persisted.

Note that although bias toward

overestimating solo practitioners and

underestimating physicians in larger

practices (group or HMO) persisted after

adjustments for nonresponse among

physicians completing PRFs, biases

computed at the visit level for the same

variables were not statistically

significant (Table 12). In addition,

when 2010 through 2012 NAMCS

visit estimates were compared, no

statistically significant differences were

seen between percentages of visits

by practice size category (solo,

2 physicians, 3–5 physicians,

6–10 physicians, and 11 or more

physicians) (9–11).

To benchmark 2012 NAMCS

estimates to an external data source,

physician-level percentage estimates

based on both NAMCS respondent types

were compared with estimates from the

2012 NEHRS. Similar to comparisons

with estimates based on the full

NAMCS in-scope sample, biases based

on NEHRS as the reference were

observed by MSA status, physician

specialty, and specialty type. The biases,

however, were larger in magnitude. For

example, compared with NEHRS

estimates, NAMCS estimates were

biased by 2.9 percentage points within

or outside MSAs (Table 11). These

differences were larger than those

observed between estimates based on

the full NAMCS sample and the

induction interview respondents

(1.0 percentage point) (Table 7) or the

PRF completers (0.5 percentage point)

(Table 9). Similarly, biases of larger

magnitude between NEHRS and

NAMCS estimates were also observed

by physician specialty and specialty

type. Biases between the two surveys’

estimates were observed by practice

size. Compared with NEHRS estimates,

NAMCS estimates based on both

respondent types were biased toward

solo practitioners by 7.2 percentage

points, and were understated by 6.8 and

7.1 percentage points among the two

respondent types, respectively, for

physicians in practices with 11 or more

physicians. Due to differences in data

collection mode, respondent type, and

other survey differences, however, it is

not clear which set of distributions is

the correct distribution.

Limitations

Results of this study are subject to

several limitations. First, with the

exception of annual visit volumes,

physician characteristics used in this

study were limited to those available in

the sampling frame, with updates from

the survey. Second, unforeseen

challenges encountered in data

collection and processing during this

first year of computerized data

collection for NAMCS may have

affected response, as indicated by the

PRF completion rates from 2010

through 2012. Third, information on

numbers of visits seen by physicians in

normal practice weeks, and thus

numbers of sample visits to expect, was

missing a greater percentage of the time

than experienced in prior years, which

affected estimates for visit response

rates and visit estimates. Finally,

comparison of estimates from the

external NEHRS data source may be

subject to response bias and should not

be considered the ‘‘gold standard.’’

Further research is needed to both

measure and evaluate the effect of these

aspects on physician response.

Conclusions
 

The 2012 NAMCS sample was

redesigned to produce state estimates for

the first time in the survey’s history.

Also for the first time, a computerized

survey instrument was used to collect

NAMCS data. Implementation of the

new data collection mode may have

influenced lower physician completion

of PRFs (for visit-level data) compared

with 2010 and 2011. After adjustment

for nonresponse by MSA status, Census

division or targeted state, and physician

specialty categories, no or minimal

biases (less than 2.0 percentage points)

were observed by these characteristics

between physician estimates based on

the full in-scope physician sample and

physician estimates based on either of

the two NAMCS respondent types

(induction interview respondents and

PRF completers). After adjustment for

nonresponse among sample visits, no or

minimal biases (less than 2.0 percentage

points) were observed by the same

characteristics. Biases may exist for

characteristics that were not used in

adjusting for nonresponse.

References

1.	 National Center for Health Statistics.

2012 NAMCS microdata file

documentation. Hyattsville, MD. 2015.

Available from: ftp://ftp.cdc.gov/pub/

Health_Statistics/NCHS/Datasets/

NAMCS.

2.	 Hing E, Cherry DK, Woodwell DA.

National Ambulatory Medical Care

Survey: 2003 summary. Advance data

from vital and health statistics; no 365.

Hyattsville, MD: National Center for

Health Statistics. 2005. Available from:

http://www.cdc.gov/nchs/data/ad/

ad365.pdf.

3.	 Hsiao CJ, Hing E, Ashman JJ. Trends

in electronic health record system use

among office-based physicians: United

States, 2007–2012. National health

statistics reports; no 75. Hyattsville,

MD: National Center for Health

Statistics. 2014. Available from:

http://www.cdc.gov/nchs/data/nhsr/

nhsr075.pdf.
Series 2, No. 171

[ Page 11

4.	 Groves RM. Nonresponse rates and

nonresponse bias in household surveys.

Public OpinQ 70(5):646–75. 2006.

5.	 Johnson TP, Wislar JS. Response

rates and nonresponse errors in

surveys. JAMA 307(17):1805–6. 2012.

6.	 Hsiao CJ, Hing E. Use and

characteristics of electronic health

record systems among office-based

physician practices: United States,

2001–2012. NCHS data brief, no 111.

Hyattsville, MD: National Center for

Health Statistics. 2012. Available from:

http://www.cdc.gov/nchs/data/databriefs/

db111.htm.pdf.

7.	 Hing E, Hsiao CJ, Beatty P.A

comparison of mail and face-to-face

responses ina dual-mode survey of

physicians. Proceedings of the

American Statistical Association

Section on Survey Research Methods.

2010.

8.	 Hing E, Hsiao CJ, Beatty P, Decker SL.

Mode and respondent effects ina

dual-mode survey of physicians:

2008–2009. Proceedings of the

American Statistical Association

Section on Survey Research Methods.

2011.

9.	 National Center for Health Statistics.

2010 NAMCS microdata file. 2012.

Available from: ftp://ftp.cdc.gov/pub/

Health_Statistics/NCHS/Datasets/

NAMCS/.

10.	 National Center for Health Statistics.

2011 NAMCS microdata file. 2015.

Available from: ftp://ftp.cdc.gov/pub/

Health_Statistics/NCHS/Datasets/

NAMCS/.

11.	 National Center for Health Statistics.

National Ambulatory Medical Care

Survey: 2012 state and national

summary tables. 2015. Available from:

http://www.cdc.gov/nchs/data/ahcd/

namcs_summary/2012_namcs_web_

tables.pdf.
Page 12 [ Series 2, No. 171

Table 1. In-scope sample physicians and their weighted percent distributions and rates of response to the physician induction interview, by

physician characteristics: National Ambulatory Medical Care Survey, 2012

Induction interview respondent status

In-scope Induction

Number of sample Percent Percent interview

in-scope percent distribution of distribution of response

sample distribution respondents3 nonrespondents4 rate5

Physician characteristic1 physicians2 (weighted) (weighted) (weighted) (weighted)

All office-based physicians . . . . . . . . . . . . . . . . . . . 9,574 100.0 100.0 100.0 59.7

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,741 40.4 39.6 41.6 58.6

50 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,833 59.6 60.4 58.4 60.5

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,239 71.6 71.8 71.3 59.9

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,335 28.4 28.2 28.7 59.4

Census division location of interview6

New England7 . . . . . . . . . . . . . . . . . . . . . . . . . . . 684 6.2 5.3 7.5 51.3

Middle Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . . . 812 15.3 15.3 15.4 59.6

East North Central7 . . . . . . . . . . . . . . . . . . . . . . . . 1,166 13.0 14.2 11.3 65.1

West North Central . . . . . . . . . . . . . . . . . . . . . . . . 1,067 5.9 5.8 6.0 58.9

South Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,593 18.8 18.3 19.4 58.4

East South Central7. . . . . . . . . . . . . . . . . . . . . . . . 1,092 5.7 6.2 5.1 64.1

West South Central . . . . . . . . . . . . . . . . . . . . . . . . 1,039 10.6 10.3 11.1 58.0

Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,018 6.9 7.0 6.8 60.4

Pacific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,103 17.5 17.6 17.4 60.0

Metropolitan status8

MSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,473 91.7 91.6 91.9 59.7

Non-MSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,101 8.3 8.4 8.1 60.6

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . . . . . . . . 9,083 94.1 93.9 94.5 59.6

Doctor of osteopathy . . . . . . . . . . . . . . . . . . . . . . . 491 5.9 6.1 5.5 62.5

Physician specialty6,9

General or family practice7 . . . . . . . . . . . . . . . . . . . 1,265 17.1 18.4 15.2 64.3

Internal medicine . . . . . . . . . . . . . . . . . . . . . . . . . 811 12.8 12.0 14.0 55.9

Pediatrics7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688 10.3 12.1 7.7 70.0

General surgery . . . . . . . . . . . . . . . . . . . . . . . . . . 391 2.7 2.8 2.6 61.5

Obstetrics and gynecology . . . . . . . . . . . . . . . . . . . 509 7.2 7.1 7.4 58.7

Orthopedic surgery7

. . . . . . . . . . . . . . . . . . . . . . . . 555 4.5 4.1 5.2 53.9

Cardiovascular diseases7 . . . . . . . . . . . . . . . . . . . . 416 3.6 3.1 4.4 51.2

Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 2.5 2.4 2.5 59.5

Urology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 1.9 1.8 2.1 55.7

Psychiatry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597 5.9 5.8 6.0 59.1

Neurology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 2.3 2.3 2.3 59.5

Ophthalmology . . . . . . . . . . . . . . . . . . . . . . . . . . . 448 3.8 3.7 3.9 58.5

Otolaryngology . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 1.9 1.8 2.0 57.6

Oncology7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416 1.9 1.6 2.3 51.4

Allergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 0.9 0.9 0.8 62.7

Pulmonology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 1.8 1.9 1.7 62.4

All other specialties . . . . . . . . . . . . . . . . . . . . . . . . 1,705 19.0 18.2 20.1 57.5

Specialty type6,9

Primary care7 . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,204 46.7 48.8 43.6 62.4

Surgical7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,411 20.7 19.1 23.2 54.9

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,959 32.5 32.1 33.2 58.9

See footnotes at end of table.
Series 2, No. 171 [ Page 13

Table 1. In-scope sample physicians and their weighted percent distributions and rates of response to the physician induction interview, by

physician characteristics: National Ambulatory Medical Care Survey, 2012—Con.

Induction interview respondent status

In-scope Induction

Number of sample Percent Percent interview

in-scope percent distribution of distribution of response

sample distribution respondents3 nonrespondents4 rate5

Physician characteristic1 physicians2 (weighted) (weighted) (weighted) (weighted)

Practice type

Solo7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,089 23.7 25.1 21.7 63.2
 

Two physicians. . . . . . . . . . . . . . . . . . . . . . . . . . . 426 4.4 4.3 4.5 58.5
 

Group or HMO10. . . . . . . . . . . . . . . . . . . . . . . . . . 5,993 59.4 58.4 61.0 58.7
 

Medical school or government . . . . . . . . . . . . . . . . . 116 1.3 1.3 1.3 58.9
 

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.1 1.2 0.9 66.0
 

Unclassified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 862 10.0 9.7 10.6 57.7
 

1From the master files of the American Medical Association and the American Osteopathic Association; updated during the survey.

2Physicians confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and anesthesiology.

3In-scope sample physicians who satisfied criteria required for respondent status relative to the physician induction interview.

4In-scope sample physicians who did not satisfy criteria required for respondent status relative to the physician induction interview.

5Values represent response rates among sample in-scope physicians with the specified characteristics. Numerators are the numbers of sample in-scope physicians with the characteristics who are also

considered respondents to the physician induction interview. Denominators are all sample in-scope physicians with the specified characteristics.

6Chi-square test of association between physician response status and indicated physician characteristic is significant ( p < 0.05).

7Response rate is significantly different from national response rate ( p < 0.05).

8MSA is metropolitan statistical area.

9Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/

Dataset_Documentation/NAMCS/doc2012.pdf).

10HMO is health maintenance organization.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Page 14 [ Series 2, No. 171

Table 2. In-scope sample physicians and their weighted percent distributions and rates of response to the physician induction interview, by

division and state where interview occurred: National Ambulatory Medical Care Survey, 2012

[Weighted by calibrated sampling weights only]

Induction interview respondent status

In-scope Induction

Number of sample Percent Percent interview

in-scope percent distribution of distribution of response

Census division and state sample distribution respondents3 nonrespondents4 rate5

where induction interview occurred1 physicians1,2 (weighted) (weighted) (weighted) (weighted)

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,574 100.0 100.0 100.0 59.7

New England

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 1.6 1.6 1.8 56.8

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 2.7 2.4 3.0 54.4

Remainder states (ME,NH,RI,VT)6. . . . . . . . . . . . . . . 160 1.9 1.4 2.7 42.3

Middle Atlantic

New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 3.9 3.6 4.4 54.5

New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 7.4 7.4 7.6 59.1

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 4.0 4.3 3.4 65.5

East North Central

Illinois6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 3.9 4.4 3.2 67.3

Indiana6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 2.0 2.3 1.5 69.7

Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 2.3 2.1 2.5 55.1

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 3.0 3.2 2.6 65.0

Wisconsin6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 1.9 2.1 1.5 68.3

West North Central

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 0.8 0.9 0.7 63.4

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 0.8 0.8 0.9 56.2

Minnesota6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 1.9 1.5 2.4 47.9

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 1.2 1.3 1.0 66.5

Remainder states (NE,ND,SD) . . . . . . . . . . . . . . . . . 121 1.2 1.4 1.0 67.0

South Atlantic

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 7.0 7.2 6.8 60.9

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 2.8 2.6 3.2 54.2

Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 2.2 2.1 2.3 57.6

North Carolina6 . . . . . . . . . . . . . . . . . . . . . . . . . . 198 2.2 1.9 2.7 51.6

South Carolina6 . . . . . . . . . . . . . . . . . . . . . . . . . . 188 1.0 0.9 1.3 48.8

Virginia6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 2.4 2.7 2.0 66.5

Remainder states (DC,DE,WV). . . . . . . . . . . . . . . . . 187 1.0 1.0 1.0 59.7

East South Central

Alabama6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 1.4 1.6 0.9 72.8

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 1.2 1.2 1.3 58.5

Mississippi6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 0.7 0.6 0.8 50.5

Tennessee6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323 2.5 2.7 2.1 66.0

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 0.7 0.7 0.7 62.3

Louisiana6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 1.4 1.2 1.7 51.0

Oklahoma6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 0.9 1.1 0.7 70.5

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 7.6 7.3 8.0 57.4

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 1.9 2.1 1.6 66.1

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 1.8 1.8 1.8 59.5

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 0.8 0.9 0.6 68.0

Remainder states (ID,NM,MT,NV,WY). . . . . . . . . . . . . 213 2.4 2.1 2.7 53.9

See footnotes at end of table.
Series 2, No. 171 [ Page 15

Table 2. In-scope sample physicians and their weighted percent distributions and rates of response to the physician induction interview, by

division and state where interview occurred: National Ambulatory Medical Care Survey, 2012—Con.

[Weighted by calibrated sampling weights only]

Induction interview respondent status

In-scope Induction

Number of sample Percent Percent interview

in-scope percent distribution of distribution of response

Census division and state sample distribution respondents3 nonrespondents4 rate5

where induction interview occurred1 physicians1,2 (weighted) (weighted) (weighted) (weighted)

Pacific

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344 13.3 13.6 12.7 61.4
 

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270 1.6 1.4 1.7 54.9
 

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 1.9 1.8 2.1 55.8
 

Remainder states (AK,HI) . . . . . . . . . . . . . . . . . . . . 275 0.8 0.7 0.8 57.1
 

1Chi-square test of association is significant ( p < 0.05) between physician response and state location of office.
 

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

3Responding physicians are in-scope sample physicians who satisfied criteria required for respondent status to the physician induction interview.
 

4Nonresponding physicians are in-scope sample physicians who did not satisfy criteria required for respondent status to the physician induction interview.
 

5Values represent response rates among sample in-scope physicians with an office in the specified state. Numerators are the numbers of sample in-scope physicians with an office in the specified
 

state who are also considered respondents to the physician induction interview. Denominators are all sample in-scope physicians in the specified state.
 

6Response rate is significantly different from total national rate ( p < 0.05).
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
 
Page 16 [ Series 2, No. 171

Table 3. In-scope sample physicians, their weighted percent distributions by Patient Record Form status, and Patient Record Form

completion rate, by physician characteristics: National Ambulatory Medical Care Survey, 2012

[Weighted by calibrated sampling weights only]

PRF completion status

In-scope Percent Percent

Number of sample distribution distribution

in-scope percent of PRF of PRF PRF

sample distribution completers3 noncompleters4 completion

Physician characteristic1 physicians2 (weighted) (weighted) (weighted) rate5

All office-based physicians . . . . . . . . . . . . . . . . . . . 9,574 100.0 100.0 100.0 38.4

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,741 40.4 39.4 41.0 37.5

50 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,833 59.6 60.6 59.0 39.1

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,239 71.6 72.5 71.0 38.9

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,335 28.4 27.5 29.0 37.2

Census division6,7

New England8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 684 6.2 5.3 6.8 32.7

Middle Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . . . 811 15.3 14.4 15.9 36.2

East North Central . . . . . . . . . . . . . . . . . . . . . . . . 1,166 13.0 12.7 13.2 37.6

West North Central . . . . . . . . . . . . . . . . . . . . . . . . 1,067 5.9 5.9 5.9 38.5

South Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,593 18.8 17.8 19.4 36.4

East South Central8. . . . . . . . . . . . . . . . . . . . . . . . 1,092 5.7 6.6 5.2 44.3

West South Central . . . . . . . . . . . . . . . . . . . . . . . . 1,040 10.6 11.6 10.0 41.8

Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,017 6.9 6.7 7.0 37.5

Pacific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,104 17.5 18.9 16.6 41.5

Metropolitan status6,9

MSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,473 91.7 90.7 92.4 38.0

Non-MSA8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,101 8.3 9.3 7.6 43.3

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . . . . . . . . 9,083 94.1 93.7 94.4 38.2

Doctor of osteopathy . . . . . . . . . . . . . . . . . . . . . . . 491 5.9 6.3 5.6 41.2

Physician specialty6,10

General or family practice8 . . . . . . . . . . . . . . . . . . . 1,265 17.1 19.7 15.6 44.1

Internal medicine . . . . . . . . . . . . . . . . . . . . . . . . . 811 12.8 11.8 13.4 35.5

Pediatrics8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688 10.3 13.0 8.6 48.6

General surgery . . . . . . . . . . . . . . . . . . . . . . . . . . 391 2.7 2.7 2.8 37.7

Obstetrics and gynecology . . . . . . . . . . . . . . . . . . . 509 7.2 7.0 7.4 37.0

Orthopedic surgery . . . . . . . . . . . . . . . . . . . . . . . . 555 4.5 4.0 4.8 34.1

Cardiovascular diseases8 . . . . . . . . . . . . . . . . . . . . 416 3.6 3.0 4.0 31.9

Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 2.5 2.5 2.4 38.9

Urology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 1.9 1.8 1.9 36.8

Psychiatry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597 5.9 5.3 6.3 34.3

Neurology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 2.3 2.4 2.2 40.7

Ophthalmology . . . . . . . . . . . . . . . . . . . . . . . . . . . 448 3.8 3.7 3.8 37.7

Otolaryngology . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 1.9 1.7 2.0 34.8

Oncology8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416 1.9 1.5 2.1 31.6

Allergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 0.9 1.0 0.8 44.5

Pulmonology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 1.8 1.6 1.9 34.1

All other specialties . . . . . . . . . . . . . . . . . . . . . . . . 1,705 19.0 17.3 20.0 35.0

Specialty type6,10

Primary care8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,204 46.7 50.8 44.2 41.7

Surgical8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,411 20.7 18.7 22.0 34.6

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,959 32.5 30.5 33.8 36.1

See footnotes at end of table.
Series 2, No. 171 [ Page 17

Table 3. In-scope sample physicians, their weighted percent distributions by Patient Record Form status, and Patient Record Form

completion rate, by physician characteristics: National Ambulatory Medical Care Survey, 2012—Con.

[Weighted by calibrated sampling weights only]

PRF completion status

In-scope Percent Percent

Number of sample distribution distribution

in-scope percent of PRF of PRF PRF

sample distribution completers3 noncompleters4 completion

Physician characteristic1 physicians2 (weighted) (weighted) (weighted) rate5

Practice type6

Solo8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,089 23.7 26.2 22.2 42.3

Two physicians. . . . . . . . . . . . . . . . . . . . . . . . . . . 426 4.4 4.8 4.1 42.4

Group or HMO11. . . . . . . . . . . . . . . . . . . . . . . . . . 5,993 59.4 57.0 61.0 36.8

Medical school or government . . . . . . . . . . . . . . . . . 116 1.3 1.3 1.3 37.0

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.1 1.0 1.2 34.6

Unclassified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 862 10.0 9.8 10.2 37.5

Annual visit volume, percentile6,8

0–25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,607 25.0 32.3 20.5 49.5

26–50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,574 25.1 19.8 28.5 30.2

51–75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,155 24.8 17.7 29.2 27.5

76–100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,238 25.0 30.2 21.8 46.3

1Except for annual visit volume, information on characteristics is from the master files of the American Medical Association and the American Osteopathic Association; updated during the survey.
 

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

3Physicians who were in-scope and completed any PRFs.
 

4Physicians who were in-scope but either were unavailable during sample week (saw no patients) or did not complete any PRF if they did see patients in their sample week.
 

5Values represent response rates among sample in-scope physicians with the specified characteristics. Numerators are the numbers of sample in-scope physicians with the characteristics who also
 

completed PRFs. Denominators are all sample in-scope physicians with the specified characteristics.
 

6Chi-square test of association between physician PRF completer status and physician characteristic is significant ( p < 0.05).
 

7Division includes state location of office where the most visits were seen.
 

8PRF completion rate is significantly different from national rate ( p < 0.05).
 

9MSA is metropolitan statistical area.
 

10Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/
 

Dataset_Documentation/NAMCS/doc2012.pdf).
 

11HMO is health maintenance organization.
 

NOTE: PRF is Patient Record Form.
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
 
Page 18 [ Series 2, No. 171

Table 4. In-scope sample physicians, their weighted percent distributions by Patient Record Form status, and Patient Record Form

completion rate, by state location of office where the most visits were seen: National Ambulatory Medical Care Survey, 2012

[Weighted by calibrated sampling weights only]

PRF completion status

Census division and state1

Number of

in-scope

sample

physicians2

In-scope

sample

percent

distribution

(weighted)

Percent

distribution

of PRF

completers3

(weighted)

Percent

distribution

of PRF

noncompleters4

(weighted)

PRF

completion

rate5

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,574 100.0 100.0 100.0 38.4

New England

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 1.6 1.5 1.7 34.4

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 2.7 2.5 2.8 35.3

Remainder states (ME,NH,RI,VT)6. . . . . . . . . . . . . . . 159 1.9 1.4 2.2 27.8

Middle Atlantic

New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 3.9 4.0 3.8 39.8

New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 7.5 7.1 7.7 36.3

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 3.9 3.3 4.3 32.5

East North Central

Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 3.9 4.0 3.9 39.2

Indiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 2.0 2.3 1.8 44.0

Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 2.3 2.1 2.4 36.2

Ohio6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 3.0 2.4 3.4 30.7

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 1.9 1.9 1.8 40.1

West North Central

Iowa6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 0.8 1.0 0.7 46.3

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 0.8 0.9 0.8 41.5

Minnesota6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 1.9 1.4 2.1 29.1

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 1.2 1.3 1.1 41.6

Remainder states (NE,ND,SD) . . . . . . . . . . . . . . . . . 122 1.2 1.4 1.1 42.5

South Atlantic

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 7.0 7.2 6.9 39.4

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 2.8 2.6 2.9 35.9

Maryland6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 2.2 1.6 2.5 28.5

North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 2.3 2.2 2.3 37.7

South Carolina6 . . . . . . . . . . . . . . . . . . . . . . . . . . 187 1.0 0.8 1.2 30.7

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 2.4 2.4 2.4 38.6

Remainder states (DC,DE,WV)6 . . . . . . . . . . . . . . . . 188 1.0 0.9 1.1 30.9

East South Central

Alabama6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 1.4 1.8 1.1 51.9

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 1.3 1.1 1.3 33.9

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 0.7 0.7 0.7 41.5

Tennessee6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322 2.4 2.9 2.1 46.0

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 0.7 0.7 0.7 35.4

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 1.4 1.3 1.5 34.0

Oklahoma6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 0.9 1.1 0.8 46.2

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 7.6 8.6 7.0 43.3

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 1.9 1.8 2.0 36.3

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 1.8 1.9 1.7 41.0

Utah6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 0.8 1.1 0.6 53.7

Remainder states (ID,NM,MT,NV,WY)6 . . . . . . . . . . . . 212 2.4 1.9 2.7 30.9

See footnotes at end of table.
Series 2, No. 171 [ Page 19

Table 4. In-scope sample physicians, their weighted percent distributions by Patient Record Form status, and Patient Record Form

completion rate, by state location of office where the most visits were seen: National Ambulatory Medical Care Survey, 2012—Con.

[Weighted by calibrated sampling weights only]

PRF completion status

Census division and state1

Number of

in-scope

sample

physicians2

In-scope

sample

percent

distribution

(weighted)

Percent

distribution

of PRF

completers3

(weighted)

Percent

distribution

of PRF

noncompleters4

(weighted)

PRF

completion

rate5

Pacific

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 13.3 14.8 12.3 42.8
 

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 1.5 1.4 1.7 34.0
 

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 1.9 2.0 1.9 39.8
 

Remainder states (AK,HI) . . . . . . . . . . . . . . . . . . . . 274 0.7 0.7 0.8 37.1
 

1Chi-square test of association is significant ( p < 0.05) between physician PRF completion status and physician location.
 

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

3Physicians who were in-scope and completed any PRFs.
 

4Physicians who were in-scope but either were unavailable during sample week (saw no patients) or did not complete any PRF if they did see patients in their sample week.
 

5Values represent response rates among sample in-scope physicians with the specified characteristics. Numerators are the numbers of sample in-scope physicians with the characteristics who also
 

completed PRFs. Denominators are all sample in-scope physicians with the specified characteristics.
 

6PRF completion rate is significantly different from total national rate ( p < 0.05).
 

NOTE: PRF is Patient Record Form.
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
 
Page 20 [ Series 2, No. 171

Table 5. Patient Record Forms expected and completed, their weighted percent distributions, and percentage of expected Patient Record

Forms completed, by physician characteristics: National Ambulatory Medical Care Survey, 2012

[Weighted by calibrated sampling weights only]

Number of PRFs Percent distribution of PRFs

Physician characteristic1

Expected

from

in-scope

physician

sample2,3 Completed4

Expected

from

in-scope

physician

sample2,3

(weighted)

Completed4

(weighted)

Percent of

expected

PRFs

completed

(weighted)

All office-based physicians . . . . . . . . . . . . . . . . . . . 221,081 76,330 100.0 100.0 35.0

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87,250 46,493 41.0 40.7 34.8

50 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133,831 29,837 59.0 59.3 35.2

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167,041 58,479 71.7 71.8 35.0

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54,040 17,851 28.3 28.2 34.9

Census division5

New England6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 14,936 4,802 5.8 5.3 32.0

Middle Atlantic6,7 . . . . . . . . . . . . . . . . . . . . . . . . . 17,955 5,242 14.7 12.7 30.2

East North Central . . . . . . . . . . . . . . . . . . . . . . . . 27,083 9,550 13.1 13.4 35.8

West North Central6,7

. . . . . . . . . . . . . . . . . . . . . . . 23,999 9,247 5.7 6.5 39.9

South Atlantic6,7 . . . . . . . . . . . . . . . . . . . . . . . . . . 36,504 10,851 18.9 16.4 30.4

East South Central . . . . . . . . . . . . . . . . . . . . . . . . 25,980 8,912 5.9 5.9 35.0

West South Central6 . . . . . . . . . . . . . . . . . . . . . . . 25,608 9,297 11.4 12.9 39.6

Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24,088 9,767 7.1 7.6 37.5

Pacific6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24,930 8,662 17.3 19.2 38.9

Metropolitan status8

MSA6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194,436 64,870 91.3 89.6 34.4

Non-MSA6,7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26,645 11,460 8.7 10.4 41.8

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . . . . . . . . 209,329 71,607 94.1 93.2 34.7

Doctor of osteopathy . . . . . . . . . . . . . . . . . . . . . . . 11,753 4,723 5.9 6.8 40.1

Physician specialty9

General or family practice7 . . . . . . . . . . . . . . . . . . . 31,945 12,897 18.6 20.9 39.3

Internal medicine . . . . . . . . . . . . . . . . . . . . . . . . . 19,944 6,757 13.3 11.6 30.6

Pediatrics6,7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17,898 8,751 11.7 16.6 49.5

General surgery . . . . . . . . . . . . . . . . . . . . . . . . . . 7,837 2,801 2.3 2.2 33.3

Obstetrics and gynecology . . . . . . . . . . . . . . . . . . . 11,991 4,356 7.3 7.5 35.9

Orthopedic surgery7

. . . . . . . . . . . . . . . . . . . . . . . . 12,394 3,686 4.3 3.6 29.4

Cardiovascular diseases . . . . . . . . . . . . . . . . . . . . . 8,781 2,321 3.2 2.6 28.3

Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,637 2,377 2.6 3.0 41.3

Urology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,805 2,033 1.9 1.9 34.6

Psychiatry6,7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12,190 3,498 5.1 3.8 26.1

Neurology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,080 1,805 2.0 2.0 35.0

Ophthalmology . . . . . . . . . . . . . . . . . . . . . . . . . . . 11,224 4,228 4.0 4.3 37.2

Otolaryngology . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,058 1,883 1.9 1.9 35.4

Oncology6,7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,775 2,585 1.9 1.3 25.1

Allergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,602 3,394 0.9 1.1 42.7

Pulmonology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,512 2,721 1.6 1.4 31.4

All other specialties6,7 . . . . . . . . . . . . . . . . . . . . . . 36,407 10,237 17.4 14.3 28.7

Specialty type9

Primary care6,7. . . . . . . . . . . . . . . . . . . . . . . . . . . 80,336 32,244 50.2 55.9 38.9

Surgical6,7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53,676 17,354 19.7 17.7 31.5

Medical6,7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87,069 26,732 30.1 26.4 30.7

See footnotes at end of table.
Series 2, No. 171 [ Page 21

Table 5. Patient Record Forms expected and completed, their weighted percent distributions, and percentage of expected Patient Record

Forms completed, by physician characteristics: National Ambulatory Medical Care Survey, 2012—Con.

[Weighted by calibrated sampling weights only]

Number of PRFs Percent distribution of PRFs

Physician characteristic1

Expected

from

in-scope

physician

sample2,3 Completed4

Expected

from

in-scope

physician

sample2,3

(weighted)

Completed4

(weighted)

Percent of

expected

PRFs

completed

(weighted)

Practice type

Solo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48,098 16,953 23.4 24.3 36.3

Two physicians. . . . . . . . . . . . . . . . . . . . . . . . . . . 10,373 3,946 4.6 5.2 39.0

Group or HMO10. . . . . . . . . . . . . . . . . . . . . . . . . . 139,375 47,939 60.4 60.3 34.9

Medical school or government . . . . . . . . . . . . . . . . . 2,258 716 1.2 1.1 33.6

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,930 689 0.9 1.0 39.6

Unclassified7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19,048 6,087 9.4 8.1 30.2

Annual visit volume, percentile6,7

0–25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48,095 20,501 19.7 24.6 43.7

26–50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58,549 15,251 24.4 19.1 27.5

51–75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54,449 14,663 27.1 21.2 27.4

76–100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59,988 25,915 28.9 35.1 42.6

1Except for annual visit volume, information on characteristics is from the master files of the American Medical Association and the American Osteopathic Association, updated during the survey.
 

2Number of PRFs expected from each physician is the number of visits seen during the physician’s sample week divided by a sampling interval predetermined on the basis of number of days on which
 

the physician expected to see patients and the number of visits expected during that week. When data for deriving expected numbers of PRFs were missing, the number of expected PRFS was
 

imputed as a minimum of 24 (average number of PRFs received from PRF completers in prior years) or the number of visits seen during the sample week.
 

3In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

4Number of completed PRFs received from PRF completers.
 

5Includes state location of office where the most visits were seen.

6Significant difference between weighted percentages of expected and completed PRFs ( p < 0.05).

7Percentage of expected PRFs completed is significantly different from total national percentage ( p < 0.05).

8MSA is metropolitan statistical area.

9Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/

Dataset_Documentation/NAMCS/doc2012.pdf).

10HMO is health maintenance organization.

NOTE: PRF is Patient Record Form.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Page 22 [ Series 2, No. 171

Table 6. Patient Record Forms expected and completed, their weighted percent distributions, and percentage of expected Patient Record

Forms completed, by state location of office where the most visits were seen: National Ambulatory Medical Care Survey, 2012

Number of PRFs Percent distribution of PRFs

Census division and state

Expected

from

in-scope

physician

sample1,2 Completed3

Expected

from

in-scope

physician

sample1,2

(weighted)

Completed3

(weighted)

Percent of

expected

PRFs

completed

(weighted)

Total . . . . . . . . . . . . . . . . . . . . . . . . . . 221,081 76,330 100.0 100.0 35.0

New England

Connecticut. . . . . . . . . . . . . . . . . . . . . .

Massachusetts. . . . . . . . . . . . . . . . . . . .

Remainder states (ME,NH,RI,VT)4 . . . . . . .

6,040

5,309

3,587

2,114

1,793

895

1.5

2.5

1.8

1.5

2.4

1.4

35.6

33.5

26.9

Middle Atlantic

New Jersey4 . . . . . . . . . . . . . . . . . . . . .

New York . . . . . . . . . . . . . . . . . . . . . . .

Pennsylvania4 . . . . . . . . . . . . . . . . . . . .

6,424

6,391

5,140

1,842

1,925

1,475

3.7

7.2

3.8

3.1

6.4

3.2

29.6

31.1

29.2

East North Central

Illinois . . . . . . . . . . . . . . . . . . . . . . . . .

Indiana4 . . . . . . . . . . . . . . . . . . . . . . . .

Michigan . . . . . . . . . . . . . . . . . . . . . . .

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . .

Wisconsin. . . . . . . . . . . . . . . . . . . . . . .

6,388

6,748

3,782

4,526

5,640

2,282

2,629

1,200

1,285

2,154

4.2

2.1

2.1

2.8

1.9

4.4

2.5

2.1

2.4

2.1

36.9

41.4

33.9

29.9

38.0

West North Central

Iowa4,5 . . . . . . . . . . . . . . . . . . . . . . . .

Kansas4,5 . . . . . . . . . . . . . . . . . . . . . . .

Minnesota4 . . . . . . . . . . . . . . . . . . . . . .

Missouri . . . . . . . . . . . . . . . . . . . . . . . .

Remainder states (NE,ND,SD)4 . . . . . . . . .

6,202

5,261

5,797

4,166

2,575

2,865

2,122

1,598

1,634

1,028

0.8

0.8

1.8

1.2

1.1

1.2

1.0

1.4

1.4

1.4

52.3

43.2

28.6

42.7

42.9

South Atlantic

Florida4,5 . . . . . . . . . . . . . . . . . . . . . . .

Georgia . . . . . . . . . . . . . . . . . . . . . . . .

Maryland4,5. . . . . . . . . . . . . . . . . . . . . .

North Carolina . . . . . . . . . . . . . . . . . . . .

South Carolina. . . . . . . . . . . . . . . . . . . .

Virginia . . . . . . . . . . . . . . . . . . . . . . . .

Remainder states (DC,DE,WV) . . . . . . . . .

7,171

5,753

5,098

4,496

4,340

5,537

4,108

1,859

1,844

1,216

1,690

1,266

1,835

1,141

7.3

2.8

2.2

2.2

1.0

2.4

1.0

6.0

2.5

1.5

2.3

0.9

2.3

0.8

28.9

31.9

24.5

36.6

31.0

33.6

27.6

East South Central

Alabama . . . . . . . . . . . . . . . . . . . . . . .

Kentucky . . . . . . . . . . . . . . . . . . . . . . .

Mississippi4

. . . . . . . . . . . . . . . . . . . . . .

Tennessee . . . . . . . . . . . . . . . . . . . . . .

6,311

5,840

6,210

7,619

2,254

1,817

2,381

2,460

1.4

1.3

0.7

2.5

1.5

1.1

0.9

2.5

36.8

31.0

40.5

34.5

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . .

Louisiana4 . . . . . . . . . . . . . . . . . . . . . .

Oklahoma4,5 . . . . . . . . . . . . . . . . . . . . .

Texas4. . . . . . . . . . . . . . . . . . . . . . . . .

5,732

5,890

5,445

8,541

2,003

1,747

2,300

3,247

0.8

1.5

1.0

8.2

0.8

1.2

1.2

9.6

36.7

29.7

44.9

41.0

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . .

Colorado . . . . . . . . . . . . . . . . . . . . . . .

Utah4,5 . . . . . . . . . . . . . . . . . . . . . . . .

Remainder states (ID,NM,MT,NV,WY) . . . . .

6,968

6,067

6,111

4,943

2,276

2,371

3,515

1,605

2.1

1.8

0.8

2.4

2.0

2.0

1.4

2.2

32.7

40.1

58.6

32.5

See footnotes at end of table.
Series 2, No. 171 [ Page 23

Table 6. Patient Record Forms expected and completed, their weighted percent distributions, and percentage of expected Patient Record

Forms completed, by state location of office where the most visits were seen: National Ambulatory Medical Care Survey, 2012—Con.

Number of PRFs Percent distribution of PRFs

Census division and state

Expected

from

in-scope

physician

sample1,2 Completed3

Expected

from

in-scope

physician

sample1,2

(weighted)

Completed3

(weighted)

Percent of

expected

PRFs

completed

(weighted)

Pacific

California4 . . . . . . . . . . . . . . . . . . . . . .

Oregon4,5 . . . . . . . . . . . . . . . . . . . . . . .

Washington4 . . . . . . . . . . . . . . . . . . . . .

Remainder states (AK,HI) . . . . . . . . . . . . .

7,686

6,032

4,846

6,367

2,955

1,590

1,960

2,157

13.1

1.5

1.9

0.7

15.1

1.1

2.3

0.7

40.3

26.3

40.6

35.0

1Number of PRFs expected from each physician is the number of visits seen during the physician’s sample week divided by a sampling interval predetermined on the basis of number of days on which
 

the physician expected to see patients and the number of visits expected during that week. When data for deriving expected numbers of PRFs were missing, the number of expected PRFs was
 

imputed as a minimum of 24 (average number of PRFs received from PRF completers in prior years) or the number of visits seen during the sample week.
 

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

3Number of valid completed PRFs received from PRF completers.
 

4Significant difference between weighted percentages of expected and completed PRFs ( p < 0.05).
 

5Percentage of expected PRFs completed is significantly different from total national percentage ( p < 0.05).
 

NOTE: PRF is Patient Record Form.
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
 
Page 24 [ Series 2, No. 171

Table 7. Percent distributions of in-scope sample, numbers of respondents to physician induction interview, and potential bias in

nonresponse-adjusted estimates of percent distributions based on those respondents, by physician characteristic: National Ambulatory

Medical Care Survey, 2012

Physician induction interview respondents

In-scope

sample percent Percent

distribution distribution

using using

calibrated nonresponsePhysician characteristic1 sampling weights2 Number adjusted weights3 Bias4

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 5,622 100.0 . . .

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.4 2,163 39.7 –0.7

50 and over . . . . . . . . . . . . . . . . . . . . . . . . . . 59.6 3,459 60.3 0.7

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.6 4,265 72.3 0.7

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.4 1,357 27.7 –0.7

Census division location of interview

New England . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 347 6.2 0.0

Middle Atlantic. . . . . . . . . . . . . . . . . . . . . . . . . 15.3 469 15.3 0.0

East North Central . . . . . . . . . . . . . . . . . . . . . . 13.0 756 13.0 0.0

West North Central. . . . . . . . . . . . . . . . . . . . . . 5.9 611 5.9 0.0

South Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . 18.8 899 18.8 0.0

East South Central . . . . . . . . . . . . . . . . . . . . . . 5.7 656 5.7 0.0

West South Central . . . . . . . . . . . . . . . . . . . . . 10.6 611 10.6 0.0

Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9 637 6.9 0.0

Pacific. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.5 636 17.5 0.0

Metropolitan status5

MSA6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.7 4,932 92.7 1.0

Non-MSA6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 690 7.3 –1.0

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . . . . . . 94.1 5,310 94.0 –0.1

Doctor of osteopathy. . . . . . . . . . . . . . . . . . . . . 5.9 312 6.0 0.1

Physician specialty7

General or family practice. . . . . . . . . . . . . . . . . . 17.1 803 17.1 0.0

Internal medicine . . . . . . . . . . . . . . . . . . . . . . . 12.8 473 12.8 0.0

Pediatrics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 473 10.3 0.0

General surgery. . . . . . . . . . . . . . . . . . . . . . . . 2.7 244 2.7 0.0

Obstetrics and gynecology . . . . . . . . . . . . . . . . . 7.2 299 7.2 0.0

Orthopedic surgery . . . . . . . . . . . . . . . . . . . . . . 4.5 294 4.5 0.0

Cardiovascular diseases . . . . . . . . . . . . . . . . . . 3.6 210 3.6 0.0

Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 150 2.5 0.0

Urology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 136 1.9 0.0

Psychiatry . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.9 358 5.9 0.0

Neurology . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 138 2.3 0.0

Ophthalmology . . . . . . . . . . . . . . . . . . . . . . . . 3.8 265 3.8 0.0

Otolaryngology . . . . . . . . . . . . . . . . . . . . . . . . 1.9 126 1.9 0.0

Oncology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 213 1.9 0.0

Allergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 219 0.9 0.0

Pulmonology. . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 259 1.8 0.0

All other specialties. . . . . . . . . . . . . . . . . . . . . . 19.0 962 19.0 0.0

Specialty type7

Primary care . . . . . . . . . . . . . . . . . . . . . . . . . . 46.7 2,005 46.8 0.1

Surgical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.7 1,355 20.0 –0.7

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.5 2,262 33.2 0.7

See footnotes at end of table.
Series 2, No. 171 [ Page 25

Table 7. Percent distributions of in-scope sample, numbers of respondents to physician induction interview, and potential bias in

nonresponse-adjusted estimates of percent distributions based on those respondents, by physician characteristic: National Ambulatory

Medical Care Survey, 2012—Con.

Physician induction interview respondents

In-scope

sample percent Percent

distribution distribution

using using

calibrated nonresponsePhysician characteristic1 sampling weights2 Number adjusted weights3 Bias4

Practice type

Solo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.7 1,310 25.4 1.7
 

Two physicians . . . . . . . . . . . . . . . . . . . . . . . . 4.4 261 4.3 –0.1
 

Group or HMO8 . . . . . . . . . . . . . . . . . . . . . . . . 59.4 3,417 58.1 –1.3
 

Medical school or government . . . . . . . . . . . . . . . 1.3 70 1.3 0.0
 

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 57 1.2 0.1
 

Unclassified . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 507 9.8 –0.2
 

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.
 

1Information on characteristics is from the master files of the American Medical Association and the American Osteopathic Association; updated during the survey.
 

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

3Nonresponse adjustments account for physicians who did not complete the induction interview.
 

4Difference between nonresponse-adjusted and total in-scope sample estimates of percentages.
 

5MSA is metropolitan statistical area.
 

6Significant difference between the percentage estimates ( p < 0.05).
 

7Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/
 

Dataset_Documentation/NAMCS/doc2012.pdf).

8HMO is health maintenance organization.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Page 26 [ Series 2, No. 171

Table 8. Percent distributions of in-scope sample, numbers of respondents to physician induction interview, and potential bias in

nonresponse-adjusted estimates of percent distributions based on those respondents, by state location where induction interview

occurred: National Ambulatory Medical Care Survey, 2012

Physician induction interview respondents

In-scope

sample percent Percent

distribution distribution

using using

calibrated Number of nonresponseCensus division and state sampling weights1 respondents adjusted weights Bias2

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 5,622 100.0 . . .

New England

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 150 1.6 0.0

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 133 2.6 –0.1

Remainder states (ME,NH,RI,VT) . . . . . . . . . . . . . . . 1.9 64 2.0 0.1

Middle Atlantic

New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 155 3.9 0.0

New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 165 7.4 0.0

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 149 4.0 0.0

East North Central

Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 176 3.9 0.0

Indiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 185 2.0 0.0

Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 94 2.3 0.0

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 133 3.0 0.0

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 168 1.9 0.0

West North Central

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 160 0.8 0.0

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 129 0.8 0.0

Minnesota. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 121 1.8 –0.1

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 120 1.2 0.0

Remainder states (NE,ND,SD) . . . . . . . . . . . . . . . . . 1.2 81 1.2 0.0

South Atlantic

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 176 7.0 0.0

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 133 2.8 0.0

Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 132 2.2 0.0

North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 105 2.2 0.0

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 89 1.0 0.0

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 153 2.4 0.0

Remainder states (DC,DE,WV). . . . . . . . . . . . . . . . . 1.0 111 1.0 0.0

East South Central

Alabama. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 189 1.4 0.0

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 140 1.2 0.0

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 123 0.7 0.0

Tennessee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 204 2.5 0.0

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 137 0.7 0.0

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 129 1.4 0.0

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 151 0.9 0.0

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 194 7.6 0.0

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 184 1.9 0.0

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 163 1.8 0.0

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 176 0.8 0.0

Remainder states (ID,NM,MT,NV,WY). . . . . . . . . . . . . 2.4 114 2.4 0.0

See footnotes at end of table.
Series 2, No. 171 [ Page 27

Table 8. Percent distributions of in-scope sample, numbers of respondents to physician induction interview, and potential bias in

nonresponse-adjusted estimates of percent distributions based on those respondents, by state location where induction interview

occurred: National Ambulatory Medical Care Survey, 2012—Con.

Physician induction interview respondents

In-scope

sample percent Percent

distribution distribution

using using

calibrated Number of nonresponseCensus division and state sampling weights1 respondents adjusted weights Bias2

Pacific

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3 212 13.3 0.0
 

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 153 1.6 0.0
 

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 118 1.9 0.0
 

Remainder states (AK,HI) . . . . . . . . . . . . . . . . . . . . 0.8 153 0.7 –0.1
 

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.

1In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

2Difference between nonresponse-adjusted and total in-scope sample percentages.
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Page 28 [ Series 2, No. 171

Table 9. Percent distributions of in-scope sample, numbers of physicians completing Patient Record Forms, and potential bias in

nonresponse-adjusted estimates of percent distributions based on Patient Record Form completers, by physician characteristics: National

Ambulatory Medical Care Survey, 2012

PRF completers

In-scope

sample percent Percent

distribution distribution

using using

calibrated nonresponsePhysician characteristic sampling weights1 Number adjusted weights2 Bias3

All office-based physicians . . . . . . . . . . . . . . . . . . . 100.0 3,583 100.0 . . .

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.4 1,360 39.2 –1.2

50 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59.6 2,223 60.8 1.2

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.6 2,750 73.5 1.9

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.4 833 26.5 –1.9

Census division4

New England . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 223 6.2 0.0

Middle Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3 290 15.3 0.0

East North Central . . . . . . . . . . . . . . . . . . . . . . . . 13.0 438 13.0 0.0

West North Central . . . . . . . . . . . . . . . . . . . . . . . . 5.9 398 5.9 0.0

South Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.8 537 18.8 0.0

East South Central . . . . . . . . . . . . . . . . . . . . . . . . 5.7 465 5.7 0.0

West South Central . . . . . . . . . . . . . . . . . . . . . . . 10.6 393 10.6 0.0

Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9 411 6.9 0.0

Pacific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.5 428 17.5 0.0

Metropolitan status5

MSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.7 3,091 92.2 0.5

Non-MSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 492 7.8 –0.5

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . . . . . . . . 94.1 3,378 94.0 –0.1

Doctor of osteopathy . . . . . . . . . . . . . . . . . . . . . . . 5.9 205 6.0 0.1

Physician specialty6

General or family practice . . . . . . . . . . . . . . . . . . . . 17.1 551 17.1 0.0

Internal medicine . . . . . . . . . . . . . . . . . . . . . . . . . 12.8 310 12.8 0.0

Pediatrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 329 10.3 0.0

General surgery . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 153 2.7 0.0

Obstetrics and gynecology . . . . . . . . . . . . . . . . . . . 7.2 188 7.2 0.0

Orthopedic surgery . . . . . . . . . . . . . . . . . . . . . . . . 4.5 182 4.5 0.0

Cardiovascular diseases . . . . . . . . . . . . . . . . . . . . . 3.6 126 3.6 0.0

Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 92 2.5 0.0

Urology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 88 1.9 0.0

Psychiatry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.9 210 5.9 0.0

Neurology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 95 2.3 0.0

Ophthalmology . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8 173 3.8 0.0

Otolaryngology . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 80 1.9 0.0

Oncology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 134 1.9 0.0

Allergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 153 0.9 0.0

Pulmonology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 150 1.8 0.0

All other specialties . . . . . . . . . . . . . . . . . . . . . . . . 19.0 569 19 0.0

Specialty type6

Primary care . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.7 1,353 46.8 0.1

Surgical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.7 839 20.1 –0.6

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.5 1,391 33 0.5

See footnotes at end of table.
Series 2, No. 171 [ Page 29

Table 9. Percent distributions of in-scope sample, numbers of physicians completing Patient Record Forms, and potential bias in

nonresponse-adjusted estimates of percent distributions based on Patient Record Form completers, by physician characteristics: National

Ambulatory Medical Care Survey, 2012—Con.

PRF completers

In-scope

sample percent Percent

distribution distribution

using using

calibrated nonresponsePhysician characteristic sampling weights1 Number adjusted weights2 Bias3

Practice type

Solo7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.7 846 26.7 3.0

Two physicians. . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 179 4.7 0.3

Group or HMO7,8 . . . . . . . . . . . . . . . . . . . . . . . . . 59.4 2,164 56.6 –2.8

Medical school or government . . . . . . . . . . . . . . . . . 1.3 45 1.4 0.1

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 34 0.9 –0.2

Unclassified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 315 9.6 –0.4

Annual visit volume, percentile7

0–25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.0 1,243 33.2 8.2

26–50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.2 736 20.1 –5.1

51–75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.8 577 17.9 –6.9

76–100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.0 1,027 28.8 3.8

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.

1In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

2Nonresponse adjustments account for physicians who did not complete any PRFs because they either were unavailable to see patients during their sample week or refused to complete PRFs.
 

3Difference between nonresponse-adjusted and total in-scope sample estimates of percentages.
 

4Includes state location of office where the most visits were seen.
 

5MSA is metropolitan statistical area.
 

6Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/
 

Dataset_Documentation/NAMCS/doc2012.pdf).
 

7Significant difference between percentage using sampling weight only and nonresponse-adjusted weight ( p < 0.05).
 

8HMO is health maintenance organization.
 

NOTE: PRF is Patient Record Form.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Page 30 [ Series 2, No. 171

Table 10. Percent distributions of in-scope sample, numbers of physicians completing Patient Record Forms, and potential bias in

nonresponse-adjusted estimates of percent distributions based on Patient Record Form completers, by state location of office where the

most visits were seen: National Ambulatory Medical Care Survey, 2012

PRF completers

In-scope

sample percent Percent

distribution distribution

using using

calibrated nonresponse

Census division and state sampling weights1 Number adjusted weights2 Bias3

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 3,583 100.0 . . .

New England

Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 95 1.6 0.0

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 86 2.7 0.0

Remainder states (ME,NH,RI,VT) . . . . . . . . . . . . . . . 1.9 42 1.9 0.0

Middle Atlantic

New Jersey4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 114 4.6 0.7

New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 104 7.7 0.2

Pennsylvania4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 72 3.0 –0.9

East North Central

Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 103 4.1 0.2

Indiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 114 2.2 0.2

Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 60 2.4 0.1

Ohio4

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 63 2.4 –0.6

Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 98 1.9 0.0

West North Central

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 110 0.9 0.1

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 93 0.9 0.1

Minnesota. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 75 1.7 –0.2

Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 72 1.2 0.0

Remainder states (NE,ND,SD) . . . . . . . . . . . . . . . . . 1.2 48 1.2 0.0

South Atlantic

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 106 7.3 0.3

Georgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 89 3.0 0.2

Maryland4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 63 1.8 –0.4

North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 76 2.5 0.2

South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 54 0.9 –0.1

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 90 2.3 –0.1

Remainder states (DC,DE,WV). . . . . . . . . . . . . . . . . 1.0 59 1.0 0.0

East South Central

Alabama. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 132 1.5 0.1

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 88 1.1 –0.2

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 100 0.8 0.1

Tennessee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 145 2.4 0.0

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 76 0.6 –0.1

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 84 1.4 0.0

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 94 0.9 0.0

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 139 7.8 0.2

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 101 1.8 –0.1

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 110 1.9 0.1

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 136 1.0 0.2

Remainder states (ID,NM,MT,NV,WY). . . . . . . . . . . . . 2.4 64 2.2 –0.2

See footnotes at end of table.
Series 2, No. 171 [ Page 31

Table 10. Percent distributions of in-scope sample, numbers of physicians completing Patient Record Forms, and potential bias in

nonresponse-adjusted estimates of percent distributions based on Patient Record Form completers, by state location of office where the

most visits were seen: National Ambulatory Medical Care Survey, 2012—Con.

PRF completers

In-scope

sample percent Percent

distribution distribution

using using

calibrated nonresponse

Census division and state sampling weights1 Number adjusted weights2 Bias3

Pacific

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3 149 13.5 0.2
 

Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 92 1.4 –0.1
 

Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 85 2.0 0.1
 

Remainder states (AK,HI) . . . . . . . . . . . . . . . . . . . . 0.7 102 0.7 0.0
 

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.

1In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and

anesthesiology.

2Nonresponse adjustments account for physicians who did not complete any PRFs because they were either unavailable to see patients during their sample week or did not complete PRFs if they did

see patients in their sample week.
 

3Difference between nonresponse-adjusted and total in-scope sample estimates of percentages.
 

4Significant difference between percentage using sampling weight only and nonresponse-adjusted weight ( p < 0.05).
 

NOTE: PRF is Patient Record Form.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Page 32 [ Series 2, No. 171

Table 11. Estimated percentages of physicians, by selected physician characteristics from the National Electronic Health Record Survey

and the National Ambulatory Medical Care Survey: 2012

2012 NAMCS

2012 NEHRS Induction interview respondents PRF completers

Physician characteristic Percent

Standard

error Percent

Standard

error Bias1 Percent

Standard

error Bias1

All office-based physicians . . . . . . . . . . . . 100.0 . . . 100.0 . . . . . . 100.0 . . . . . .

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . .

50 and over . . . . . . . . . . . . . . . . . . . . .

40.4

59.6

1.2

1.2

39.7

60.3

0.9

0.9

–0.7

0.7

39.2

60.8

1.2

1.2

–1.2

1.2

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . .

Female . . . . . . . . . . . . . . . . . . . . . . . .

70.4

29.6

1.1

1.1

72.3

27.7

0.9

0.9

1.9

–1.9

73.5

26.5

1.1

1.1

3.1

–3.1

Metropolitan status2

MSA3,4 . . . . . . . . . . . . . . . . . . . . . . . .

Non-MSA3,4 . . . . . . . . . . . . . . . . . . . . .

89.3

10.7

0.5

0.5

92.7

7.3

0.4

0.4

3.4

–3.4

92.2

7.8

0.4

0.4

2.9

–2.9

Physician specialty5,6

General or family practice . . . . . . . . . . . . .

Internal medicine . . . . . . . . . . . . . . . . . .

Pediatrics . . . . . . . . . . . . . . . . . . . . . . .

General surgery3,4 . . . . . . . . . . . . . . . . .

Obstetrics and gynecology . . . . . . . . . . . .

Orthopedic surgery . . . . . . . . . . . . . . . . .

Cardiovascular diseases. . . . . . . . . . . . . .

Dermatology . . . . . . . . . . . . . . . . . . . . .

Urology . . . . . . . . . . . . . . . . . . . . . . . .

Psychiatry . . . . . . . . . . . . . . . . . . . . . .

Neurology. . . . . . . . . . . . . . . . . . . . . . .

Ophthalmology. . . . . . . . . . . . . . . . . . . .

Otolaryngology. . . . . . . . . . . . . . . . . . . .

All other specialties3,4 . . . . . . . . . . . . . . .

18.4

11.7

11.2

4.2

7.5

5.1

4.0

2.3

1.9

5.1

2.3

5.1

2.1

19.2

0.9

0.8

0.7

0.5

0.6

0.6

0.5

0.3

0.3

0.5

0.4

0.6

0.3

0.9

17.1

12.8

10.4

2.7

7.3

4.5

3.6

2.5

1.9

5.9

2.3

3.8

1.9

23.2

0.7

0.7

0.6

0.2

0.5

0.3

0.3

0.3

0.2

0.4

0.3

0.3

0.2

0.7

–1.3

1.1

–0.8

–1.5

–0.2

–0.6

–0.4

0.2

0.0

0.8

0.0

–1.3

–0.2

4.0

17.1

12.8

10.5

2.7

7.3

4.5

3.6

2.5

1.9

5.9

2.3

3.8

1.9

23.3

0.8

0.9

0.7

0.3

0.7

0.4

0.4

0.3

0.3

0.6

0.3

0.4

0.3

0.9

–1.3

1.1

–0.7

–1.5

–0.2

–0.6

–0.4

0.2

0.0

0.8

0.0

–1.3

–0.2

4.1

Specialty type5

Primary care . . . . . . . . . . . . . . . . . . . . .

Surgical3,4 . . . . . . . . . . . . . . . . . . . . . .

Medical3,4. . . . . . . . . . . . . . . . . . . . . . .

47.4

23.1

29.6

1.2

1.0

1.1

46.8

20.0

33.2

0.4

0.6

0.7

–0.6

–3.1

3.6

46.8

20.1

33.0

0.5

0.8

0.9

–0.6

–3.0

3.4

Practice size7

Solo3,4. . . . . . . . . . . . . . . . . . . . . . . . .

Partner . . . . . . . . . . . . . . . . . . . . . . . .

3–5 physicians. . . . . . . . . . . . . . . . . . . .

6–10 physicians . . . . . . . . . . . . . . . . . . .

11 or more physicians3,4. . . . . . . . . . . . . .

29.6

9.2

24.8

17.2

19.2

1.1

0.7

1.0

0.9

0.9

36.8

8.4

26.6

15.9

12.4

0.9

0.5

0.8

0.6

0.7

7.2

–0.8

1.8

–1.3

–6.8

36.8

8.8

25.8

16.4

12.1

1.1

0.7

1.0

0.9

0.8

7.2

–0.4

1.0

–0.8

–7.1

Multispecialty status

Solo or single specialty . . . . . . . . . . . . . .

Multispecialty. . . . . . . . . . . . . . . . . . . . .

Unknown . . . . . . . . . . . . . . . . . . . . . . .

75.5

24.5

–

1.0

1.0

–

74.2

23.1

2.7

0.8

0.8

0.3

–1.3

–1.4

. . .

75.5

24.4

*

1.0

1.0

. . .

0.0

–0.1

. . .

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.

– Quantity zero.

* Estimate does not meet standards of reliability or precision.
 

1The difference between the NAMCS and NEHRS estimates for the percentage.
 

2MSA is metropolitan statistical area.
 

3Significant difference between percentage estimates based on NEHRS physicians and NAMCS induction interview respondents ( p < 0.05).
 

4Significant difference between percentage estimates based on NEHRS physicians and NAMCS PRF completers ( p < 0.05).
 

5Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/
 

Dataset_Documentation/NAMCS/doc2012.pdf).
 

6Oncologists, allergists, and pulmonologists are included in various physician specialty categories.
 

7Number of physicians at the location where the physician saw the most visits.
 

NOTE: NEHRS is National Electronic Health Records Survey, NAMCS is National Ambulatory Medical Care Survey, and PRF is Patient Record Form.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012; and National Electronic Health Records Survey, 2012.
Series 2, No. 171 [ Page 33

Table 12. Percent distributions of visits based on in-scope physician sample, numbers of sampled visits, and potential bias in

nonresponse-adjusted estimates of percent distributions of visits, by physician characteristics: National Ambulatory Medical Care

Survey, 2012

Percent distribution Percent distribution

of visits based on of visits based on

in-scope physician sample Number of visit sample

using calibrated sampled using nonresponsePhysician characteristic1,2 sampling weights3,4 visits adjusted weights Bias5

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 76,330 100.0 . . .

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.9 29,837 40.7 –0.2

50 and over . . . . . . . . . . . . . . . . . . . . . . . . . . 59.1 46,493 59.3 0.2

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.6 58,479 73.7 1.1

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.4 17,851 26.3 –1.1

Census division6

New England . . . . . . . . . . . . . . . . . . . . . . . . . 5.6 4,802 5.5 –0.1

Middle Atlantic. . . . . . . . . . . . . . . . . . . . . . . . . 15.0 5,257 14.4 –0.6

East North Central . . . . . . . . . . . . . . . . . . . . . . 12.6 9,564 13 0.4

West North Central. . . . . . . . . . . . . . . . . . . . . . 5.6 9,247 5.4 –0.2

South Atlantic . . . . . . . . . . . . . . . . . . . . . . . . . 20.5 10,840 20.2 –0.3

East South Central . . . . . . . . . . . . . . . . . . . . . . 6.4 8,920 6.6 0.2

West South Central . . . . . . . . . . . . . . . . . . . . . 12.1 9,271 12.8 0.7

Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 9,772 6.7 0.2

Pacific. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7 8,657 15.5 –0.2

Metropolitan status7

MSA8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.1 64,870 89.5 –1.6

Non-MSA8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9 11,460 10.5 1.6

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . . . . . . 93.3 71,607 93.5 0.2

Doctor of osteopathy. . . . . . . . . . . . . . . . . . . . . 6.7 4,723 6.5 –0.2

Physician specialty9

General or family practice. . . . . . . . . . . . . . . . . . 20.5 12,897 20.7 0.2

Internal medicine . . . . . . . . . . . . . . . . . . . . . . . 13.2 6,757 12.7 –0.5

Pediatrics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4 8,751 14 0.6

General surgery. . . . . . . . . . . . . . . . . . . . . . . . 1.6 2,801 1.6 0.0

Obstetrics and gynecology . . . . . . . . . . . . . . . . . 7.7 4,356 7.7 0.0

Orthopedic surgery . . . . . . . . . . . . . . . . . . . . . . 4.7 3,686 5.1 0.4

Cardiovascular diseases . . . . . . . . . . . . . . . . . . 2.9 2,321 2.6 –0.3

Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 2,377 4.2 0.6

Urology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 2,033 1.9 –0.1

Psychiatry . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3,498 3.1 –0.1

Neurology . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 1,805 1.5 –0.3

Ophthalmology . . . . . . . . . . . . . . . . . . . . . . . . 5.0 4,228 4.7 –0.3

Otolaryngology . . . . . . . . . . . . . . . . . . . . . . . . 1.9 1,883 2.1 0.2

Oncology8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 2,585 1.4 –0.4

Allergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 3,394 0.9 0.1

Pulmonology. . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 2,721 1 –0.2

Other specialties . . . . . . . . . . . . . . . . . . . . . . . 14.8 10,237 14.7 –0.1

Specialty type9

Primary care . . . . . . . . . . . . . . . . . . . . . . . . . . 54.1 32,244 54.6 0.5

Surgical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.7 17,354 19.5 –0.2

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.2 26,732 25.9 –0.3

See footnotes at end of table.
Page 34 [ Series 2, No. 171

Table 12. Percent distributions of visits based on in-scope physician sample, numbers of sampled visits, and potential bias in

nonresponse-adjusted estimates of percent distributions of visits, by physician characteristics: National Ambulatory Medical Care

Survey, 2012—Con.

Percent distribution Percent distribution

of visits based on of visits based on

in-scope physician sample Number of visit sample

using calibrated sampled using nonresponsePhysician characteristic1,2 sampling weights3,4 visits adjusted weights Bias5

Practice type

Solo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.2 16,953 24.1 –0.1

Two physicians . . . . . . . . . . . . . . . . . . . . . . . . 4.9 3,946 5.4 0.5

Group or HMO10 . . . . . . . . . . . . . . . . . . . . . . . 59.9 47,939 60.1 0.2

Medical school or government . . . . . . . . . . . . . . . 0.9 716 1.1 0.2

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 689 0.9 –0.2

Unclassified . . . . . . . . . . . . . . . . . . . . . . . . . . 9.0 6,087 8.4 –0.6

Annual visit volume, percentile

0–258 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.9 20,501 18.3 8.4

26–50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.2 15,251 18.6 –1.6

51–758 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.2 14,663 21.3 –5.9

76–100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.7 25,915 41.8 –0.9

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.
 

1Except for annual visit volume, information on characteristics is from the master files of the American Medical Association and the American Osteopathic Association; updated during the survey.
 

2Annual visit volumes for in-scope physicians are estimated as the products of the reported or imputed numbers of visits seen in normal practice weeks and the numbers of weeks in which the
 

physicians typically practice annually.

3In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and

anesthesiology.

4Numerators and the denominator of percentage estimates are weighted sums of estimated annual visit volumes for in-scope sample physicians.

5Difference between nonresponse-adjusted and total in-scope sample estimates of percentages.

6Division visits based on in-scope sample physicians includes state location of office where visit occurred. Division based on visit sample includes state location where visit occurred.

7MSA is metropolitan statistical area.

8Significant difference between percentage using sampling weight only and using nonresponse-adjusted weight ( p < 0.05).

9Physician specialty and specialty type are defined in the 2012 National Ambulatory Medical Care Survey Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/

Dataset_Documentation/NAMCS/doc2012.pdf).

10HMO is health maintenance organization.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Series 2, No. 171 [ Page 35

Table 13. Percent distributions of visits based on in-scope physician sample, numbers of sampled visits, and potential bias in

nonresponse-adjusted estimates of percent distributions of visits, by state location of office where the most visits were seen:

National Ambulatory Medical Care Survey, 2012

Sample visits4

Percent distribution

of visits based on Percent distribution

in-scope physician sample of visits using

using calibrated nonresponseCensus division and state sampling weights1–3 Number adjusted weights Bias5

Total . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 69,528 100.0 . . .

New England

Connecticut6 . . . . . . . . . . . . . . . . . . . . . 1.7 2,121 2.0 0.3

Massachusetts. . . . . . . . . . . . . . . . . . . . 2.5 1,787 2.4 –0.1

Middle Atlantic

New Jersey. . . . . . . . . . . . . . . . . . . . . . 4.3 1,853 4.3 0.0

New York . . . . . . . . . . . . . . . . . . . . . . . 7.4 1,920 7.2 –0.2

Pennsylvania. . . . . . . . . . . . . . . . . . . . . 4.5 1,467 3.7 –0.8

East North Central

Illinois . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 2,297 4.4 0.4

Indiana . . . . . . . . . . . . . . . . . . . . . . . . 2.2 2,630 2.1 –0.1

Michigan . . . . . . . . . . . . . . . . . . . . . . . 2.4 1,203 2.4 0.0

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 1,295 3.2 –0.1

Wisconsin. . . . . . . . . . . . . . . . . . . . . . . 1.7 2,151 1.8 0.1

West North Central

Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 2,857 0.8 –0.1

Kansas . . . . . . . . . . . . . . . . . . . . . . . . 0.9 2,114 0.9 0.0

Minnesota . . . . . . . . . . . . . . . . . . . . . . 1.7 1,598 1.7 0.0

Missouri . . . . . . . . . . . . . . . . . . . . . . . . 1.3 1,654 1.1 –0.2

South Atlantic

Florida. . . . . . . . . . . . . . . . . . . . . . . . . 8.5 1,859 8.1 –0.4

Georgia . . . . . . . . . . . . . . . . . . . . . . . . 3.5 1,844 3.5 0.0

Maryland . . . . . . . . . . . . . . . . . . . . . . . 2.3 1,232 2.5 0.2

North Carolina . . . . . . . . . . . . . . . . . . . . 2.6 1,685 2.5 –0.1

South Carolina. . . . . . . . . . . . . . . . . . . . 1.3 1,272 1.2 –0.1

Virginia . . . . . . . . . . . . . . . . . . . . . . . . 2.7 1,835 2.9 0.2

East South Central

Alabama . . . . . . . . . . . . . . . . . . . . . . . 1.7 2,254 1.8 0.1

Kentucky . . . . . . . . . . . . . . . . . . . . . . . 1.5 1,810 1.5 0.0

Mississippi . . . . . . . . . . . . . . . . . . . . . . 0.8 2,381 0.8 0.0

Tennessee . . . . . . . . . . . . . . . . . . . . . . 2.8 2,460 2.9 0.1

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . . 0.9 1,996 0.8 –0.1

Louisiana . . . . . . . . . . . . . . . . . . . . . . . 1.8 1,747 1.7 –0.1

Oklahoma. . . . . . . . . . . . . . . . . . . . . . . 1.1 2,300 1.2 0.1

Texas . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 3,247 10.0 0.7

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . . 1.9 2,276 2.1 0.2

Colorado . . . . . . . . . . . . . . . . . . . . . . . 1.6 2,366 1.7 0.1

Utah6 . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 3,515 1.0 0.1

See footnotes at end of table.
Page 36 [ Series 2, No. 171

Table 13. Percent distributions of visits based on in-scope physician sample, numbers of sampled visits, and potential bias in

nonresponse-adjusted estimates of percent distributions of visits, by state location of office where the most visits were seen:

National Ambulatory Medical Care Survey, 2012—Con.

Sample visits4

Percent distribution

of visits based on Percent distribution

in-scope physician sample of visits using

using calibrated nonresponseCensus division and state sampling weights1–3 Number adjusted weights Bias5

Pacific

California . . . . . . . . . . . . . . . . . . . . . . . 12.9 2,953 12.8 –0.1
 

Oregon . . . . . . . . . . . . . . . . . . . . . . . . 1.4 1,591 1.3 –0.1
 

Washington. . . . . . . . . . . . . . . . . . . . . . 1.8 1,958 1.7 –0.1
 

. . . Category not applicable.

0.0 Quantity more than zero but less than 0.05.

1In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and

anesthesiology.

2Numerators and the denominator of percentage estimates are weighted sums of estimated annual visit volumes for in-scope sample physicians. Annual visit volumes are estimated as the products of

the reported or imputed numbers of visits seen in normal practice weeks and the numbers of weeks in which the physicians typically practice annually.

3Location of office where the most visits were seen.

4Location of office where visit occurred.

5Difference between nonresponse-adjusted and total in-scope sample estimates of percentages.

6Significant difference between percentage using sampling weight and nonresponse-adjusted weight ( p < 0.05).

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Series 2, No. 171

[ Page 37

Appendix I. Glossary

Annual visit volumes—Estimated as

the products of the reported numbers of

visits the physicians saw during their

last normal weeks of practice, multiplied

by the numbers of weeks they typically

practiced during the year. Questions

about visit numbers and numbers of

weeks were asked of in-scope

physicians during the induction

interview. Missing values for the

numbers of visits in the last normal

week were imputed using linear

regression in the SUDAAN 11 PROC

IMPUTE procedure with independent

variables that were determined through

trial and error to be associated with the

visit volumes reported. The independent

variables used were the physician’s

specialty (19 groups), Census division,

metropolitan statistical area status, age,

race, and (if known) whether the

physician’s largest (in terms of visits

seen) practice is ina multispecialty or

single-specialty office. Other than data

on multi- or single-specialty office

obtained from the induction interview,

the data used for the independent

variables were from the American

Medical Association and the American

Osteopathic Association. Missing

numbers for weeks in which physicians

saw patients annually in their practice

were imputed using averages of those

numbers among the physicians who did

report numbers of practice weeks.

Calibrated sampling weights—The

inverses of sampling probabilities

multiplied by calibration ratios that

adjust the numbers of physicians in the

sampling frame at the time the sample

was selected to the numbers of

physicians eligible for inclusion in that

sampling frame at the time when

NAMCS data were collected.

Division for induction interview

respondents—The Census division

location of the office where the

physician was interviewed.

Division for physician-level

estimates based on Patient Record Form

(PRF) completers—The Census division

location of the office where the

physician saw the most visits during his

or her assigned reporting week, if

known: otherwise, the location where

the physician was interviewed.

NAMCS participating physicians—

Physicians who either completed any

PRF or saw no patients (were

unavailable to see patients) and hence

had no patient visits on which to

complete PRFs during their sample

week due to vacation, conference

attendance, illness, or other reasons.

Physicians with full or adequate

PRF response—Physicians who (a) were

PRF completers who completed PRFs

for 50% or more of their expected

sample visits; or (b) saw no patients

during their sample week. This

definition has been used to define

NAMCS visit-level response rates since

2002.

PRF completers—Physicians with

any completed PRFs (more precisely,

physicians for whom PRFs were

completed by Census field

representatives or by the physician or

office staff).

State for induction interview

respondents—The state location of the

office where the physician was

interviewed.

State for physician-level estimates

based on PRF completers—The state

location of the office where the

physician saw the most visits during his

or her assigned reporting week.
Page 38 [ Series 2, No. 171

Appendix II. NAMCS Estimation Procedures

Physician Estimation

Procedures

The estimator for physician-level

estimates based on physician induction

interview respondents (or physicians

who completed Patient Record Forms

[PRFs]) in the 2012 NAMCS includes

four components:

+	 Inflation by the reciprocal of the

physician’s selection probability.

+	 Adjustment for nonresponse, which

adjusts for in-scope physicians who

did not complete the induction

interview or physicians who did not

complete any PRFs. This adjustment

is done within cells defined by

Census division or targeted state and

physician specialty.

+	 Ratio adjustment within cells defined

by Census division or targeted state

and by physician specialty. This

adjusts the number of physicians in

the sampling frame at the time of

sample selection to known totals for

the frame at the time of the survey.

+	 Weight smoothing.

Visit Estimation

Procedures

The estimator for visit-level

estimates based on completed PRFs for

the 2012 NAMCS includes the

following components:

+	 Inflation by the reciprocals of the

selection probabilities for the

physicians and the visits within

physicians’ practices.

+	 Ratio adjustment (described earlier)

for calibrating physician-level

sampling weights.

+	 Adjustment for nonresponse, which

includes:

C Adjustment for missing PRFs from

PRF completers:

u	 Accounting for visits seen in the

physician’s practice during the

reporting week and for the

number of weeks in a year when

the physician sees patients.

u	 Accounting for missing expected

PRFs:

–	 Within a physician’s practice

for up to one-half of expected

PRFs.

–	 Within cells defined by

physician specialty, Census

division or targeted state, and

metropolitan statistical area

(MSA) status for missing

PRFs in excess of one-half of

PRFs expected from the

practice.

C	 Adjustment for visits to PRF

noncompleters are made within

cells defined by physician

specialty, Census division or

targeted state, and MSA status.

This adjustment used estimated

annual visit volumes, which were

calculated as the products of the

visit volumes for normal practice

weeks and the numbers of weeks

in which the physicians saw

patients annually. When the

weekly visit volumes needed in

these annual visit volume

calculations were missing, they

were imputed (as described earlier

in Methods).

+	 Weight smoothing.
Series 2, No. 171 [ Page 39

Appendix III. Physicians With Full or Adequate Response to Patient

Record Forms

If data were gathered for one or

more visits but fewer than one-half of

the expected number of sample visits

from a physician’s reporting week, the

physician was considered to be a

minimal responder at the visit level. Of

the 3,583 physicians who were Patient

Record Form (PRF) completers, 3,010

participated fully (submitted at least

one-half of the PRFs expected from

their practices, based on the total

number of visits during their reporting

weeks), and 573 participated minimally

(submitted fewer than one-half of the

expected numbers of PRFs for their

reporting weeks). Physicians are

considered full PRF respondents if they

either completed PRF data for at least

one-half of their expected numbers of

sampled visits or saw no patients during

their sample week. By this measure,

physicians who saw patients but

completed no PRFs, as well as

physicians who participated minimally,

were considered nonrespondents at the

visit level. In 2012, the percentage of

physicians with full response to PRF

visit data was 39.3%, unweighted

(39.4% weighted).

Comparison of weighted (using

calibrated sampling weights only)

percent distributions of full PRF

responders and nonresponders by

physician characteristics (Table I)

indicates that the distributions did not

differ by physician age, sex, type of

doctor (M.D. or D.O.), specialty type, or

practice type. However, distributions of

respondents and nonrespondents differed

by Census division, metropolitan

statistical area (MSA) status, physician

specialty, annual visit volume, and state.

Table I. In-scope sample physicians, their weighted percent distributions by Patient Record Form response status, and Patient Record Form

response rate, by physician characteristics: United States, 2012

In-scope Full or adequate PRF response status (weighted)

Number of sample

in-scope percent Percent Percent Response

sample distribution distribution of distribution of rate6

Physician characteristic1 physicians2,3 (weighted) respondents4 nonrespondents5 (weighted)

All office-based physicians . . . . . . . . . . . . 9,574 100.0 100.0 100.0 39.4

Age

Under 50 . . . . . . . . . . . . . . . . . . . . . . . 3,741 40.4 40.4 40.4 39.4

50 and over . . . . . . . . . . . . . . . . . . . . . 5,833 59.6 59.6 59.6 39.3

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . . 7,239 71.6 70.8 72.1 38.9

Female . . . . . . . . . . . . . . . . . . . . . . . . 2,335 28.4 29.2 27.9 40.5

Census division7

New England. . . . . . . . . . . . . . . . . . . . . 684 6.2 5.8 6.4 37.0

Middle Atlantic8 . . . . . . . . . . . . . . . . . . . 811 15.3 13.6 16.4 34.9

East North Central . . . . . . . . . . . . . . . . . 1,166 13.0 14.0 12.4 42.2

West North Central . . . . . . . . . . . . . . . . . 1,067 5.9 6.4 5.6 42.5

South Atlantic8 . . . . . . . . . . . . . . . . . . . . 1,593 18.8 17.2 19.8 35.9

East South Central . . . . . . . . . . . . . . . . . 1,092 5.7 5.6 5.8 38.6

West South Central . . . . . . . . . . . . . . . . 1,040 10.6 10.9 10.5 40.2

Mountain . . . . . . . . . . . . . . . . . . . . . . . 1,017 6.9 7.6 6.5 43.1

Pacific . . . . . . . . . . . . . . . . . . . . . . . . 1,104 17.5 19.0 16.5 42.7

Metropolitan status7,9

MSA . . . . . . . . . . . . . . . . . . . . . . . . . . 8,473 91.7 90.8 92.3 39.0

Non-MSA8 . . . . . . . . . . . . . . . . . . . . . . 1,101 8.3 9.2 7.7 43.8

Type of doctor

Doctor of medicine . . . . . . . . . . . . . . . . . 9,083 94.1 94.0 94.3 39.3

Doctor of osteopathy . . . . . . . . . . . . . . . . 491 5.9 6.0 5.7 40.5

Physician specialty7,10

General or family practice . . . . . . . . . . . . . 1,265 17.1 17.8 16.7 40.9

Internal medicine8. . . . . . . . . . . . . . . . . . 811 12.8 11.2 13.9 34.3

Pediatrics8 . . . . . . . . . . . . . . . . . . . . . . 688 10.3 13.2 8.4 50.6

General surgery . . . . . . . . . . . . . . . . . . . 391 2.7 2.9 2.6 42.2

Obstetrics and gynecology . . . . . . . . . . . . 509 7.2 6.9 7.5 37.4

See footnotes at end of table.
Page 40 [ Series 2, No. 171

Table I. In-scope sample physicians, their weighted percent distributions by Patient Record Form response status, and Patient Record Form

response rate, by physician characteristics: United States, 2012—Con.

In-scope Full or adequate PRF response status (weighted)

Number of sample

in-scope percent Percent Percent Response

sample distribution distribution of distribution of rate6

Physician characteristic1 physicians2,3 (weighted) respondents4 nonrespondents5 (weighted)

Physician specialty7,10—Con.

Orthopedic surgery . . . . . . . . . . . . . . . . . 555 4.5 4.0 4.8 35.1

Cardiovascular diseases. . . . . . . . . . . . . . 416 3.6 3.4 3.8 36.7

Dermatology . . . . . . . . . . . . . . . . . . . . . 260 2.5 2.7 2.3 42.8

Urology . . . . . . . . . . . . . . . . . . . . . . . . 243 1.9 1.8 1.9 37.5

Psychiatry . . . . . . . . . . . . . . . . . . . . . . 597 5.9 5.8 6.0 38.3

Neurology. . . . . . . . . . . . . . . . . . . . . . . 232 2.3 2.5 2.1 43.8

Ophthalmology. . . . . . . . . . . . . . . . . . . . 448 3.8 3.8 3.8 39.2

Otolaryngology. . . . . . . . . . . . . . . . . . . . 220 1.9 1.7 2.0 35.5

Oncology8 . . . . . . . . . . . . . . . . . . . . . . 416 1.9 1.4 2.2 30.1

Allergy. . . . . . . . . . . . . . . . . . . . . . . . . 398 0.9 0.9 0.8 43.7

Pulmonology . . . . . . . . . . . . . . . . . . . . . 420 1.8 1.9 1.7 43.1

All other specialties . . . . . . . . . . . . . . . . . 1,705 19.0 18.1 19.6 37.5

Specialty type10

Primary care . . . . . . . . . . . . . . . . . . . . . 3,204 46.7 48.2 45.8 40.6

Surgical . . . . . . . . . . . . . . . . . . . . . . . . 2,411 20.7 19.5 21.5 37.1

Medical . . . . . . . . . . . . . . . . . . . . . . . . 3,959 32.5 32.3 32.7 39.0

Practice type

Solo . . . . . . . . . . . . . . . . . . . . . . . . . . 2,089 23.7 24.6 23.2 40.8

Two physicians . . . . . . . . . . . . . . . . . . . 426 4.4 4.2 4.5 37.7

Group or HMO11 . . . . . . . . . . . . . . . . . . 5,993 59.4 58.6 60.0 38.8

Medical school or government . . . . . . . . . . 116 1.3 1.3 1.3 40.6

Other . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.1 1.3 1.0 47.4

Unclassified . . . . . . . . . . . . . . . . . . . . . 862 10.0 9.9 10.1 39.0

Annual visit volume, percentile7

0–25 . . . . . . . . . . . . . . . . . . . . . . . . . . 2,607 25.0 34.7 18.8 54.5

26–50 . . . . . . . . . . . . . . . . . . . . . . . . . 2,574 25.2 20.6 28.1 32.2

51–75 . . . . . . . . . . . . . . . . . . . . . . . . . 2,155 24.8 17.9 29.3 28.3

76–100 . . . . . . . . . . . . . . . . . . . . . . . . 2,238 25.0 26.9 23.8 42.3

1Information on characteristics is from the master files of the American Medical Association and the American Osteopathic Association; updated during the survey.

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and

anesthesiology.

3Physicians who were selected to the 2012 NAMCS sample and confirmed, during the survey, to be in-scope.

4Responding physicians are those who were in-scope and participated fully or adequately in completion of PRFs or were unavailable to complete PRFs.

5Nonresponding physicians are those who were in-scope and participated minimally or refused to participate in NAMCS.

6Values represent a response rate among physicians selected to the office-based sample. Numerator is the number of in-scope physicians to the physician sample who participated fully or adequately

in NAMCS or who did not see any patients during their sampled reporting week. Denominator is all in-scope physicians selected to the physician sample.

7Chi-square test of association is significant (p < 0.05) between physician response and indicated physician characteristic.

8Response rate is significantly different from national rate (p < 0.05).

9MSA is metropolitan statistical area.

10Physician specialty and specialty type defined in the 2012 NAMCS Public Use Data File Documentation (see ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NAMCS/

doc2012.pdf).

11HMO health maintenance organization.

NOTE: PRF is Patient Record Form and NAMCS is National Ambulatory Medical Care Survey.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
Series 2, No. 171 [ Page 41

Rates of full PRF response among higher than the national rate. Full Missouri (47.1%), and Utah (58.5%).

physicians in the Middle Atlantic response among internists (34.3%) and Response rates were lower than for the

(34.9%) and South Atlantic (35.9%) oncologists (30.1%), however, was nation in New Jersey (33.3%), Florida,

divisions were lower than the national lower than the national rate. (33.4%), Maryland (31.5%), and

rate (39.4%). Full response among Among states, rates of full PRF Louisiana (31.1%) (Table II).

physicians outside of MSAs (40.5%) response were higher than for the nation

and among pediatricians (50.6%) was in Indiana (47.6%), Iowa (48.1%),

Table II. In-scope sample physicians, their weighted percent distributions by Patient Record Form response status, and Patient Record

Form response rate, by state location of office where the most visits were seen: United States, 2012

In-scope Full or adequate PRF response status (weighted)

Number of sample

in-scope percent Percent Percent Response

sample distribution distribution of distribution of rate6

Census division and state1 physicians2,3 (weighted) respondents4 nonrespondents5 (weighted)

Total . . . . . . . . . . . . . . . . . . . . . . . . . . 9,574 100.0 100.0 100.0 39.4

New England

Connecticut. . . . . . . . . . . . . . . . . . . . . . 276 1.6 1.7 1.6 40.2

Massachusetts. . . . . . . . . . . . . . . . . . . . 249 2.7 2.7 2.6 40.1

Remainder states (ME,NH,RI,VT)7 . . . . . . . 159 1.9 1.4 2.2 30.0

Middle Atlantic

New Jersey7 . . . . . . . . . . . . . . . . . . . . . 291 3.9 3.3 4.3 33.3

New York . . . . . . . . . . . . . . . . . . . . . . . 287 7.5 7.0 7.8 36.7

Pennsylvania. . . . . . . . . . . . . . . . . . . . . 233 3.9 3.3 4.3 33.3

East North Central

Illinois . . . . . . . . . . . . . . . . . . . . . . . . . 264 3.9 4.0 3.9 40.2

Indiana7 . . . . . . . . . . . . . . . . . . . . . . . . 274 2.0 2.4 1.7 47.6

Michigan . . . . . . . . . . . . . . . . . . . . . . . 175 2.3 2.6 2.1 44.3

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . 210 3.0 2.9 3.0 38.4

Wisconsin. . . . . . . . . . . . . . . . . . . . . . . 243 1.9 2.1 1.7 44.3

West North Central

Iowa7 . . . . . . . . . . . . . . . . . . . . . . . . . 263 0.8 1.0 0.7 48.1

Kansas . . . . . . . . . . . . . . . . . . . . . . . . 232 0.8 0.9 0.7 46.2

Minnesota . . . . . . . . . . . . . . . . . . . . . . 262 1.9 1.6 2.0 34.7

Missouri7 . . . . . . . . . . . . . . . . . . . . . . . 188 1.2 1.4 1.0 47.1

Remainder states (NE,ND,SD) . . . . . . . . . . 122 1.2 1.4 1.1 43.7

South Atlantic

Florida7 . . . . . . . . . . . . . . . . . . . . . . . . 304 7.0 6.0 7.7 33.4

Georgia . . . . . . . . . . . . . . . . . . . . . . . . 255 2.8 2.7 2.9 38.0

Maryland7

. . . . . . . . . . . . . . . . . . . . . . . 226 2.2 1.7 2.5 31.5

North Carolina . . . . . . . . . . . . . . . . . . . . 199 2.3 2.3 2.2 40.9

South Carolina. . . . . . . . . . . . . . . . . . . . 187 1.0 0.9 1.1 35.5

Virginia . . . . . . . . . . . . . . . . . . . . . . . . 234 2.4 2.5 2.4 40.7

Remainder states (DC,DE,WV) . . . . . . . . . 188 1.0 0.9 1.1 35.3

East South Central

Alabama . . . . . . . . . . . . . . . . . . . . . . . 265 1.4 1.3 1.4 39.3

Kentucky . . . . . . . . . . . . . . . . . . . . . . . 253 1.3 1.1 1.3 35.7

Mississippi . . . . . . . . . . . . . . . . . . . . . . 252 0.7 0.7 0.7 39.7

Tennessee . . . . . . . . . . . . . . . . . . . . . . 322 2.4 2.5 2.4 39.4

West South Central

Arkansas . . . . . . . . . . . . . . . . . . . . . . . 226 0.7 0.7 0.7 39.2

Louisiana7 . . . . . . . . . . . . . . . . . . . . . . 251 1.4 1.1 1.6 31.1

Oklahoma. . . . . . . . . . . . . . . . . . . . . . . 221 0.9 1.0 0.8 44.0

Texas . . . . . . . . . . . . . . . . . . . . . . . . . 342 7.6 8.0 7.3 41.6

See footnotes at end of table.
Page 42 [ Series 2, No. 171

Table II. In-scope sample physicians, their weighted percent distributions by Patient Record Form response status, and Patient Record

Form response rate, by state location of office where the most visits were seen: United States, 2012—Con.

In-scope Full or adequate PRF response status (weighted)

Number of sample

in-scope percent Percent Percent Response

sample distribution distribution of distribution of rate6

Census division and state1 physicians2,3 (weighted) respondents4 nonrespondents5 (weighted)

Mountain

Arizona . . . . . . . . . . . . . . . . . . . . . . . . 277 1.9 2.1 1.8 42.4

Colorado . . . . . . . . . . . . . . . . . . . . . . . 271 1.8 2.0 1.7 44.0

Utah7 . . . . . . . . . . . . . . . . . . . . . . . . . 257 0.8 1.2 0.5 58.5

Remainder states (ID,NM,MT,NV,WY) . . . . . 212 2.4 2.3 2.4 37.9

Pacific

California . . . . . . . . . . . . . . . . . . . . . . . 346 13.3 14.9 12.3 44.1

Oregon . . . . . . . . . . . . . . . . . . . . . . . . 269 1.5 1.3 1.7 33.6

Washington. . . . . . . . . . . . . . . . . . . . . . 215 1.9 2.1 1.8 42.0

Remainder states (AK,HI) . . . . . . . . . . . . . 274 0.7 0.8 0.7 40.1

1Chi-square test of association is significant (p < 0.05) between physician response and state location of office where the most visits were seen.
 

2In-scope sample physicians are those confirmed during the survey to be nonfederal and involved in direct patient care in an office-based practice, excluding the specialties of radiology, pathology, and
 

anesthesiology.
 

3Physicians who were selected to the 2012 NAMCS sample and confirmed, during the survey, to be in-scope.
 

4Responding physicians are those who were in-scope and participated fully or adequately in completion of PRFs or were unavailable to complete PRFs.
 

5Nonresponding physicians are those who were in-scope and participated minimally or refused to participate in NAMCS.
 

6Values represent a response rate among physicians selected to the office-based sample. Numerator is the number of in-scope physicians from the physician sample who participated fully or
 

adequatelyly in NAMCS or who did not see any patients during their sampled reporting week. Denominator is all in-scope physicians selected to the physician sample.
 

7State response rate is significantly different from total national rate (p < 0.05).
 

NOTE: PRF is Patient Record Form and NAMCS is National Ambulatory Medical Care Survey.
 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, 2012.
 
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