yyyyy zzzz {{{{{ |||| Report 5

Estimation Procedures in the 1996 

Medical Expenditure Panel Survey 

Household Component 

Methodology Methodology 

U.S. Department of Health and Human Services

Public Health Service

Agency for Health Care Policy and Research

Agency for Health Care Policy and Research
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Abstract

The Medical Expenditure Panel Survey (MEPS) is

the third in a series of nationally representative surveys

of medical care use and expenditures sponsored by the

Agency for Health Care Policy and Research (AHCPR).

MEPS comprises four component surveys. The

Household Component (HC) produces national and

regional estimates of the health care utilization,

expenditures, sources of payment, and insurance

coverage of the U.S. civilian noninstitutionalized

population. The HC sample design is a stratified

multistage area probability design with disproportionate

sampling to facilitate the selection of an oversample of

minorities. This report provides an overall summary of

HC sample yields across the three rounds of data

collection that cover calendar year 1996. It also provides

an overview of the weighting strategies used to obtain

national estimates of health care parameters for the

population. Survey design complexities that require

special consideration for variance estimation and analysis

are discussed.

Suggested citation

Cohen SB, DiGaetano R, Goksel H. Estimation procedures in the

1996 Medical Expenditure Panel Survey Household Component.

Rockville (MD):Agency for Health Care Policy and Research; 1999.

MEPS Methodology Report No. 5. AHCPR Pub. No. 99-0027.

http://www.ahcpr.gov/ http://www.ahcpr.gov/
Estimation Procedures in the 1996 

Medical Expenditure Panel Survey 

Household Component 

U.S. Department of Health and Human Services

Public Health Service

Agency for Health Care Policy and Research

   yyyyy zzzz {{{{{ |||| Report 5

Methodology Methodology 

AHCPR Pub. No. 99-0027

May 1999
The Medical Expenditure Panel

Survey (MEPS)

Background

The Medical Expenditure Panel Survey (MEPS) is

conducted to provide nationally representative estimates

of health care use, expenditures, sources of payment,

and insurance coverage for the U.S. civilian

noninstitutionalized population. MEPS also includes a

nationally representative survey of nursing homes and

their residents. MEPS is cosponsored by the Agency for

Health Care Policy and Research (AHCPR) and the

National Center for Health Statistics (NCHS).

MEPS comprises four component surveys: the

Household Component (HC), the Medical Provider

Component (MPC), the Insurance Component (IC), and

the Nursing Home Component (NHC). The HC is the

core survey, and it forms the basis for the MPC sample

and part of the IC sample. The separate NHC sample

supplements the other MEPS components. Together

these surveys yield comprehensive data that provide

national estimates of the level and distribution of health

care use and expenditures, support health services

research, and can be used to assess health care policy

implications.

MEPS is the third in a series of national probability

surveys conducted by AHCPR on the financing and use

of medical care in the United States. The National

Medical Care Expenditure Survey (NMCES) was

conducted in 1977, the National Medical Expenditure

Survey (NMES) in 1987. Beginning in 1996, MEPS

continues this series with design enhancements and

efficiencies that provide a more current data resource to

capture the changing dynamics of the health care

delivery and insurance system.

The design efficiencies incorporated into MEPS are

in accordance with the Department of Health and

Human Services (DHHS) Survey Integration Plan of

June 1995, which focused on consolidating DHHS

surveys, achieving cost efficiencies, reducing respondent

burden, and enhancing analytical capacities. To

accommodate these goals, new MEPS design features

include linkage with the National Health Interview

Survey (NHIS), from which the sample for the MEPS

HC is drawn, and enhanced longitudinal data collection

for core survey components. The MEPS HC augments

NHIS by selecting a sample of NHIS respondents,

collecting additional data on their health care

expenditures, and linking these data with additional

information collected from the respondents’ medical

providers, employers, and insurance providers.

Household Component

The MEPS HC, a nationally representative survey

of the U.S. civilian noninstitutionalized population,

collects medical expenditure data at both the person and

household levels. The HC collects detailed data on

demographic characteristics, health conditions, health

status, use of medical care services, charges and

payments, access to care, satisfaction with care, health

insurance coverage, income, and employment.

The HC uses an overlapping panel design in which

data are collected through a preliminary contact

followed by a series of five rounds of interviews over a 

21⁄

2-year period. Using computer-assisted personal

interviewing (CAPI) technology, data on medical

expenditures and use for 2 calendar years are collected

from each household. This series of data collection

rounds is launched each subsequent year on a new

sample of households to provide overlapping panels of

survey data and, when combined with other ongoing

panels, will provide continuous and current estimates of

health care expenditures.

The sampling frame for the MEPS HC is drawn

from respondents to NHIS, conducted by NCHS. NHIS

provides a nationally representative sample of the U.S.

civilian noninstitutionalized population, with

oversampling of Hispanics and blacks.

Medical Provider Component

The MEPS MPC supplements and validates

information on medical care events reported in the

MEPS HC by contacting medical providers and

pharmacies identified by household respondents. The

MPC sample includes all hospitals, hospital physicians,

home health agencies, and pharmacies reported in the

ii
iii

HC. Also included in the MPC are all office-based

physicians: 

• Providing care for HC respondents receiving

Medicaid.

• Associated with a 75-percent sample of households

receiving care through an HMO (health maintenance

organization) or managed care plan.

• Associated with a 25-percent sample of the

remaining households.

Data are collected on medical and financial

characteristics of medical and pharmacy events reported

by HC respondents, including:

• Diagnoses coded according to ICD-9 (9th Revision,

International Classification of Diseases) and DSMIV (Fourth Edition, Diagnostic and Statistical

Manual of Mental Disorders).

• Physician procedure codes classified by CPT-4

(Current Procedural Terminology, Version 4).

• Inpatient stay codes classified by DRG (diagnosisrelated group).

• Prescriptions coded by national drug code (NDC),

medication names, strength, and quantity dispensed.

• Charges, payments, and the reasons for any

difference between charges and payments.

The MPC is conducted through telephone

interviews and mailed survey materials.

Insurance Component

The MEPS IC collects data on health insurance

plans obtained through employers, unions, and other

sources of private health insurance. Data obtained in the

IC include the number and types of private insurance

plans offered, benefits associated with these plans,

premiums, contributions by employers and employees,

and employer characteristics.

Establishments participating in the MEPS IC are

selected through four sampling frames:

• A list of employers or other insurance providers

identified by MEPS HC respondents who report

having private health insurance at the Round 1

interview.

• A Bureau of the Census list frame of private-sector

business establishments.

• The Census of Governments from the Bureau of the

Census.

• An Internal Revenue Service list of the selfemployed.

To provide an integrated picture of health insurance,

data collected from the first sampling frame (employers

and other insurance providers) are linked back to data

provided by the MEPS HC respondents. Data from the

other three sampling frames are collected to provide

annual national and State estimates of the supply of

private health insurance available to American workers

and to evaluate policy issues pertaining to health

insurance.

The MEPS IC is an annual panel survey. Data are

collected from the selected organizations through a

prescreening telephone interview, a mailed

questionnaire, and a telephone followup for

nonrespondents.

Nursing Home Component

The 1996 MEPS NHC was a survey of nursing

homes and persons residing in or admitted to nursing

homes at any time during calendar year 1996. The NHC

gathered information on the demographic

characteristics, residence history, health and functional

status, use of services, use of prescription medications,

and health care expenditures of nursing home residents.

Nursing home administrators and designated staff also

provided information on facility size, ownership,

certification status, services provided, revenues and

expenses, and other facility characteristics. Data on the

income, assets, family relationships, and caregiving

services for sampled nursing home residents were

obtained from next-of-kin or other knowledgeable

persons in the community.

The 1996 MEPS NHC sample was selected using a

two-stage stratified probability design. In the first stage,

facilities were selected; in the second stage, facility

residents were sampled, selecting both persons in

residence on January 1, 1996, and those admitted during

the period January 1 through December 31.

The sampling frame for facilities was derived from

the National Health Provider Inventory, which is

updated periodically by NCHS. The MEPS NHC data

were collected in person in three rounds of data

collection over a 11⁄

2-year period using the CAPI system.

Community data were collected by telephone using

computer-assisted telephone interviewing (CATI)

technology. At the end of three rounds of data collection,
iv













































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|||| the sample consisted of 815 responding facilities, 3,209

residents in the facility on January 1, and 2,690 eligible

residents admitted during 1996.

Survey Management

MEPS data are collected under the authority of the

Public Health Service Act. They are edited and

published in accordance with the confidentiality

provisions of this act and the Privacy Act. NCHS

provides consultation and technical assistance.

As soon as data collection and editing are

completed, the MEPS survey data are released to the

public in staged releases of summary reports and

microdata files. Summary reports are released as printed

documents and electronic files. Microdata files are

released on CD-ROM and/or as electronic files.

Printed documents and CD-ROMs are available

through the AHCPR Publications Clearinghouse. Write

or call:

AHCPR Publications Clearinghouse

Attn: (publication number)

P.O. Box 8547

Silver Spring, MD 20907

800-358-9295

410-381-3150 (callers outside the United States

only)

888-586-6340 (toll-free TDD service; hearing

impaired only)

Be sure to specify the AHCPR number of the

document or CD-ROM you are requesting. Selected

electronic files are available through the Internet on the

AHCPR Web site: 

http://www.ahcpr.gov/

On the AHCPR Web site, under Data and Surveys, 

click the MEPS icon.

Additional information on MEPS is available from

the MEPS project manager or the MEPS public use data

manager at the Center for Cost and Financing Studies,

Agency for Health Care Policy and Research, 2101 East

Jefferson Street, Suite 500, Rockville, MD 20852 

(301-594-3075).
v

Table of Contents

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

MEPS Household Component Sample Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Round 1 Field Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Sampling Weight Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Variance Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Tables

1. Response rates for the 1996 MEPS Household Component, Round 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2. Population estimates by sex and age for December 1996 and March 1997: United States. . . . . . . . . . . . 14
1

Introduction

The 1996 Medical Expenditure Panel Survey

(MEPS) Household Component (HC) was designed to

produce national and regional estimates of the health

care utilization, expenditures, sources of payment, and

insurance coverage of the U.S. civilian

noninstitutionalized population for calendar year 1996.

MEPS includes surveys of medical providers, employers,

and other health insurance providers to supplement the

data provided by household respondents. The design of

MEPS permits both person-based and family-level

estimates. Government agencies, legislative bodies, and

health professionals need comprehensive national

estimates in order to formulate and analyze national

health policies. The scope and depth of this data

collection effort address that need.

MEPS is the third in a series of national probability

surveys conducted by the Agency for Health Care Policy

and Research (AHCPR) on the financing and utilization

of medical care in the United States. Previous surveys

were the 1977 National Medical Care Expenditure

Survey (NMCES) and the 1987 National Medical

Expenditure Survey (NMES).

The MEPS HC is an ongoing annual survey, with

each sample panel collecting data over a 30-month

period to obtain information that covers two consecutive

calendar years. MEPS collects data on the specific

health services that Americans use, how frequently they

use them, the cost of these services, and how they are

paid for. MEPS also collects data on the cost, scope, and

breadth of private health insurance held by and available

to the U.S. population. MEPS is unparalleled for the

degree of detail in its data, as well as its ability to link

medical expenditures and health insurance data to survey

respondents’ demographic, employment, economic,

health status, utilization of health services, and other

characteristics. Moreover, MEPS is the only federally

sponsored national survey that provides a foundation for

estimating the impact of changes in sources of payment

and insurance coverage on different economic groups or

special populations of interest, such as the poor, elderly,

families, veterans, the uninsured, and racial and ethnic

minorities.

The survey is cosponsored by AHCPR and the

National Center for Health Statistics (NCHS). Westat,

Inc., and the National Opinion Research Center (NORC)

are the data collection organizations for the 1996 MEPS

HC.

The MEPS HC sample design is a stratified

multistage area probability design with disproportionate

sampling to facilitate the selection of an oversample of

minorities (Cohen SB, 1997a). This report provides an

overall summary of sample yields across the three

rounds of data collection that cover calendar year 1996.

It also provides an overview of the weighting strategies

adopted to obtain national estimates of health care

parameters for the U.S. civilian noninstitutionalized

population. In addition, survey design complexities that

require special consideration for variance estimation and

analysis are discussed.

MEPS Household Component

Sample Design

The set of households selected for the 1996 MEPS

is a subsample of those participating in the National

Health Interview Survey (NHIS). NHIS is an ongoing

annual household survey of approximately 42,000

households (109,000 individuals). NCHS conducts

NHIS to obtain national estimates for the U.S. civilian

noninstitutionalized population on health care utilization,

health conditions, health status, insurance coverage, and

access. In addition to the cost savings achieved by

eliminating the need to list and screen households

independently, selecting a subsample of NHIS

participants for MEPS has resulted in survey data with

enhanced analytical capacity. Use of the 1995 NHIS data

in concert with the data collected for the 1996 MEPS

provides the capacity for longitudinal analyses not

Estimation Procedures in the 1996 Medical Expenditure Panel Survey

Household Component

by Steven B. Cohen, Ph.D.,Agency for Health Care Policy and Research, and Ralph DiGaetano, M.S., and

Huseyin Goksel, M.S.,Westat, Inc.
2

otherwise available. Furthermore, the greater number

and dispersion of the primary sampling units (PSUs)

that compose the MEPS national sample have resulted

in improvements in precision over previous expenditure

survey designs (Arnett, Hunter, Cohen, et al., 1996;

Cohen SB, 1996). 

The MEPS HC consists of an overlapping panel

design in which each sample panel is interviewed a total

of five times over 30 months to yield annual use and

expenditure data for two calendar years. Design

specifications for the 1996 MEPS required that the full

series of interviews necessary to acquire information for

calendar year 1996 be completed in approximately

9,000 households. The same panel of households was

interviewed in person three times over the course of the

survey to obtain data on members’ health care

experience for 1996 (Cohen JW, 1997).

The 1996 MEPS HC sample was selected from

households that responded to the 1995 NHIS. More

specifically, the 1996 MEPS HC sample was selected

from a nationally representative NHIS subsample from

two out of four NHIS panels to represent the Nation. It

encompassed half of the participating households in the

NHIS sample during the second and third quarters of

1995. NHIS was designed to permit nationally

representative subsamples to be selected by restricting

the sample to one of four distinct panels. Any

combination of one to four panels will provide a

nationally representative sample of households.

Furthermore, each NHIS panel subsample for a given

quarter of a calendar year is nationally representative.

The complete 1995 NHIS sample (panels 1-4)

consists of 358 PSUs (i.e., counties or groups of

contiguous counties) with a targeted sample of

approximately 42,000 responding households. The

sample PSUs selected for NHIS were stratified by

geographic area (Census region and State), metropolitan

statistical area (MSA), and sociodemographic measures

(Judkins, Marker, and Waksberg, 1994). In order to

oversample areas with high population concentrations of

blacks and Hispanics, a sample of blocks (segments)

was selected within sample PSUs after being stratified

by measures of minority population density. A

nationally representative sample of approximately

71,000 addresses within sampled blocks was selected

and targeted for further screening to include an

oversampling of households containing blacks and

Hispanics as part of the 1995 NHIS interview. 

The nationally representative 1995 NHIS subsample

selected for the 1996 MEPS consists of 195 PSUs. In

the two targeted quarters of 1995, these PSUs included

1,675 sample segments (second-stage sampling units)

and 10,597 households responding to NHIS. This NHIS

sample reflects an oversampling of households with

Hispanics and blacks at the following approximate

ratios of representation relative to the remaining

households: Hispanics, 2.0:1.0; blacks, 1.5:1.0. The

sample size for the 1996 MEPS was targeted at

approximately 9,000 reporting units (generally, families

or single persons) yielding the complete series of core

interviews (i.e., Rounds 1-3) to obtain health care use

and expenditure data for calendar year 1996.

Procedures for Data Collection

Five in-person interviews were conducted with each

NHIS panel selected for the MEPS HC at 3- to 4-month

intervals over an approximately 30-month field period.

The first three of these rounds (Rounds 1-3) of the 1996

MEPS HC served to collect the main body of utilization

and expenditure data for calendar year 1996. Rounds 3-

5 for the 1996 MEPS panel cover 1997. Rounds 3-5 will

be combined with Rounds 1-3 of the 1997 MEPS panel

to yield the full sample base for the 1997 MEPS HC

and be the source of annual estimates for that calendar

year.

All interviews were conducted in person, using a

computer-assisted personal interview (CAPI) as the

principal data collection mode. Round 1 asks about the

period from January 1 of the calendar year to the date of

that interview; Round 2 asks about the time from the

Round 1 interview through the date of the Round 2

interview; and Round 3 collects data from the date of

the Round 2 interview in 1996 through the date of the

Round 3 interview in 1997. Thus, Round 3 covers both

calendar years, and the data are partitioned accordingly

for estimation purposes.

Sampling Unit Definitions

The definitions of dwelling units and group quarters

in the MEPS HC are generally consistent with the

definitions used for NHIS. While the MEPS sample is a

subsample of NHIS dwelling units (referred to as

households), a reporting unit for MEPS data collection
3

purposes was defined as a person or group of persons in

a sampled dwelling unit who are related by blood,

marriage, adoption, or other family associations. All

persons in a sampled reporting unit were to be

interviewed at the same time. When unrelated persons

lived in the same dwelling unit, sample households were

split into multiple reporting units. Examples of the

relationship between sample dwelling units and

corresponding reporting units include the following:

• A married daughter and her husband living in the

same dwelling with her parents are considered one

reporting unit.

• A husband and wife and their unmarried daughter,

age 18, who is living away from home at college

constitute two reporting units operationally (but only

one family unit analytically).

• Three unrelated persons living in the same dwelling

unit represent three reporting units. 

The first round of the 1996 MEPS averaged 1.09

reporting units per sample dwelling unit. This low

average reflects the fact that a substantial proportion of

sample dwelling units contained only one reporting unit.

In MEPS, analyses are conducted at both the

individual and family levels. Through the reenumeration section of the Round 1 questionnaire, the

status of each individual sampled at the time of the

NHIS interview is classified as “key or non-key” and

“in-scope or out-of-scope.” The “key” and “scope”

indicators, together, define the target sample to be used

for person-level national estimates. They are discussed

in detail next.

In-Scope Persons

Individuals are in scope if they are members of the

civilian noninstitutionalized population. Because a

person’s eligibility for the survey may have changed

since the NHIS interview, sampling re-enumeration

takes place in each subsequent interview for persons in

all households selected into the core survey.

Key Persons

A “key” survey participant is one whose chance of

selection for MEPS is linked to the sample of

households originally selected for NHIS. (College

students interviewed in dorms for NHIS are not

included in MEPS; college students living away from

home are included in MEPS if, during MEPS

enumeration, their parents identified the students’ usual

place of residence as somewhere away from home.) A

person must be key in order to be eligible to receive a

person-level weight. (Other conditions must be met as

well.) 

Key survey participants include all civilian

noninstitutionalized individuals who resided in

households that responded to the nationally

representative NHIS subsample reserved for MEPS.

Members of the Armed Forces who are on full-time

active duty and reside in responding NHIS households

that include other family members who are civilian

noninstitutionalized individuals are also considered key

persons. However, they are considered out of scope for

person-level estimates derived from the survey unless

they re-enter the civilian noninstitutionalized population

for some time during 1996.

Individuals who join the NHIS reporting units that

define the 1996 MEPS HC sample (in Round 1 or later

MEPS rounds) and did not have an opportunity for

selection during the time of the NHIS interview are also

considered key persons. These include newborns,

individuals who were in an institution or outside the

United States, and military personnel previously

residing on military bases who join MEPS reporting

units to live in the community.

College students under age 24 who were

interviewed at dormitories in the 1995 NHIS were

considered ineligible for the 1996 MEPS sample. If an

unmarried college student under age 24 responded to

the 1995 NHIS interview while living away at school

(but not in a dormitory) and, during the MEPS Round 1

interview, was determined to be unmarried, under age

24, and a student with parents living elsewhere who

resided at his/her current housing only during the school

year, he or she was excluded from the sample. If, on the

other hand, the person’s status at the time of the MEPS

Round 1 interview was no longer that of an unmarried

student under age 24 living away from home, then the

person was retained in the 1996 MEPS sample as a key

person.

At the time of the MEPS Round 1 interview with

NHIS sample respondents, a question was asked to

determine if any related college students under age 24
4

usually lived in the sampled household but were

currently living away from home and going to school.

These college students were considered key persons.

They were identified and interviewed at their college

address but were linked to the sampled household for

family analyses. Some of these college students living

away from home at the time of the Round 1 interview

had been identified as living in a sampled household at

the time of the 1995 NHIS interview. The remainder

were identified at the time of the MEPS Round 1

interview.

When key in-scope MEPS participants move out (in

Round 1 or later rounds) and join or create another

family, data on all members who are related by blood,

marriage, adoption, or foster care to the key in-scope

MEPS participants are obtained from the time that the

key in-scope person(s) joined the family. Similarly, data

are collected (in Round 1 and later rounds) on all related

persons who join families already participating in

MEPS, whether the new persons are key or non-key.

If key in-scope MEPS participants enter a nursing

home, thus leaving the civilian noninstitutionalized

population, data are collected during their stay in the

nursing home. Data are not collected for other key inscope persons after they leave the civilian

noninstitutionalized population of the United States. If

they return to the U.S. civilian noninstitutionalized

population, these persons are once again eligible for data

collection in MEPS.

Non-Key Persons

Persons who were not living in the original sampled

dwelling unit at the time of the 1995 NHIS interview but

were part of the civilian noninstitutionalized population

at that time are considered non-key. If such persons

happen to be living in a MEPS sampled household in

Round 1 or later rounds, MEPS data (e.g., utilization

and income) will be collected for the period of time they

are part of the sampled unit to permit family analyses.

Non-key persons who leave a sample family without an

accompanying key in-scope person will not be

recontacted for subsequent interviews. Non-key

individuals are not part of the target sample used to

obtain person-level national estimates.

Eligible Persons

People are eligible for data collection in MEPS if

they are key and in scope. Individuals who are non-key

and in scope, as well as members of a family with at

least one member who is key and in scope, are also

eligible for data collection. Out-of-scope individuals

who are full-time active-duty members of the Armed

Forces are also eligible for MEPS data collection for the

time period during which they are members of a family

with at least one member who is key and in scope. 

Round 1 Field Results

The 1995 NHIS subsample eligible for the 1996

MEPS consisted of 10,639 responding NHIS dwelling

units. Of these, 10,597 (99.6 percent) had sufficient

information to permit MEPS data collection. Table 1

summarizes response rates for MEPS (conditional on

response to NHIS) at both the dwelling-unit and

reporting-unit levels. The 10,509 sample dwelling units

that had sufficient address information from NHIS and

were considered eligible for MEPS contained a total of

11,424 reporting units. Of these reporting units, 83.1

percent responded to the first MEPS interview, 2.2

percent could not be located, and 14.7 percent were

located but did not participate in the MEPS interview. 

For a reporting unit to be eligible for MEPS data

collection, it had to include at least one key individual

who was a member of the civilian noninstitutionalized

population between January 1, 1996, and the date of the

MEPS interview. Within the 10,597 sampled dwelling

units that constitute the MEPS Round 1 sample, 11,590

reporting units were identified and targeted for data

collection. Of these, 166 reporting units were

determined to be ineligible for the 1996 MEPS. MEPS

sample ineligibility for Round 1 was a consequence of

the following situations:

• All members of the reporting unit died prior to

January 1, 1996 (21 cases). 

• All members of the reporting unit were full-time

active-duty members of the military prior to January

1, 1996 (4 cases). 

• All members of the reporting unit were

institutionalized prior to January 1, 1996 (26 cases).
5

• All members of the reporting unit left the United

States prior to January 1, 1996 (29 cases).

• All members of the reporting unit were ineligible for

data collection for two or more of the above reasons

(e.g., one member died prior to January 1, 1996, and

the other was institutionalized prior to January 1,

1996) (86 cases). 

Of the 11,424 eligible reporting units targeted for

interviews in Round 1, 9,488 (83.1 percent) responded to

the first MEPS interview (Table 1). The remaining 1,936

eligible reporting units (16.9 percent) were classified as

nonrespondents because of:

• Refusal to complete the interview (1,506 cases).

• Unavailable during the field period (43 cases).

• Unable to locate (251 cases).

• Illness (27 cases). 

• Other nonresponse (109 cases).

Since the MEPS sample is a nationally

representative subsample of households that were part of

the 1995 NHIS, the response rate that has implications

for the development of national estimates from MEPS is

a function of the response rates to both surveys.

Specifically, the overall Round 1 MEPS response rate is

the product of the following three components: 

• The NHIS response rate achieved for households

eligible for MEPS (93.9 percent).

• The proportion of NHIS units selected that had

sufficient information to permit inclusion in MEPS

(99.6 percent).

Table 1. Response rates for the 1996 MEPS Household Component, Round 1 

Dwelling units Reporting units

Item Number Percent Number Percent

Sample cases 10,597 — 11,590 —

Sample eligibles1 10,509 100.0 11,424 100.0

Respondents2 8,793 83.7 9,488 83.1

Nonrespondents 1,716 16.3 1,936 16.9

Unable to locate — — 251 2.2

Nonparticipants — — 1,685 14.7

188 sample dwelling units and 166 reporting units were deemed ineligible for MEPS. To be eligible for MEPS, a unit must

contain at least 1 individual from an NHIS sample household who was also a member of the civilian noninstitutionalized

population between January 1, 1996, and the date of the MEPS interview. Most of the ineligible dwelling units consisted of

individuals who died or were institutionalized prior to January 1, 1996.

2A dwelling unit is classified as a respondent if at least 1 member of the reporting unit responded to the survey. A reporting

unit is classified as a responding unit if all members responded.

Note: MEPS is the Medical Expenditure Panel Survey. NHIS is the National Health Interview Survey. MEPS response rates

are conditional on NHIS response.

Source: Center for Cost and Financing Studies, Agency for Health Care Policy and Research: Medical Expenditure Panel

Survey Household Component, 1996 (Round 1).
6

• The conditional response rate for MEPS Round 1

reporting units (83.1 percent). 

The combination of these factors resulted in a

response rate of 77.7 percent (.939 × .996 × .831) for the

1996 MEPS Round 1 HC (Cohen and Machlin, 1998). 

In Table 1, the conditional response rates for the

1996 MEPS Round 1 survey are shown at both the

dwelling-unit level and the reporting-unit level. Since

there is generally a one-to-one correspondence between

a dwelling unit and a reporting unit, the conditional

response rates for both are similar (83.7 and 83.1

percent, respectively). While the reporting-unit

response rate is more meaningful from an operational

perspective, the dwelling-unit response rate is also

provided because the MEPS estimation weights are

initially adjusted for nonresponse at this level.

Sampling Weight Specifications

Because of the complex design of the MEPS HC,

the MEPS sample data must be appropriately weighted

to obtain approximately unbiased national estimates for

the U.S. civilian noninstitutionalized population. The

sampling weights developed for this purpose reflect the

disproportionate sampling adopted in NHIS to

oversample minority populations. They also reflect

adjustments for:

• Complete nonresponse of eligible sample units.

• Partial response of survey participants providing data

for only a portion of the time in 1996 during which

they were eligible to respond.

• Poststratification to more accurate population totals

obtained from the Current Population Survey (CPS).

The 1996 MEPS estimation weights are built from

the estimation weights developed for the 1995 NHIS. To

reduce the impact of large sampling weights on resultant

variances of survey estimates, the MEPS estimation

weights reflect a weight-trimming adjustment. The 1996

MEPS dwelling-unit weights also include an initial ratio

adjustment to population estimates for selected

socioeconomic measures derived from the full 1995

NHIS and subsequent adjustments for nonresponse to

the first round of MEPS. In addition, the MEPS

estimation weights developed at the person and family

levels reflect additional adjustments that poststratify the

MEPS estimates to more accurate population totals

obtained from CPS. The details of the development of

MEPS estimation weights are described in this section. 

Base Weights

Because the 1995 NHIS and MEPS are linked, the

sampling weights developed for NHIS serve as the base

weights for the 1996 MEPS. More specifically, the base

weight for a dwelling unit selected in the 1996 MEPS is

the nonresponse-adjusted 1995 NHIS quarter-specific

estimation weight of the reference person in the primary

reporting unit of a sampled dwelling unit. The reference

person is the person who owns or rents the house. This

NHIS estimation weight reflects the household’s

probability of selection in NHIS and adjustments for

NHIS survey nonresponse. 

More specifically, if 

P(i) is the ith dwelling unit’s probability of 

selection in NHIS to represent the Qth 

quarter of 1995 and includes 

disproportionate values associated with 

the oversampling of minorities, and 

A(c) adjusts for NHIS nonresponse within 

nonresponse-adjustment class c, of 

which dwelling unit i is a member,

then the NHIS estimation weight NHISWTQ(i), for the

ith dwelling unit selected for MEPS in quarter Q = 2 or

3, would take the form

NHISWTQ(i) = (1/P(i)) × A(c)

The NHIS quarter-specific base weight was obtained

by using the final-quarter basic NHIS weight from the

1995 NHIS analytical file delivered to AHCPR. The

available estimation weight (HIS.WT.BF) also included a

first-stage ratio adjustment (HIS.ADJ) that adjusts the

initial NHIS population estimates to Census Bureau

estimates for cross-classification of the population based

on race/ethnicity (Hispanic, non-Hispanic black, other),

Census region (East, Midwest, South, and West), and

MSA classification (MSA/non-MSA). This component

needed to be factored out of the NHIS estimation weight,

since the first-stage ratio adjustment was implemented in
7

NHIS without reflecting the subsampling of NHIS PSUs

for MEPS that occurred by MSA classification.

Consequently, the initial MEPS base weight (WT.MEP.I)

was specified as 

WT.MEP.I = HIS.WT.BF/HIS.ADJ 

Use of the NHIS quarter-specific estimation weight

across multiple quarters of 1995 to produce a national

estimate required that the weight be divided by the

number of quarters being pooled. Since the MEPS

sample was confined to quarters 2 and 3 of calendar year

1995, the NHIS quarter weight, HIS.WT.BF, was initially

divided by 2, HIS.WT.BF/2 . Since the MEPS sample

was restricted to panels 1 and 3 out of a four-panel NHIS

design, it represented a 50-percent subsample of NHIS.

Consequently, the NHIS quarter weight, HIS.WT.BF/2

(representing quarters 2 and 3), was further multiplied by

2 to reflect the 50-percent subsample considered for

MEPS. Consequently, specification of the initial MEPS

base weight as 

WT.MEP.I = HIS.WT.BF/HIS.ADJ 

reflects the restriction of the NHIS sample to quarters 2

and 3 and a 50-percent sample for the 1996 MEPS. 

As mentioned previously, unmarried students ages

17-23 who were living in dormitories and had been

respondents in the 1995 NHIS were not eligible for the

1996 MEPS. Furthermore, a very small set of NHIS

dwelling units (54) that were determined to be eligible

for MEPS at the time of sample selection could not be

linked back to the 1995 NHIS analytical file that was

provided a year later. The following strategy was

implemented to obtain a base weight for these dwelling

units. Median values of WT.MEP.I were determined for

the dwelling units eligible for MEPS that linked back to

the NHIS analytical file, based on classes defined by a

cross-classification of the minority status of the dwelling

unit (1 if the dwelling unit has a Hispanic or black

member, 2 otherwise) and 20 mutually exclusive and

exhaustive distinct sampling strata defined for NHIS at

the segment level for oversampling purposes. MEPS

base-weight assignments for the nonlinked cases were

made based on the median value of WT.MEP.I for the

class with which they were associated. 

Trimming Base Weights

An initial examination of the distribution of the

MEPS base weights identified a high level of variability.

To correct for the impact of large sampling weights on

resultant MEPS variance estimates, the initial MEPS

base weights were trimmed according to the following

specifications. 

In each of the 40 classes (c) determined by a crossclassification of the dwelling unit’s minority status and

the 20 NHIS sampling strata defined at the segment level

for oversampling purposes, the mean of the initial

MEPS base weight, MEANDUWT(c) =

MEAN(WT.MEP.I(iεc)) was computed. If the initial

MEPS base weight for the dwelling units within a given

class c was greater than 3 times the mean of the base

weights, the weight was truncated to that value.

Otherwise, the sampling weight retained its initial value.

More specifically, for class c, where c = 1,...40, 

If WT.MEP.I(i) > 3 × MEANDUWT(c),

then TRIMFAC = 3 × (MEANDUWT(c)/ WT.MEP.I(i)); 

If WT.MEP.I(i) ≤ 3 × MEANDUWT(c),

then TRIMFAC = 1.

Consequently, the trimmed MEPS weights were

specified as 

TRIMDUWT(i) = TRIMFAC × WT.MEP.I(i)

While only a few sampling weights were modified, the

largest MEPS base weight was reduced by nearly 50

percent.

Ratio Adjustment of Trimmed Base

Weights 

To improve the accuracy of the MEPS estimates, the

trimmed dwelling unit weights were subsequently ratio

adjusted to population estimates derived from the full

1995 NHIS, using data from the first three quarters of

the 1995 NHIS (all of the 1995 NHIS that was available

at the time of MEPS sampling weights development).

The following measures were used in specifying the
ratio-adjustment cells to facilitate the adjustment at the

dwelling unit (DU) level:

• MSA status (central city, MSA; not central city,

MSA; non-MSA).

• Family income classification of reference person

(below poverty; under $35,000 but above poverty;

equal to or greater than $35,000; unknown). 

• Employment status of reference person (employed;

not employed).

• Race/ethnicity of reference person (Hispanic; black

non-Hispanic; other).

• Dwelling-unit level measure of activity limitations

(at least one person in DU either cannot perform

major activity or is limited in kind or amount of

major or other activities; no member of DU has an

activity limitation).

These measures were selected to represent a set of

measures that related to the oversampling done in NHIS

(DU minority status and MSA status). They also

represented socioeconomic and health-specific

measures potentially associated with health care use,

expenditures, and insurance coverage that are not used

to define the family- and person-level poststratification

adjustments in MEPS. For dwelling units associated

with more than one reporting unit, the reference person

and family income of the primary reporting unit were

used for classification purposes. Cross-classification of

these measures yielded 144 weighting class cells to

implement the ratio adjustment to more accurate

national estimates at the household level based on the

entire 1995 NHIS sample for quarters 1-3.

More specifically, the DU-level ratio adjustment for

the cth weighting class takes the form

where iεc represents all NHIS dwelling units in c

selected for the 1996 MEPS, TRIMDUWT(i) represents

the trimmed initial NHIS base weight for the ith

dwelling unit selected for MEPS, and NHISDU(c)

represents the national population estimate at the

dwelling-unit level for weighting class c, derived from

the 1995 NHIS using data from quarters 1-3.

Consequently, the ratio-adjusted MEPS dwelling unit

weight DUPSWT(i) for the ith dwelling unit associated

with class c, adjusted to population estimates derived

from the full 1995 NHIS, takes the form

DUPSWT(i) = A(c) × TRIMDUWT(i)

The sum of the ratio-adjusted and trimmed MEPS

dwelling unit weights for the 10,597 NHIS dwelling

units fielded for the 1996 MEPS was 104,002,800.

Round 1

Nonresponse-Adjusted Dwelling Unit Weights

Of the 10,509 dwelling units eligible for data

collection in the first round of the 1996 MEPS, 8,793

(83.7 percent) contained at least one reporting unit that

responded to the MEPS interview. Since survey

nonresponse is potentially a significant source of bias

in survey estimates, the MEPS dwelling unit sampling

weights included an adjustment to help reduce its

potential for bias. In general, the greater the difference

among subgroups in response rates and the analytic

characteristic(s) of interest, the greater is the need to

adjust survey weights for nonresponse. In MEPS, a

weighting class nonresponse adjustment was

implemented, under the assumption that nonresponding

sampling units would have responded in a manner

similar to that of respondents with similar

sociodemographic and economic characteristics within

the same adjustment class. Properly designed, a

weighting class nonresponse adjustment strategy can

result in reduced nonresponse bias. The technique

requires that the sample be partitioned into mutually

exclusive classes, with classification information

available for both responding and nonresponding units

(Cox and Cohen, 1985). 

Analyses were conducted of characteristics

associated with differential nonresponse in MEPS.

These analyses identified the most important measures

to use in developing a nonresponse adjustment to the

MEPS sampling weights to correct for potential

nonresponse bias at the dwelling-unit level (Cohen and

Machlin, 1998; DiGaetano and Goksel, 1996). To

facilitate these comparisons, the demographic,

8

Σ TRIMDUWT(i)

NHISDU(c) A(c) =

iεc
9

socioeconomic, health-related, and interview-specific

profiles of respondents and nonrespondents were

examined, based on available data for both groups from

the 1995 NHIS.

Based on the results of these analyses, weighting

classes were specified for the MEPS Round 1 dwelling

unit nonresponse adjustments. They were defined by

cross-classifications of the following measures:

• Family income of primary reporting unit (less than

$10,000; $10,000-$19,999; $20,000-$34,999;

$35,000 or more; unknown).

• Size of dwelling unit (one; two; three; four; five or

more).

• MSA size (MSA, population 500,000 or more;

MSA, population less than 500,000; non- MSA).

• Region (Northeast; Midwest; South; West).

• Employment classification of reference person

(government; private sector; not in labor force/never

worked/worked without pay; unknown or under 18

years of age).

• DU-level personal help measure (units with at least

one member unable to perform personal care

activities or other routine needs; remaining units

with person 70 and over; remaining units with no

limitations).

• Propensity to cooperate, based on providing phone

number during NHIS (phone number provided;

phone present but no number provided; no phone;

unknown).

• Age of reference person (under 25; 25-34; 35-44;

45-64; 65 and over).

• Race/ethnicity of reference person (Hispanic; black

non-Hispanic; other).

• Sex of reference person.

• Marital status (married, spouse present; other).

Overall, 49 cells were identified based on crossclassifications of these measures, with cell collapsing

specified according to a hierarchy determined by

significance level.

More specifically, the nonresponse adjustment for

the cth weighting class takes the form

where

DUPSWT(i) is the initial MEPS Round 1 dwelling unit

weight for the ith sample dwelling unit, which reflects

the reciprocal of the dwelling unit’s selection probability

for MEPS and a poststratification adjustment to 1995

NHIS population totals;

E(i) = 1 for all MEPS dwelling units selected for the 

Round 1 interview; E(i) = 0 otherwise;

R(i) = 1 for all selected MEPS dwelling units 

responding in Round 1, R(i) = 0 otherwise; and 

iεc represents eligible dwelling units classified in 

weighting class c. 

Consequently, the estimation weight adjusted for MEPS

Round 1 dwelling unit nonresponse, WGTDU1(i), for

the ith dwelling unit associated with class c, takes the

form

WGTDU1(i) = B(c) × DUPSWT(i)

The sum of the nonresponse-adjusted MEPS dwelling

unit weights for the 8,793 eligible dwelling units with at

least one responding reporting unit in Round 1 of

MEPS was 102,892,600.

Family-Level Estimation Weights

In MEPS, a family is defined as a person or group

of persons who are living together and are related by

blood, marriage (or partnerships that are viewed as

such), adoption, or other family associations. Any

related college students under age 24 who usually live in

the sampled household but are currently living away

from home and going to school full time are considered

to be members of the family. These college students are

considered key persons in MEPS and are interviewed at

their college address but linked to the sampled

household for family analyses. Families in MEPS

without college students living away from home were

identified as single reporting units. Families in MEPS

with college students living away from home were

identified by linking the student reporting unit(s) back

to their parent(s)’ reporting unit. Σ R(i)DUPSWT(i)

B(c) =

iεc

Σ E(i)DUPSWT(i)

iεc
To be considered a responding family in MEPS for

the Round 1 interview, the family needed to include at

least one person who was key, in scope, and eligible for

data collection. Furthermore, all such key, in-scope, and

eligible persons had to have responded for their entire

period of eligibility in 1996 covered by the Round 1

interview. Each family in MEPS characterized as

responding was assigned the weight of its corresponding

dwelling unit (adjusted for nonresponse): 

WGTFAM(i) = WGTDU1(i)

Overall, 9,488 reporting units responded in the first

round of MEPS. After linking the responding student

reporting units back to their parent(s)’ family, this

translated to 9,388 responding families. 

The initial weights at the family level were then

further poststratified to reflect population estimates

obtained from the March 1996 CPS for unrelated

individuals plus families. This poststratification also

served as an adjustment for nonresponse at the family

level. The weighting classes that were considered for the

family-level poststratification adjustment were defined

by a cross-classification of the following variables,

defined at the time of the MEPS Round 1 interview:

• Family type—reference person (oldest person when

there is no reference person) married and spouse

present; male reference person and spouse not

present; female reference person and spouse not

present.

• Race/ethnicity of reference person (oldest person

when there is no reference person)–Hispanic; black

non-Hispanic; other.

• Region—Northeast; Midwest; South; West.

• MSA status—MSA; non-MSA. 

• Number of persons in family–one; two; three; four;

five or more.

• Age of reference person (oldest person when there

is no reference person)–under 35; 35-44; 45-64; 65

and over.

More specifically, the family-level poststratification

adjustment for the cth weighting class takes the form

where CPSFAM(c) represents the national population

estimate at the family level for weighting class c,

derived from the March 1996 CPS; iεc represents all

MEPS family units classified in c that responded to the

Round 1 interview; and WGTFAM(i) represents the

initial MEPS family-level weight for the ith family unit

responding in the 1996 MEPS. Consequently, the Round

1 poststratified MEPS family unit weight WGTRU1(i),

for the ith family unit associated with class c, adjusted

to population estimates derived from the March 1996

CPS, takes the form of:

WGTRU1(i) = C(c) × WGTFAM(i)

The weighted estimate of the number of family

units (including single-person units) containing at least

one member of the U.S. civilian noninstitutionalized

population is 110,206,950. It is obtained by summing

the poststratified MEPS family unit weights for the

9,388 MEPS family units that responded to the Round 1

interview. In the development of family-level attributes

in MEPS, all eligible and responding persons who are in

scope, both key and non-key individuals, should be

included. 

Person-Level Estimation Weights

Estimation weights were assigned for key in-scope

MEPS participants who were in responding Round 1

reporting units and for whom data were obtained for

their entire Round 1 period of eligibility in 1996. To be

considered a responding survey participant in MEPS for

the Round 1 interview, the person needed to be in scope,

with data provided for their entire Round 1 period of

eligibility in 1996. All key, in-scope, and eligible sample

participants in MEPS who satisfied these criteria for

survey response were assigned estimation weights. The

initial person-level estimation weight assigned to these

MEPS survey respondents was the corresponding

poststratified estimation weight for the family unit of

which they were a member,

WGTPER(i) = WGTRU1(i)

Overall, 23,612 key, in-scope, and eligible

individuals were classified as survey respondents in the

first round of MEPS. The Round 1 MEPS person-level

10

Σ WGTFAM(i)

C(c) =

iεc

CPSFAM(c)
11

weights were then poststratified to population totals

obtained from the March 1996 CPS. 

To establish consistency between family-level and

person-level estimates, the final person weight for the

reference person for each family (oldest person when

there is no reference person), in addition to married

couples living together, was the value of the MEPS

family-unit weight: 

WGTSP1(i) = WGTRU1(i)

The person-level estimation weights of all other MEPS

key, in-scope, and eligible survey respondents (e.g.,

children of reference persons) were poststratified to

population totals obtained from the March 1996 CPS.

Weighting classes were defined by a cross-classification

of the following variables:

• Region (Northeast, Midwest, South, West).

• Race/ethnicity (Hispanic, black non-Hispanic, other).

• Sex (male, female).

• Age at interview date (under 1, 1-4, 5-9, 10-14, 15-

19, 20-29, 30-34, 35-44, 45-54, 55-59, 60-64, 65-69,

70-74, 75-79, 80 and over). 

This adjustment served as both a nonresponse and

poststratification adjustment at the person level. The

person-level poststratification adjustment factor for the

cth weighting class takes the form

D(c) = 1

for the reference person for each family (oldest person

when there is no reference person), in addition to

married couples living together (denoted by L(i) = 1;

L(i) = 0 otherwise). For others, it takes the form

where CPSPER(c) represents the national population

estimate at the person level for weighting class c,

derived from the March 1996 CPS; iεc represents all

MEPS key and in-scope survey participants classified in

c who responded to the Round 1 interview; and

WGTPER(i) represents the initial MEPS person-level

weight for the ith person responding in the 1996 MEPS.

Consequently, the Round 1 poststratified MEPS person

weight WGTSP1(i), for the ith person associated with

class c, adjusted to population estimates derived from

the March 1996 CPS, takes the form

WGTSP1(i) = D(c) × WGTPER(i).

The weighted estimate of the number of persons

who were members of the U.S. civilian

noninstitutionalized population as of spring 1996 is

263,515,813. It can be derived by summing the

poststratified MEPS person weights for the 23,612

MEPS key and in-scope survey participants classified as

respondents for the Round 1 interview, as indicated on

MEPS HC Public Use File HC-001: 1996 Panel Round

1 Population Characteristics (AHCPR Pub. No. 97-

DP20, available on CD-ROM or through the MEPS

Web site at <http://www.meps.ahcpr.gov/>). 

Full-Year 1996

Part-Year Nonresponse Adjustment

The MEPS Round 1 person-level weight was

developed to make estimates of the health care

experience and insurance coverage of the U.S. civilian

noninstitutionalized population for the first half of 1996.

An annual person-level weight for 1996 was developed

for deriving person-level estimates that cover all of

calendar year 1996. Application of this weight permits

the derivation of national estimates of the health care

use, expenditures, insurance coverage, and sources of

payment for the civilian noninstitutionalized population

for calendar year 1996. 

In order to be considered a responding survey

participant in MEPS for the purpose of deriving annual

1996 estimates, the person had to be key and in scope,

with data provided for their entire period of eligibility in

1996. If all the key, in-scope, and eligible sample

participants in MEPS with positive values for the MEPS

Round 1 person-level weight—in addition to new key

and in-scope respondents who joined a responding

household in 1996 after Round 1—had responded for

their entire period of eligibility in 1996, no additional

Σ WGTPER(i)(1 − L(i))

D(c) =

iεc

iεc CPSPER(c) −Σ WGTPER(i)L(i)
adjustment for part-year survey nonresponse over the

course of Rounds 1 through 3 would have been

necessary. (New respondents acquired the sampling

weight of the family they joined.) However, of 23,881

sample participants identified in MEPS, 21,571 (90.33

percent) provided data for their entire period of

eligibility in 1996. Consequently, after factoring in the

impact of survey attrition, the overall MEPS personlevel response rate for deriving annual estimates was

70.2 percent (.777 × .903). 

Since survey nonresponse is potentially a

significant source of error or bias in survey estimates,

the MEPS full-year sampling weights included an

adjustment for survey attrition to help reduce its

potential impact. The characteristics that distinguish

MEPS respondents with survey response for their entire

period of eligibility in 1996 from Round 1 participants

who discontinued survey participation were analyzed.

This analysis identified the most important variables to

incorporate into the nonresponse adjustments to the

MEPS sampling weights to correct for part-year survey

nonresponse. It was based only on data from the first

two rounds of the survey because relevant Round 3 data

for 1996 were unavailable at the time of the analysis. A

logistic regression analysis identified the most important

measures to include in specifying a nonresponse

adjustment to the MEPS sampling weights to correct for

part-year response for calendar 1996 at the person level.

Based on the results, weighting classes were specified

for the MEPS full-year person-level nonresponse

adjustments. They were defined by cross-classifications

of the following measures as of Round 1 (or as of the

first eligible round in MEPS for key and in-scope

respondents who joined a household after Round 1):

• Round 1 interview classification (no initial refusal,

initial refusal).

• Size of MEPS family (one, two, three, four, five or

more).

• MSA (MSA, non-MSA).

• Age (under 20, 20-29, 30-44, 45-64, 65 and over).

• Marital status of reference person (married,

widowed, divorced, separated, never married).

Overall, 218 cells were identified based on crossclassifications of these measures. Cell collapsing was

specified according to a hierarchy determined by

significance level.

The nonresponse adjustment for the cth weighting

class takes the form

where

WGTSP1(i) is the MEPS Round 1 poststratified

person-level weight for the ith Round 1 respondent,

and WGTSP1(i) = WGTRU1(i) for key and in-scope

respondents who joined a household in 1996 after

Round 1 (here, the new respondent acquires the

sampling weight of the family joined);

E(i) = 1 for all MEPS Round 1 respondents with

positive values of WGTSP1(i) and for key and inscope respondents who joined a responding

household in 1996 after Round 1 with positive

values of WGTSP1(i); E(i) = 0 otherwise;

R(i) = 1 for all persons with E(i) = 1 who responded

for their entire period of eligibility in 1996; R(i) = 0

otherwise; and 

iεc represents all key and in-scope MEPS full- and

part-year respondents classified in weighting class c.

Consequently, the estimation weight adjusted for survey

attrition in MEPS covering calendar year 1996,

WGTSP2(i), for the ith person associated with class c,

takes the form

WGTSP2(i) = F(c) × WGTSP1(i)

for the 21,571 key and in-scope survey participants who

responded for their entire period of eligibility in 1996.

Person-Level Estimation Weights

The subset of the 21,571 key and in-scope survey

participants who responded for their entire period of

eligibility in 1996 and who were also in scope on

December 31, 1996, had their part-year nonresponse12

Σ R(i)WGTSP1(i)

F(c) =

iεc

iεc

Σ E(i)WGTSP1(i)
13

adjusted annual estimation weights further poststratified

to Census Bureau population estimates as of December

1996. The person-level estimation weights, WGTSP2(i),

of the 21,326 sample participants that meet these criteria

were poststratified to population totals obtained from

the March 1997 CPS and further scaled to reflect

Census Bureau population estimates as of December

1996 within weighting classes defined by a crossclassification of the following variables: 

• Sex (male, female).

• Age as of December 31, 1996 (under 1, 1-4, 5-9, 10-

14, 15-19, 20-24, 25-29, 30-34, 35-44, 45-54, 55-59,

60-64, 65-69, 70-74, 75-79, 80 and over). 

• Race/ethnicity (Hispanic, black non-Hispanic, other).

• Region (Northeast, Midwest, South, West).

• MSA (MSA, non-MSA).

Within each of the weighting classes (cεC)

associated with a given age-by-sex cross-classification

(C), the population totals derived from the March 1997

CPS were further adjusted by the factor SCALE(C),

which was defined as the ratio of the December 1996

Census Bureau population estimate to the March 1997

population estimate derived from the CPS (Table 2). 

More specifically, the person-level poststratification

adjustment for the cth weighting class takes the form

where

MAR97CPS(C) represents the national population

estimate at the person level for weighting class c,

derived from the March 1997 CPS;

SCALE(C) represents the ratio of the December

1996 Census Bureau population estimate to the

March 1997 population estimate derived from the

CPS for the specific cross-classification of age and

sex associated with cell C;

iεc represents all key and in-scope survey

participants associated with cell c (cεC) who

responded for their entire period of eligibility in

1996 and were also in scope on December 31, 1996;

and

WGTSP2(i) represents the annual person-level

estimation weight for calendar year 1996 adjusted

for survey attrition.

Consequently, the MEPS full-year 1996 person-level

weight WGTSP96(i) for the ith key, full-year survey

participant in scope as of December 31, 1996, who is

associated with class c, adjusted to population estimates

derived from the March 1997 CPS and further scaled to

Census Bureau estimates for December 1996, takes the

form

WGTSP96(i) = G(c) × WGTSP2(i)

The remaining 245 key in-scope MEPS survey

participants responded for their entire period of

eligibility in 1996 but were not in scope as of December

31, 1996 (e.g., persons who died during the survey

year). These participants maintained their estimation

weight, adjusted for survey attrition. Consequently, their

MEPS full-year person-level weight was specified as 

WGTSP96(i) = WGTSP2(i)

The weighted estimate of the number of persons in

the U.S. civilian noninstitutionalized population as of

December 1996 is 265,439,511. It can be derived by

summing the poststratified MEPS person weights for

the 21,326 MEPS key and in-scope survey participants

classified as respondents and in scope as of December

31, 1996, as indicated on the MEPS HC Public Use File

HC-003: 1996 Panel Population Characteristics and

Utilization Data for 1996 (AHCPR Pub. No. 98-DP12,

available on CD-ROM or through the MEPS Web site at

<http://www.meps.ahcpr.gov/>). Once the full-year

insurance coverage measures are available for release,

analysts can produce cross-sectional national insurance

coverage estimates as of December 1996 with the

MEPS data. However, they should restrict their sample

to this set of survey participants who were in scope as

of December 31, 1996. Similarly, the weighted estimate

of the number of persons in the U.S. civilian

noninstitutionalized population over the course of 1996

is 268,130,477. It can be derived by summing the final

poststratified MEPS person weights for the 21,571

MEPS key and in-scope survey participants who

responded for their entire period of eligibility in 1996.

iεc

Σ WGTSP2(i)

G(c) =

MAR97CPS(c) × SCALE(C)
14

Table 2. Population estimates by sex and age for December 1996 and March

1997: United States

December 19961 March 19972

Age in years Male Female Male Female

Total 129,578,301 135,861,210 129,842,460 136,084,232

Under 1 1,989,676 1,902,075 1,959,414 1,856,886

1-4 8,162,745 7,787,372 8,118,381 7,846,632

5-9 10,322,287 9,848,773 10,428,712 9,842,699

10-14 9,990,073 9,526,892 9,970,793 9,534,281

15-19 9,723,221 9,327,806 9,766,326 9,377,121

20-24 8,728,774 8,730,416 8,635,045 8,719,707

25-29 9,354,544 9,674,812 9,450,287 9,636,289

30-34 10,339,061 10,652,556 10,242,979 10,548,081

35-44 21,458,434 22,046,082 21,546,881 22,147,277

45-54 16,001,003 16,759,899 16,063,659 16,891,429

55-59 5,446,069 5,892,934 5,569,213 6,003,373

60-64 4,644,237 5,191,637 4,686,964 5,206,925

65-69 4,415,868 5,236,207 4,321,136 5,179,642

70-74 3,721,987 4,787,277 3,764,159 4,750,254

75 and over 5,280,322 8,496,472 5,318,511 8,543,637

1Obtained from the U.S. Bureau of the Census.

2Computed from the Current Population Survey March 1997 data file.

Note: Civilian noninstitutionalized population.
15

Analysts who want to produce annual 1996 health care

utilization and expenditure estimates should include all

of these 21,571 key and in-scope MEPS survey

participants for the purposes of estimation. A future

MEPS data release will include an updated person-level

weight further poststratified by poverty status

classification and estimation weights to support annual

1996 family-level health care use and expenditure

estimation.

Variance Estimation

The sample design of the MEPS HC includes

stratification, clustering, multiple stages of selection,

and disproportionate sampling. This complex sample

design results in serious departures from the

assumptions of simple random sampling. Furthermore,

the MEPS sampling weights reflect differential

adjustments for survey nonresponse and

poststratification. These survey design and estimation

complexities require special consideration with regard

to variance estimation and analysis. To obtain accurate

estimates of the standard errors associated with MEPS

person- and family-level survey estimates, for either

descriptive statistics or more sophisticated analyses

based on multivariate models, the MEPS survey design

complexities need to be taken into account. Several

methods for estimating sampling variances that adjust

for survey design complexities have been developed

that are appropriate for analytical applications tied to

MEPS (Cohen SB, 1997b). These variance estimation

strategies include the Taylor-series linearization method,

balanced repeated replication, and the jack-knife

method.

The MEPS public use files include variables

necessary for implementing a Taylor-series variance

estimation approach for survey estimates. When using

such an approach, the sampling strata and associated

PSUs that define the MEPS survey design need to be

specified. The corresponding variables on the MEPS

Round 1 database (AHCPR Pub. No. 97-DP20) are

VARSTRT1 and VARPSU1, respectively. Similarly, the

corresponding variables on the MEPS full-year 1996

utilization estimates database (AHCPR Pub. No. 98-

DP12) are VARSTR96 and VARPSU96. Specifying a

“with replacement” design in a variance estimation

software package appropriate for the analysis of

complex survey data that utilizes the Taylor-series

approach, such as SUDAAN (Shah, Barnwell, Bieler, et

al., 1996) or Stata (StataCorp, 1997) will yield standard

errors that have been appropriately adjusted for survey

design complexities.

The number of degrees of freedom associated with

estimates of variability indicated by such statistical

software packages may not appropriately reflect the

actual number. For purposes of variance estimation, it is

estimated that MEPS sample estimates for the general

population derived at the national level have

approximately 100 degrees of freedom. 

Summary

Because of the national scope and depth of the

MEPS data collection effort and because MEPS survey

estimates are used to inform national health policies, it

is particularly important to use estimation strategies that

improve the quality and accuracy of survey estimates.

Research was conducted to help ascertain potential

sources of bias that were attributable to MEPS dwelling

unit nonresponse; these findings were incorporated in

the specification of the MEPS weights adjustment

strategy to help reduce the impact of nonresponse bias.

The MEPS sample is linked to NHIS, so detailed

information on the sociodemographic and health

characteristics of the eligible MEPS sample was

available to inform the investigation. This investigation

revealed that the dwelling units responding to the first

round of the MEPS HC differed from the

nonrespondents in a number of dimensions. The

multivariate analysis showed that family income,

dwelling unit size, health status of household members

(as measured by personal help needs), phone

availability, MSA size, and item nonresponse for

employment classification were significant factors in

distinguishing MEPS respondents. The measures most

significant in differentiating MEPS survey response

status were used in the specification of the MEPS

Round 1 dwelling unit nonresponse adjustments.

Identification of weighting classes in MEPS that

capture the greatest variation in response rates across

subgroups should reduce the bias attributable to survey

nonresponse.

An analysis was done of the characteristics that

distinguish MEPS respondents with survey response for
16

their entire period of eligibility in 1996 from the Round

1 participants who discontinued survey participation.

This analysis identified the most important measures to

include in specifying a nonresponse adjustment to the

MEPS estimation weights to correct for part-year survey

nonresponse. A logistic regression analysis identified

characteristics that distinguished the MEPS full-year

respondents from their part-year respondent

counterparts. These are the most important measures to

include in specifying a nonresponse adjustment to the

MEPS sampling weights to correct for part-year

response for calendar year 1996 at the person level.

Family size, residence by MSA classification, age,

marital status, and reluctance to participate were found

to be important factors in distinguishing the MEPS partyear respondents from their full-year counterparts. 

The overall MEPS person-level response rate for

deriving annual 1996 estimates was 70.2 percent, after

adjusting for the multiplicative effects of nonresponse to

NHIS, nonresponse to the first round of MEPS, and

survey attrition. To further improve the accuracy of

MEPS survey estimates, additional poststratification

adjustments were incorporated in the development of

the annual MEPS estimation weights. The

poststratification adjustments relied on population

estimates derived from the CPS and other Census

Bureau sources. A detailed summary of the MEPS

estimation weight specifications has been provided in

this report to ensure a better understanding of the

estimation procedures that were adopted.

References

Arnett RA, Hunter E, Cohen S, et al. The

Department of Health and Human Services’ Survey

Integration Plan. In: Proceedings of the American

Statistical Association (ASA). Section on Government

Statistics; 1996 Aug; Chicago. Alexandria (VA):

American Statistical Association; 1996.

Cohen JW. Design and methods of the Medical

Expenditure Panel Survey Household Component.

Rockville (MD): Agency for Health Care Policy and

Research; 1997. MEPS Methodology Report No. 1.

AHCPR Pub. No. 97-0026.

Cohen SB. The redesign of the Medical

Expenditure Panel Survey, a component of the DHHS

Survey Integration Plan. In: Proceedings of the Council

of Professional Associations on Federal Statistics

(COPAFS) Seminar on Statistical Methodology in the

Public Service. 1996 Nov; Bethesda (MD).

Cohen SB. Sample design of the 1996 Medical

Expenditure Panel Survey Household Component.

Rockville (MD): Agency for Health Care Policy and

Research; 1997a. MEPS Methodology Report No. 2.

AHCPR Pub. No. 97-0027.

Cohen SB. An evaluation of alternative PC-based

software packages developed for the analysis of

complex survey data. The American Statistician

1997b;51(3):285-292.

Cohen SB, Machlin SR. Characteristics of

nonrespondents in the MEPS Household Component.

Proceedings of the American Statistical Association.

Section on Survey Research Methods; 1998 Aug;

Dallas. Alexandria (VA): American Statistical

Association; 1998.

Cox BG, Cohen SB. Methodological issues for

health care surveys. New York: Marcel Dekker; 1985.

DiGaetano R, Goksel H. Internal report on factors

associated with MEPS Round 1 dwelling unit

nonresponse. Unpublished report. Rockville (MD):

Westat, Inc.; 1996.

Judkins D, Marker D, Waksberg J. National Health

Interview Survey: research for the 1995 redesign.

Unpublished report. Prepared under contract for the

National Center for Health Statistics. Rockville (MD):

Westat, Inc.; 1994.

Shah BV, Barnwell BG, Bieler GS, et al. Technical

manual: statistical methods and algorithms used in

SUDAAN release 7.0. Research Triangle Park (NC):

Research Triangle Institute; 1996.

StataCorp. Stata Statistical Software: Release 5.0.

College Station (TX): Stata Corporation; 1997.