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Sample Design of the 1996 

Medical Expenditure Panel Survey 

Nursing Home Component 

Methodolo 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 Nursing

Home Component produces national estimates of

insurance coverage and the use of services, expenditures,

and sources of payment for persons residing in or

admitted to nursing homes. The NHC also gathers

information on nursing home characteristics–such as

facility type, ownership, chain affiliation, certification,

facility size, and location–for a nationally representative

sample of nursing homes. This report documents the

implementation of the sample design for the MEPS

Nursing Home Component, including the sampling

frame, facility selection, and within-facility sample

selection through Round 1 of data collection.

Suggested citation

Bethel J, Broene P, Sommers JP. Sample design of the 1996 Medical

Expenditure Panel Survey Nursing Home Component. Rockville

(MD):Agency for Health Care Policy and Research; 1998. MEPS

Methodology Report No. 4. AHCPR Pub. No. 98-0042.

http://www http://www.ahcpr.gov/
Sample Design of the 1996 

Medical Expenditure Panel Survey 

Nursing Home Component 

U.S. Department of Health and Human Services

Public Health Service

Agency for Health Care Policy and Research

   yyyyy zzzz {{{{{ |||| Report 4

Methodolo Methodology 

AHCPR Pub. No. 98-0042

September 1998
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,
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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

(301/594-1406).
v

Table of Contents

Overview of Sample Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Sampling Frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Facility Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Sampling of Persons Within Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Tables

1. Person-level population estimates and relative standard errors for nursing and personal care homes:

1987 National Medical Expenditure Survey Institutional Population Component . . . . . . . . . . . . . . . . . . . . 2

2. Nursing and personal care facilities–number sampled and expected number responding by round:

1996 MEPS Nursing Home Component. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. Optimum allocation to cost strata based on the 1996 MEPS Nursing Home Component sample . . . . . . . 8

4. Minimum acceptable response rates for the 1996 MEPS Nursing Home Component . . . . . . . . . . . . . . . 12

5. Rules for facility sampling: 1996 MEPS Nursing Home Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6. Response rates at end of Round 1: 1996 MEPS Nursing Home Component . . . . . . . . . . . . . . . . . . . . . 15

Figures

1. First admissions eligibility determination using a single respondent:

1996 MEPS Nursing Home Component. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2. Final determination of eligibility for sampled nursing home residents:

1996 MEPS Nursing Home Component. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
vi
1

Overview of Sample Design

The goal of the Medical Expenditure Panel Survey

Nursing Home Component (MEPS NHC) is to produce

national estimates for persons residing in nursing homes

during 1996. Information was gathered on nursing home

characteristics for a nationally representative sample of

nursing homes and on the demographic characteristics,

residence history, health status, and long-term care

expenditures for a sample of residents in these nursing

homes. This report documents the implementation of the

sample design, including the sampling frame, facility

selection, and within-facility sample selection through

Round 1 of data collection.

The target population consists of freestanding nursing

homes with at least three beds staffed and set up for

nursing care, as well as nursing care units consisting of a

distinguishable group of three or more nursing home beds

within a larger facility. Either type of facility must be:

• Medicare certified as a skilled nursing facility and/or

Medicaid certified as a nursing facility, or

• Licensed as a nursing home with a registered nurse or

licensed practical nurse onsite 24 hours a day, 7 days a

week.

The sample of nursing home residents was stratified

by whether residents resided at the nursing home at the

beginning of 1996 (current-residents sample) or were

admitted during the calendar year (first-admissions

sample). The target population of the current-residents

sample consisted of persons who resided in nursing homes

as of January 1, 1996. The target population of the firstadmissions sample consisted of persons who resided in a

nursing home during 1996 but were not current residents

as defined above.

The sample was designed with the goal of estimating a

population proportion of 0.20 with a coefficient of

variation (CV) of 9.8 percent or less for facilities, 5.5

percent or less for current residents, and 6.5 percent or less

for first admissions. Table 1 shows the relative standard

errors for selected characteristics of current residents and

first admissions obtained in the 1987 National Medical

Expenditure Survey Institutional Population Component, a

similar previous survey conducted by the Agency for

Health Care Policy and Research (AHCPR). These

relative standard errors, or CVs, are based on a sample size

of approximately 800 responding nursing homes.

The sampling frame for the selection of facilities in the

MEPS NHC was an updated version of the 1991 National

Health Provider Inventory (NHPI). The 1991 NHPI is a

census of approximately 16,000 nursing homes in the

United States, collected by the Bureau of the Census for

the National Center for Health Statistics and AHCPR. The

1991 NHPI served as the base, and approximately 2,000

new facilities and 275 hospital-based facilities were added

to this original list to create the sampling frame.

Facilities were selected as a double, or two-phase,

sample. For the first phase, 1,651 facilities were sampled

within strata, with probabilities proportional to size. The

measure of size was the number of beds in the facility

reserved for nursing home use. The first-phase sample

was assigned to four strata based on expected survey travel

costs, and a second-phase subsample of 1,430 facilities

was selected with equal probabilities within these four cost

strata.

The second-phase sample was divided into a main

sample of 1,150 facilities and a reserve sample of 280

facilities, the latter being divided into four “release groups”

of 70 facilities each. The release groups were intended to

be sent to the field to supplement the main sample if

response and eligibility rates were lower than expected.

On the other hand, the main sample was randomly split

into 18 recall groups of approximately 64 facilities each.

If response and eligibility rates were higher than expected,

sampled facilities could be randomly withdrawn from the

field by canceling data collection in selected recall groups.

In fact, the MEPS NHC Round 1 response and eligibility

rates were higher than anticipated. Therefore, at the

conclusion of Round 1, the facilities in two randomly

selected recall groups were withdrawn from Rounds 2 and

3 of data collection.

Sample Design of the 1996 Medical Expenditure Panel Survey 

Nursing Home Component

by James Bethel, Ph.D., and Pamela Broene, M.S.,Westat, Inc., and John Paul Sommers, Ph.D.,

Agency for Health Care Policy and Research
2

Table 1. Person-level population estimates and relative standard errors for

nursing and personal care homes: 1987 National Medical Expenditure Survey

Institutional Population Component 

Sample and measure Estimate Relative standard error

Current residents

Average annual expenses $16,432 0.018

Per diem expenses $52.10 0.016

Average annual Medicaid expenses $8,236 0.040

Total days in facility 317.0 0.006

Proportion with dementia 0.133 0.024

Proportion needing help walking 0.700 0.014

Proportion white 0.910 0.008

First admissions

Average annual expenses $6,884 0.029

Per diem expenses $68.00 0.027

Average annual Medicaid expenses $2,016 0.077

Total days in facility 114.80 0.023

Proportion with dementia 0.063 0.040

Proportion needing help walking 0.754 0.017

Proportion white 0.906 0.011

Source: Agency for Health Care Policy and Research: 1987 National Medical Expenditure Survey.

In most facilities, a fixed sample of four current

residents and four new admissions was selected using

simple random sampling within the facility. In facilities

with measures of size that were poorly correlated with the

number of admissions, the first admissions sample size

could be increased from two to three per round (to a total

of six). The within-facility sample sizes are intended to

yield approximately 3,043 eligible current-resident

respondents and 2,218 eligible first-admission respondents,

all with complete use and expenditure data. The target

sample sizes are summarized in Table 2.
3

Table 2. Nursing and personal care facilities—number sampled and expected

number responding by round: 1996 MEPS Nursing Home Component

Units Round 1 Round 2 Round 3 Total

Facilities

Selected at first phase 1,651 — — —

Selected at second phase 1,150 — — —

Eligible 1,127 — — —

Completed FQ 862 — — —

Cooperated with sampling 836 811 787 —

Current residents

Selected and eligible 3,344 — — —

Unit response for IUED and RH data1 — 3,243 3,144 —

Completed IUED and RH data2 — 3,177 3,043 —

Completed background data 2,842 — — —

Completed baseline health status data 3,210 — — —

Completed end-of-year health status data — — 2,020 —

First admissions

Selected — 1,622 1,574 3,196

Not first admissions — 357 346 7 03

Eligible first admissions — 1,265 1,228 2,493

Unit response for IUED and RH data1 — 1,189 1,155 2,344

Completed IUED and RH data2 — 1,125 1,093 2,218

Completed background data — 1,037 1,007 2,044

Completed baseline health status data — 1,163 1,130 2,293

Completed end-of-year health status data — 397 673 1,070

1At least 1/3 of data completed.

2All data provided.

Note: FQ =Facility Questionnaire. IUED = institutional use and expenditure data. RH = residence history.

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component.
4

Sampling Frame

Description of the National Health

Provider Inventory

The MEPS NHC sampling frame was based on the

1991 NHPI. The U.S. Bureau of the Census collects the

NHPI for the National Center for Health Statistics

(NCHS) and AHCPR. In 1991, it contained

approximately 16,000 nursing homes and 31,000 boardand-care homes. The MEPS NHC sampling frame was

created by updating a subset of the 1991 NHPI provided

by NCHS to AHCPR. This subset contained 15,811

facilities on the 1991 NHPI that NCHS defined as

nursing homes, as well as 1,691 potential new nursing

homes that were identified through State lists and

directories of nursing homes (National Center for Health

Statistics, 1995). 

A nursing home, according to the NCHS definition,

is a facility having at least three beds and identifying

itself on the NHPI questionnaire as one of the following:

• A licensed nursing home;

• A skilled nursing long-term care unit of a hospital;

• A nursing care unit of a retirement center;

• A nursing facility certified under Medicare or

Medicaid; or

• Some other type of nursing home.

Among the 17,502 facilities on the basic frame, 205

appeared to be board-and-care homes, which do not

meet this definition and were excluded. Another 275

facilities that had been excluded by NCHS—mostly

Department of Veterans’Affairs (VA) facilities—were

added to the frame. The final updated NHPI contained

17,572 (17,502 − 205 + 275) facilities (Pancholi, 1995).

To be eligible for the MEPS NHC, facilities must

have at least three beds and be either Medicare- and/or

Medicaid-certified or licensed as nursing homes. Final

eligibility for the MEPS NHC was determined during

Round 1 of facility data collection; however, the initial

sampling frame included all facilities on the updated

NHPI that were likely to meet these criteria.

Editing the MEPS NHC Frame

The number of beds reported by the facility on the

NHPI questionnaire was edited for hospital-based

facilities using information in the AHA Guide

(American Hospital Association, 1993). As part of the

editing, the number of beds was compared with the

number of residents. A large ratio of residents to beds

could indicate an inconsistency in reporting, unless the

questionnaire shows the presence of a long-term care

unit within a larger facility for the elderly. As a result,

the number of beds was edited for 209 hospital-based

facilities.

Missing values for variables on the NHPI that were

needed for sampling were obtained from external

sources when possible. Information on

license/certification status, type of ownership, and the

number of beds was obtained for all but a small

percentage of the new facilities. Certification status was

not available for the 275 VA facilities and was imputed

for an additional 69 facilities. The facility ownership

type (profit, nonprofit, government) was unknown for

216 facilities but was not imputed. Missing telephone

numbers were supplied for over 1,700 facilities, but 132

still remained missing on the frame at the time of

sampling. A Beale code (also known as the Human

Resource Profile Code) was placed on the file to

indicate the metropolitan statistical area (MSA) status of

each facility. These codes were collapsed for use in

sampling. The collapsed values were 0 = large

metropolitan core, 1 = large metropolitan fringe, 2 =

medium metropolitan area, 3 = lesser metropolitan area,

4 = adjacent to an MSA, and 5 = not adjacent to an

MSA. 

Measure of Size

In the initial survey planning, the number of

residents was proposed as the most appropriate measure

of size. A careful review of the data fields on the NHPI,

however, indicated that the number of “eligible beds”

would be preferable. The question on the NHPI

concerning the number of residents is somewhat general

(“How many residents stayed in this home last night?”).

In contrast, the question concerning the number of beds

defines certain types of beds that should be excluded
5

(e.g., beds for day care only and hospital or retirement

center beds not associated with the nursing home). Also,

the number of residents might be construed to include

persons in a board-and-care wing. Therefore, the

number of beds as reported on the NHPI questionnaire

was used directly as the measure of size except for the

209 cases where the number of beds was edited using

the 1993 American Hospital Association Guide

(American Hospital Association, 1993).

Facility Selection

Summary

Facilities were selected in two phases. In the first

phase, a stratified sample of 1,651 facilities was selected

with probability proportional to size. Six of the seven

strata were created by crossing three types of

Medicaid/Medicare reimbursement with an indicator of

whether the facility was hospital based or not. The

seventh stratum contained the 20 largest facilities, of

which 11 had been chosen by NCHS for inclusion in the

NCHS National Nursing Home Survey (NNHS) and the

remaining 9 were designated for the MEPS NHC.

These nine facilities were then drawn with certainty in

the first phase of the MEPS NHC. The stratum sample

sizes in the remaining six strata were determined using

proportional allocation. The original measure of size

was the number of beds, but to minimize overlap with

the NCHS NNHS, a Keyfitz procedure was employed to

compute new conditional probabilities of selection. 

Cost stratification was then performed on the 1,651

facilities in the first-phase sample, with the actual strata

being defined in terms of distance from the nearest of

the 50 largest U.S. cities and the expected effect on

survey travel costs. Next, the optimal sampling rates

were determined for these four cost strata. Using the

sampling rates, a cost-stratified subsample of 1,430

facilities was selected from the 1,651 facilities in the

main sample. Within each cost stratum, the secondphase sample of facilities not drawn with certainty

(noncertainty facilities) was subsampled at a rate of .803,

yielding a reserve sample of 280 facilities and a

remaining main sample of 1,150 facilities. The four

release groups were assigned by sorting the reserve

sample by order of selection and consecutively

numbering from 1 to 4, repeating until all 280 facilities

were assigned. This resulted in four release groups of 70

facilities each. The main sample was randomly divided

into 18 subsamples of approximately 64 facilities each

by sorting the noncertainty sample facilities in the order

of selection and consecutively numbering from 1 to 18,

repeating until all 1,139 noncertainty facilities were

assigned.

Initial Stratification

The facility sample was a two-phase stratified

sample. In the first phase, the 17,572 facilities in the

frame were stratified into seven strata. Facilities were

selected with probabilities proportional to size (i.e., the

number of eligible beds) in each stratum in the first

phase. This initial sample was grouped into the four cost

strata described above. In the second phase,

noncertainty facilities were subsampled with equal

probabilities within each cost stratum.

The first-phase strata were formed by grouping

facilities according to three types of Medicaid/Medicare

reimbursement and whether the facility was hospital

based or not. The 20 largest facilities were placed in a

separate stratum. Eleven of these had been selected

previously for the NNHS, conducted by the NCHS. The

remaining nine were designated for the MEPS NHC. 

Determining Selection Possibilities

An initial sample of 1,651 facilities was selected

using probability proportionate to size (PPS) sampling,

with the number of nursing beds as the measure of size.

Using this technique, the number of facilities allocated to

each of the original strata was proportional to that

stratum’s number of the total number of nursing beds.

For the ith facility in the hth stratum, the initial selection

probability was computed as:

Phi = nh

= (1,651)

= (1,651) Facility i MOS

Total MOS

Facility i MOS

Stratum h MOS

Stratum h MOS

Total MOS

Facility i MOS

Stratum h MOS
6

However, before the sample was selected, these

selection probabilities were modified to minimize

overlap with the 1995 NNHS, which was conducted by

NCHS and fielded in late 1995. Because the NNHS and

MEPS NHC used similar sampling frames, it was

important to prevent (if possible) any nursing homes

from being included in both surveys.

A Keyfitz procedure was used to adjust the

probabilities of selection to minimize this overlap. This

procedure provides the desired unconditional

probabilities of selection for the MEPS NHC sample

while at the same time minimizing the overlap. To

compute conditional probabilities of selection for the

MEPS NHC, the probabilities of selection for a facility

in both the MEPS NHC and the 1995 NNHS frame, as

well as which nursing homes were selected in the 1995

NNHS, must be known. The following notation

describes the procedure.

P(i∈ MEPS NHC) = Probability that the ith nursing home in the NHPI is selected for 

the MEPS NHC

P(i∈ NNHS) = Probability that the ith nursing home in the NHPI is selected for 

the 1995 NNHS

P(i∈ MEPS NHC  i∈ NNHS) = Conditional probability that the ith nursing home is selected for 

the MEPS NHC given that it was selected for the 1995 NNHS

The unconditional probability of selection for a facility in the MEPS NHC can be written as:

P(i∈ MEPS NHC) = P(i∈ MEPS NHC | i∈ NNHS) P(i∈ NNHS) + P(i∈ MEPS NHC | i∉ NNHS) P(i∉ NNHS). 

From this statement, expressions for the conditional probabilities of selection P(i∈ MEPS NHC | i∈ NNHS) and

P(i∈ MEPS NHC | i∉ NNHS) for the facilities on the MEPS NHC frame can be derived. The actual conditional

probabilities of selection for the MEPS NHC depend on which of the two situations described below applies.

Case 1: P(i∈ MEPS NHC) ≥ 1 − P(i∈ NNHS). For this case, set

P(i∈ MEPS NHC  i∈ NNHS) = 

and

P(i∈ MEPS NHC  i∉ NNHS) = 1

Case 2: P(i∈ MEPS NHC) < 1 − P(i∈ NNHS). Here, set

P(i∈ MEPS NHC  i∈ NNHS) = 0

and

P(i∈ MEPS NHC | i∉ NNHS) = P(i∈ MEPS NHC)

1 − P(i∈ NNHS)

P(i∈ MEPS NHC) − (1 − P(i∈ NNHS))

P(i∈ NNHS)
7

For Case 1,

P(i∈ MEPS NHC) = P(i∈ NNHS)

+ 1 ∗ (1 − P(i∈ NNHS)) = P(i∈ MEPS NHC)

For Case 2,

P(i∈ MEPS NHC) = 0 ∗ P(i∈ NNHS) + ∗ (1 − P(i∈ NNHS)) = P(i∈ MEPS NHC) P(i∈ MEPS NHC)

1 − P(i∈ NNHS)

P(i∈ MEPS NHC) − (1 − P(i∈ NNHS))

P(i∈ NNHS)

After these rules were applied in the six noncertainty

strata, the facilities were selected for the MEPS NHC

using the redefined selection probabilities. Selection

was done using a systematic selection process. For this

selection the file was sorted by Beale code and

ownership to create implicit sampling strata within each

of seven explicit strata. In the certainty stratum, the nine

facilities not selected for the NNHS sample were

sampled with certainty. The remaining 11 facilities were

assigned a zero probability of selection. The outcome of

using these probabilities of selection was that none of the

MEPS NHC sample facilities overlapped with the

NNHS sample.

Two additional certainty facilities were selected in

two of the noncertainty strata. These two facilities were

Case 1 situations and were not selected in the NNHS

sample, so their Keyfitz probabilities were set equal to

one. The remainder of the sample in the six noncertainty

strata were Case 2 facilities.

Cost Stratification

After the first-phase sample was drawn, the sampled

facilities were assigned to four cost strata based on the

geographic distribution of the sample. The cost strata

were approximated by measuring distance in kilometers

from the nearest of the 50 largest U.S. cities.

Specifically, each facility was assigned to one of four

cost strata:

• Stratum 1: Full workload in a single geographic area,

such as a city.

• Stratum 2: Partial workload only in a single area,

requiring considerable travel.

• Stratum 3: Single facility requiring considerable

travel but within the range of other facilities.

• Stratum 4: Single facility at a distance requiring air

travel.

The cost stratification process consisted of several

steps. The first-phase sample of 1,651 facilities was

mapped using computer mapping software. Next, each

facility was mapped into the appropriate ZIP Code

center point. Then, to approximate the cost strata, a map

of the 50 largest U.S. cities and concentric zones around

them was overlaid on the facility map. Facilities located

within 100 kilometers of a city were assigned to Stratum

1; facilities 100-200 kilometers, to Stratum 2; facilities

200-300 kilometers, to Stratum 3; and facilities beyond

300 kilometers of a city, to Stratum 4.

Minimizing Overlap With the

Medicare Current Beneficiary Survey

The Medicare Current Beneficiary Survey (MCBS)

is an ongoing survey of Medicare beneficiaries

conducted by Westat for the Health Care Financing

Administration. As part of this survey, Westat field

interviewers visit many nursing homes throughout the

United States. As with the NNHS, it was important to

minimize the number of nursing homes involved in both

surveys. However, an alternative to the Keyfitz

procedure was necessary because of the virtual

impossibility of calculating the probabilities of selection

for the MCBS facilities.

The procedure used was to flag any nursing home

that MCBS respondents reported as their current

residence as of September 28, 1995, and that was also in

Given the outcome of the 1995 NNHS sampling, it

is shown below that selecting the MEPS NHC sample

with these redefined probabilities preserves the original

MEPS NHC probabilities of selection. 
8

Table 3. Optimum allocation to cost strata based on the 1996 MEPS Nursing

Home Component sample

Cost per First-stage Second-stage Optimal Reserve 

Stratum facility Wh sample sample sampling rate Main sample sample

1 $2,216 0.52 855 765 0.894 616 149

2 $2,583 0.26 439 363 0.827 292 71

3 $2,335 0.16 255 222 0.872 178 44

4 $2,949 0.07 102 80 0.781 64 16

Total — — 1,651 1,430 — 1,150 280

Note: The stratum proportions are based on the MEPS Nursing Home Component sample. Costs are based on the data

collection budget for the MEPS Nursing Home Component and include travel costs, interviewer per diem and salary, and data

processing costs. Based on proximity to large U.S. cities, the strata were defined as follows: Stratum 1—Full workload in a

single geographic area, such as a city. Stratum 2–Partial workload only in a single area, requiring considerable travel. Stratum

3–Single facility requiring considerable travel but within the range of other facilities. Stratum 4–Single facility at a distance

requiring air travel.

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component.

the first-phase MEPS NHC sample. There were 71 such

facilities. Of these overlapping facilities, one MEPS

NHC noncertainty facility was removed from the firstphase sample prior to sampling in the second phase, thus

giving a zero chance of selection. An adjustment factor

was applied to the weights within each cost stratum to

prevent an undercoverage bias. The nine facilities that

were included with certainty in the first phase of MEPS

NHC sampling were designated to be selected with

certainty in the second phase, regardless of whether they

overlapped with the MCBS. Based on opinions of health

care analysts at AHCPR, facilities excluded in this way

were unlikely to differ in any systematic way from other

facilities in the first-phase sample. Thus, this procedure

was not expected to cause any sampling bias.

Selecting the Second-Phase Sample

An equal probability subsample of the initial sample

was drawn within each cost stratum using systematic

sampling. The sample size for each cost stratum was

determined by optimum allocation. The optimum

allocation was computed using the formula

nh = n 

Σ

W

(W

h /

k /

√

√

ch

ck)

nrh

k

where Wh and rh represent the population proportion and

sampling rate for the hth stratum. This formula neglects

the variance for the analysis variables, since it is

expected that they would vary little between cost strata.

The MEPS NHC facilities overlapping with MCBS were

not removed prior to determining the optimal allocation,

since these facilities will be treated in sample weighting

as nonrespondents.

The optimum allocation based on the MEPS NHC

first-phase sample is shown in Table 3. The optimal

subsampling rates ranged from .78 to .89. The

proportions (Wh) shown in Table 3 are those obtained in

the MEPS NHC sample of 1,651 facilities. The data

collection cost estimates include travel costs, interviewer

per diem and salary, and data processing costs.
9

Sampling Algorithms

This section describes in detail the algorithms used to select the main and reserve samples. The following

notations are used in this section:

S0 = event the facility is selected for the first-phase sample

S1 = event the facility is selected for the second-phase sample

n0 = overall first-phase sample size 

nh0 = first-phase sample size in stratum h

n1 = overall second-phase sample size

nh′1 = second-phase sample size in cost stratum h′

m = overall main sample size

mh′ = main sample size in cost stratum h′

r = overall reserve sample size

rh′ = reserve sample size in cost stratum h′

ch0 = number of first-phase certainty selections in stratum h

ch′1 = number of second-phase certainty selections in cost stratum h′

Mhi = measure of size for ith facility in stratum h

Nh = number of facilities on the frame in stratum h

π = initial selection probability for ith facility in stratum h

π = final selection probability for ith facility in stratum h (1)

hi

(0)

hi
10

First-Phase Sample

Both phases of the facility sampling were

accomplished using Westat’s macro WESSAMP.

Probability proportional to size (PPS) systematic

sampling was used in the first phase, and equal

probability systematic sampling in the second phase. In

the first phase, the unconditional probability of selection

for the ith facility was nhMhi / Mh, where Mhi is the

measure of size for the ith facility in stratum h (h =

1,2....7), Mh is the sum of the measures of size in the

stratum, and nh is the number of facilities sampled in

the stratum. Any facility with unconditional probability

of selection greater than or equal to 1 was classified as a

certainty selection and assigned a selection probability

equal to 1. Two facilities in the six noncertainty strata

met this criterion. In the certainty stratum, there were

20 large facilities, of which 9 were not sampled in

NCHS’s NNHS. These were taken with certainty for the

MEPS NHC. In the large stratum, the remaining 11

facilities had their conditional probabilities set to 0. In

the six noncertainty strata, these selection probabilities

were modified to minimize overlap with the NNHS, as

described previously. The modified probabilities of

selection resulted in two additional facilities being

selected with certainty.

Thus the sampling algorithm for the first phase

consisted of this step:

Step 1. Within each stratum, sort the facilities by

Beale code, type of ownership, and ZIP Code.

Calculate the conditional (Keyfitz) probabilities of

selection. Select nh0 facilities with PPS, with the

Keyfitz probability of selection as the measure of size.

There will be ch0 certainties, i.e., facilities that will have

π = 1. For the other facilities, the original

unconditional selection probabilities will be

π = 

where Mhi is the measure of size for the ith facility in

the hth stratum.

Second-Phase Sample

The first-phase sample of 1,651 facilities was

mapped into four cost strata and subsampled within

each cost stratum. The sample size in each cost stratum

was determined using optimal allocation. Equal stratum

variances were assumed for MEPS NHC variables.

Within each cost stratum, the certainty facilities and

noncertainty facilities identified as overlapping with

MCBS were first removed. The sample was then sorted

by the same order of selection used in the first-phase

sample, and an equal probability systematic sample of

facilities was drawn with the sample sizes shown in

Table 3. The resulting second-phase sample of 1,430

facilities was again sorted within cost strata by the order

of selection, and the noncertainty facilities were

subsampled again at a rate of .803 to create a randomly

chosen reserve sample of 280 facilities and a main

sample of 1,150 facilities. The reserve sample was split

into four release groups of 70 facilities each by

sequentially assigning the numbers 1 through 4 to the

facilities in their original sort order. Using the same

procedure, the noncertainty facilities in the main sample

were randomly divided into 18 recall groups consisting

of approximately 64 facilities each.

Thus the sampling algorithm for the second phase

consisted of these steps:

Step 2. Map the sample of n0 facilities into the

four cost strata using facility ZIP Code and mapping

software.

Step 3. Remove noncertainty facilities identified as

overlapping with MCBS and certainty facilities from the

first-phase sample.

Step 4. To select the second-phase sample of n1

facilities from the first-phase sample of n0, sort the

facilities in each cost stratum in the original order of

selection. Within each cost stratum, draw an equal

probability systematic sample of facilities, where the

sample size is determined by optimum allocation. (See

Table 3.) Subtract the number of first-phase certainty

facilities in each cost stratum from the designated

sample size in Table 3 prior to sampling.

(nh0 − ch0) Mhi

Nh − ch0

(0)

hi

Σ Mhi

(0)

hi

i=1
11

Step 5. To select the reserve sample of r facilities

from the n1 second-phase facilities, first sort the

noncertainty facilities in the second-phase sample by

order of selection in each cost stratum. Within each cost

stratum, select an equal probability systematic sample of

facilities using the sample sizes in Table 3. Create four

release groups by sorting the reserve sample in the order

of selection, then consecutively numbering the reserve

sample from 1 to 4, repeating until the entire reserve

sample has been assigned. There will be m = n1 − r

facilities in the main sample and r facilities in the

reserve sample. The reserve sample will consist of four

release groups of r/4 facilities each.

Step 6. To create the 18 recall groups from the

main sample, sort the noncertainty facilities in the main

sample in the order of selection, then consecutively

number facilities from 1 to 18, repeating until all

noncertainty main sample facilities have been assigned.

Each recall group thus will represent a random

subsample of the main sample.

For a two-phase sampling process like this, the

sampling probabilities for the ith facility in the hth

stratum can be written as:

π = P (hi∈S1 | hi∈S0) P (hi∈S0).

For the “initial certainty/final certainty” facilities—

facilities that were selected with certainty in both the

first and second phases of sampling—the overall

selection probability is 1.00.

For the “initial noncertainty/final noncertainty”

facilities, the final selection probability would be:

π =

where mh′ is the main sample size in cost stratum h′ and

nh′0 is the number of first-phase sample facilities in cost

stratum h′. If release groups are used, the numerator in

the first factor is increased by the extra number of

facilities released. If no release groups are used but

some recall groups are withdrawn, the numerator is

decreased by the number of facilities being withdrawn

in cost stratum h′.

Initial Screening of Facilities

An initial screening was carried out by telephone.

Only facilities meeting the following requirements were

retained in the sample:

• Facilities must have three or more beds that are

staffed and set up for residents (or a distinguishable

group of three or more beds within a facility).

• Facilities must either be:

- Medicare certified as a skilled nursing facility

and/or Medicaid certified as a nursing facility,

or

- Licensed as a nursing home with a registered

nurse or licensed practical nurse onsite 24 hours

a day, 7 days a week.

As a result of the screening, 14 facilities were identified

as being out of business and 1 facility was determined

to be ineligible.

Round 1 Facility Response Rates

Given the response rate assumptions specified in

Table 4, the initial sample sizes were intended to result

in a final sample of approximately 787 cooperating

facilities, with control over the final sample size to be

obtained through the use of release and recall groups.

At the end of Round 1, 1,124 of the 1,150 facilities

fielded for data collection were determined to be

eligible. Of these, 951 completed the Facility

Questionnaire and sampling of current residents, 158

refused, and 14 broke off the interview. Twelve facilities

were ineligible and 15 had gone out of business. The

Round 1 response rate to the Facility Questionnaire was

85 percent and the eligibility rate was 98 percent, both

exceeding expectations. Based on these data, AHCPR

made a decision to recall two groups of facilities,

totaling 127 facilities, from Rounds 2 and 3 of data

collection. Of these, 108 had cooperated in Round 1.

(nh0 − ch0) Mhi

Nh− ch0

(1)

hi

(1)

hi

Σ Mhi i=1

mh′

nh′0
12

Table 4. Minimum acceptable response rates for the 1996 MEPS Nursing

Home Component

Instrument Response rate Method of calculation

Facility Questionnaire (FQ) 77% Responding facilities

Selected eligible facilities

Jan. 1, 1996,sampling list 98% Facilities completing sampling

Facilities completing FQ

Round 2 admissions sampling list 97% Facilities completing sampling

Facilities cooperating on previous contacts

Round 3 admissions sampling list 97% Facilities completing sampling

Facilities cooperating on previous contacts

Institutional use and expenditure data 91% Sampled persons with complete institutional 

(Jan. 1, 1996,residents) use and expenditure data for all of 1996/All 

sampled and eligible Jan. 1, 1996,residents

Institutional use and expenditure data 89% Sampled persons with complete institutional

(first admissions) use and expenditure data for all of 1996/All 

sampled and eligible first admissions

Residence history data 95% Sampled persons with complete residence history 

(Jan. 1, 1996,residents) data for all of 1996/All sampled and eligible 

Jan. 1, 1996,residents

Residence history data 90% Sampled persons with complete residence history

(first admissions) data for all of 1996/All sampled and eligible

first admissions

Background data 85% Sampled persons with data/All sampled and eligible 

(Jan. 1, 1996,residents) January 1, 1996,residents

Background data (first admissions) 82% Sampled persons with data/All sampled and eligible

first admissions

Baseline health status data 96% Sampled persons with data/All sampled and eligible 

(Jan. 1, 1996,residents) Jan. 1, 1996,residents

Baseline health status data 92% Sampled persons with data/All sampled and eligible 

(first admissions) first admissions

End-of-year health status data 91% Sampled persons with data/All sampled and eligible 

(Jan. 1, 1996,residents) Jan. 1, 1996,residents residing in an eligible facility 

on Dec. 31, 1996

End-of-year health status data 89% Sampled persons with data/All sampled and eligible

(first admissions) first admissions residing in an eligible facility on

Dec. 31, 1996

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component.
13

Field Problems

Nursing Homes Associated With Other

Facilities

Sampled facilities belonging to nursing home

chains were identified before screening to assist both

the recruiters and Round 1 interviewers. Facilities that

were affiliated with hospitals or retirement centers and

facilities with board-and-care wings were also given

special attention during the training of field staff.

During Round 1 facility data collection, if the facility

respondent identified the facility or unit as a hospitalbased skilled nursing facility, the hospital name was

added to the place roster in the Facility Questionnaire

and a flag was set to indicate that the hospital has a

skilled nursing facility unit. Interviewers were

instructed to carefully identify and list residents only of

those parts of the facility that were eligible for the

MEPS NHC. 

Facilities That Moved or Combined With Other

Facilities

During screening it was discovered that some

facilities were no longer located at the address given for

them in the NHPI. Facilities that had moved were

retained in the sample and followed to the new location.

If the new location was not learned until fieldwork was

underway, the facility was assigned to a new interviewer

if necessary to complete data collection.

A sampled facility that combined with another

facility was retained in the sample as long as the other

facility was not listed in the NHPI. If both of the

original facilities were listed separately in the NHPI, the

combined facility had an increased chance of selection

because it could have been selected through either one

of the original facilities. Either this increased chance of

selection had to be accounted for in the facility weight

or, alternatively, one of the listings had to be considered

out of scope. When the combined facilities could be

treated as multiple units of one nursing home, the latter

approach was used. Otherwise, weighting adjustments

were made.

Facilities With Multiple Units

When the Facility Questionnaire was administered,

the sampled facility was sometimes discovered to

correspond to more than two eligible facilities or to a

facility with more than one unit containing eligible

nursing home beds. If any of the facilities (or units of

one facility) associated with the sampled facility were

listed separately in the NHPI frame, they were

considered out of scope because they had already had a

chance to be selected. Thus, each facility had only one

chance of selection, thereby avoiding the need to make

an adjustment to the facility base weight for multiple

chances of selection. If none of the nursing homes

associated with the sampled facility were listed in the

frame, the interviewer was instructed to collect data

from all of them if time and travel distance permitted.

If this was not practical, the plan was to subsample in

facilities that contained three or more eligible units or

locations where there were too many units to permit

data collection from all of them. However, during

Round 1 it was not necessary to do this. An alternative

plan was to assign some of the units to another

interviewer. The rules for deciding which units were

eligible are given in Table 5.

Survey Database

A database of the sampled facilities was created and

loaded into each computer-assisted personal

interviewing (CAPI) machine for the field staff to use in

the sampling of residents. Each record contained the

following data:

• Facility name, address, and telephone number;

• Numbers of residents and eligible beds from the

NHPI;

• Final measure of size;

• The random numbers used for sampling current

residents and first admissions.
14

Sampling of Persons Within

Facilities

The sample of nursing home residents consisted of

samples of persons who resided in institutions on

January 1, 1996 (the 1996 current residents sample) and

persons who were admitted to institutions at any time

from January 1 through December 31, 1996 (the firstadmissions sample). The subset of admissions being

admitted to a nursing home for the first time in 1996

constituted the eligible first-admissions sample. A more

detailed definition of an eligible first admission is given

later. The current-residents and first-admissions

samples cover the entire population of persons residing

in nursing homes during 1996. After all three rounds,

the target sample sizes of residents for the 787

cooperating facilities were 3,043 eligible current

residents and 2,218 eligible first admissions with

complete expenditure and residence history data. These

target sample sizes resulted from the number of

sampled persons with complete use and expenditure

data that were expected after sampling four current

residents and four to six first admissions per facility.

Two to three first admissions per facility in each of

Rounds 2 and 3 were sampled. A fixed sample size per

facility was chosen instead of sampling from each list at

a fixed rate because the former method is more reliable

for obtaining the desired sample sizes. As a

consequence, however, the first-admissions sample

weights are not equal across sampling periods, nor are

they exactly equal across nursing homes. To lessen the

variability of the first-admissions sampling weights, the

sample size is permitted to range from 2 to 3.

Checking Facility Data Against

Frame Data

The following procedure was implemented by the

field interviewers during their visits to the sample

institutions in Round 1. During the first visit to the

facility, the interviewer made a list of eligible current

residents. The interviewer entered the number of

current residents on the list into the CAPI system. The

computer compared the number of residents listed with

the measure of size derived from the NHPI and

displayed the message “Call Home Office” if any of the

following were true for r1, the number of eligible beds

listed in the NHPI, or r2, the number of current

residents listed at the facility:

Table 5. Rules for facility sampling: 1996 MEPS Nursing Home Component

Sampled unit

Listed in updated National 

Health Provider Inventory Headquarters One of subunits

Headquarters and all subunits None are eligible Only sampled subunit is eligible

Headquarters only All are eligible —

All subunits but 

not headquarters — Only sampled subunit is eligible

Subset of subunits is listed; Sampled unit and unlisted 

headquarters not listed — subunits are eligible1

Headquarters and subset Unlisted subunits

of subunits are listed are eligible Only sampled subunit is eligible

1Either revise computer-assisted personal interviewing (CAPI) to subsample or review in home office for weighting

corrections.

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component.
15

• r2 < 10 and  r1 − r2  > 5;

• 10 ≤ r2 ≤ 300 and r2/r1 > 1.5 or r2/r1 < .5; or

• r2 > 300 and r2/r1 > 1.33 or r2/r1 < .67.

If the nursing home facility existed within a longterm care facility, the interviewer verified that the

number of residents listed corresponded to the eligible

portion of the facility. The interviewer also verified that

no eligible portions of the facility were overlooked.

Current-Residents Sample

The interviewer compiled a list of current residents

as of January 1, 1996, in each sampled facility. Within

each facility, a systematic random sample of four current

residents was drawn within the CAPI system. The

within-facility sampling fraction was assigned to be

4/CRhi, where CRhi is the number of current residents

listed at the ith facility in the hth stratum, so that the

overall probabilities of selection of current residents

within strata were as close to equal as possible. The

probabilities of selection were not exactly equal because

the measure of size used to select facilities was the

number of beds; however, to the extent that the number

of current residents was correlated with the number of

beds at the facility, the selection probabilities were

approximately equal. In facilities with fewer than four

residents, the sampling fraction was set to one and all

residents were included. 

The interviewer entered the size of the list of current

residents in the CAPI system, which then determined the

random start, the skip interval, and the sample of line

numbers. The selected line numbers were displayed on

the computer screen and stored in memory for later

validation. The order of selection for the sampled

current residents was stored for inclusion in the final

database. At the end of Round 1, the response rates

shown in Table 6 were obtained for current residents.

The overall response rate for the current-residents

sample is 98.8 percent. Sampled residents needed to

have 75 percent of their baseline health status items

complete and age, sex, and race reported in order to be

considered respondents. Forty-four eligible current

residents did not meet this requirement. Of these, four

met the baseline health status criteria but were missing at

least one of the demographic variables. In addition, 17

sampled persons were ineligible.

Table 6. Response rates at end of Round 1: 1996 MEPS Nursing Home

Component

Completed Partial response Nonresponse

Questionnaire module Number Percent Number Percent Number Percent

Residence history 3,725 98 22 1 44 1

Background 3,621 96 13 0 157 4

Income/assets — — — — — —

Health insurance 3,545 94 38 1 208 5

Baseline health status 3,751 99 10 0 30 1

Prescribed medicines 3,584 95 145 4 62 2

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component. 
16

π = (Facility sample size) 

where 

Facility sample size = the number of facilities sampled;

FA sample size = the number of first admissions sampled at the given facility; 

Number of FAs = the number of first admissions listed at the given facility; 

Facility MOS = the number of nursing home beds on the frame for the facility; and

Total MOS = the total number of nursing home beds for facilities on the frame.

In order to have an approximately self-weighting sample:

π = 

Thus, in order to have equal selection probabilities, the FA sample size should be:

FA sample size =

=

=

= (Average FA sample size)

where

ρ = = Average FAs

Average MOS

Total FAs

Total MOS

Number of FAs listed

ρ(Facility MOS)

Number of FAs listed

Facility MOS

Total MOS

Total FAs

Overall FA sample size

Facility sample size

Number of FAs listed

Facility MOS

Total MOS

Facility sample size

Overall FA sample size

Total FAs

Number of FAs listed

Facility MOS

π (Total MOS)

Facility sample size

Overall FA sample size

Total FAs

FA sample size

Number of FAs listed

Facility MOS

Total MOS

First-Admissions Sample

First-Admissions Sample Size

Lists of residents were obtained from the sampled

facilities and screened to determine who had been newly

admitted since the last round of data collection. Listing,

sampling, and data collection for first admissions took

place in Rounds 2 and 3. The reference period for

Round 2 was from January 1 to June 30, 1996, and the

reference period for Round 3 was from July 1 to

December 31, 1996. The first admissions were

systematically sampled in the same manner as the

current-residents sample, except that the sample size was

determined in the CAPI program. The order of selection

for each sampled first admission was stored within the

program. If the measure of size differed substantially

from the number of current residents listed, then the

first-admissions sample probabilities of selection would

have led to excessive variability in the first-admissions

sampling weights if not corrected.

Thus, the sample size for the first-admissions

sample at a given facility may be revised based on the

relationship between the current residents and the

number of first admissions listed. The revised sample

size was based on the selection probability:
17

Thus, the first-admissions sample sizes were

adjusted upward or downward according to whether

more or fewer were listed, based on the measure of size

adjusted by the factor ρ to reflect the average number of

first admissions to residents. However, the withinfacility first-admissions sample size was not permitted to

exceed three per round, and was less than two only when

there were fewer than two first admissions in the facility

for the round. Although ρ is unknown, it can be

approximated using 1987 NMES data on the ratio of

nursing home admissions to residents. The value of ρ

using 1987 NMES data turns out to be

718,670/1,523,540 = .472 (Agency for Health Care

Policy and Research, 1990).

Eligibility Determination

Since residents could be admitted to a facility more

than once during the course of the reference period,

more than one record may have existed for some persons

on the facility’s list. Interviewers deleted duplicates so

that no individual appeared on the list more than once.

The interviewer then selected two or three first

admissions per facility per round of data collection,

using the CAPI software in the same manner as for

current residents.

An eligible first admission is defined as a person

with no admissions or stays on or after January 1, 1996,

in MEPS NHC-eligible facilities prior to the admission

for which the person was sampled at the primary

sampled facility. Information about where the person

lived from January 1, 1996, until the date of admission

to the sampled facility, referred to as the pre-stay period,

was collected from facility respondents. Using CAPI,

data were collected on the beginning and ending dates

for each separate period of residence during the pre-stay

period, the name and type of each place where the

sampled person stayed, and whether the person stayed at

that place the whole time between the beginning and

ending dates. Place types include the sampled facility,

community residence, acute care or long-term care

hospitals, and other long-term facilities. All places of

residence provisionally identified as long-term care

facilities were searched on the NHPI file for a

determination of nursing home eligibility status. Since

this would include hospitals with long-term care skilled

nursing units, the AHA file also was searched during

residence history data collection to determine firstadmission eligibility.

As an aid in determining eligibility, the NHPI and

AHA list (American Hospital Assocation, 1993) were

loaded into the interviewers’ laptop computers and

incorporated into their CAPI software. A search

software program allowed the field interviewers to

search for an identified long-term care facility on the

NHPI or AHA files in different ways, including name,

address, State, and telephone number. Interviewers were

able to conduct searches based on portions of the

information to maximize the likelihood of finding

matches. At the conclusion of the pre-stay residence

history data collection, the CAPI system automatically

brought the interviewer to the NHPI and AHA search

functions to search for matches to reported long-term

care facilities. Interviewers were trained to search for

the facility name and, if that failed, to use the facility

address and telephone number. Statisticians could verify

NHPI and AHA searches at any time in the home office. 

Based on information collected from the facility

about prior admissions to other facilities, the sampled

admissions were classified as eligible (with no prior stay

in an eligible facility during the reference period),

ineligible (with one or more prior stays identified), or

indeterminate (with some period of time within the

reference period for which the facility could not report

whether the resident was in an eligible facility).

Figure 1 shows the data collection process and the

flowchart for determining eligibility. There were four

possible outcomes, each having a different protocol for

data collection:

• Eligible first admission: No admissions prior to

sampling.

- All data collection continues.

• Ineligible first admission: One or more admissions

prior to sampling.

- All data collection stops.

• Provisionally eligible first admission: Eligibility

cannot be determined because either the facility has

a gap in the pre-stay data or there was an admission

to a facility but the name of the facility is unknown

or it did not match the NHPI listing.
18

Is facility flagged for

NHPI search? 

Start

Sufficient

information to

search NHPI?

Was stay in a 

place in the NHPI

Was person in a

nursing home 

unit?

Ineligible

(IF)

Missing dates in

pre-stay data?

Eligible

(IF)

Provisionally

eligible

(PF)

Attempt data

retrieval

Review in 

home office for final

determination

Another prior

stay?

Yes No

No

No

No

No

No

No

Yes

Yes

No

Yes

Yes

Yes

Yes

Figure 1. First admissions eligibility determination using a single

respondent: 1996 MEPS Nursing Home Component.

Note: EF=eligible first admission. IF=ineligible first admission. NHPI=National Health Provider Inventory. PF=provisionally eligible first admission.

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component.
19

- All data collection continues.

• Sampling error: The sampled admission is listed

twice and the entry sampled is the second one.

- All data collection stops.

For persons who were eligible or indeterminate,

interviewers attempted to complete a community

residence history for the pre-stay period by telephoning a

knowledgeable community respondent (usually a

relative). Information from the community residence

history questionnaires was consulted to make an

eligibility determination for persons in the indeterminate

group. Persons found to be ineligible on the basis of

either the facility data or the community data were

dropped from further data collection.

The process to determine eligibility was the same

for both the facility and the community pre-stay data.

Figure 2 shows the rules used to make a final eligibility

determination. This process was implemented if

determinations of eligibility were made using data from

both the facility and community respondent. Table 2

shows the number of sampled first admissions expected

to be eligible and the expected final first-admissions

sample sizes.

Resolution of Sampling Errors

A number of types of sampling errors can occur. In

most cases, the interviewer should have notified the

home office of the situation, continuing data collection

until a contact with the home office resulted in

instructions to proceed otherwise. These sampling errors

and their resolution were, for the most part, handled in

the CAPI software. Some errors that might occur, and

their resolution, are listed below. The first three types

could be resolved in the CAPI software.

• Person sampled as a first admission was a resident on

January 1, 1996.

Resolution: 

- First admission was not listed for currentresidents sample: Drop from the firstadmissions sample and code as a sampling

error; adjust current-residents sample weights.

- First admission was listed for both currentresidents and first-admissions samples: Drop

from the first-admissions sample and code as a

sampling error.

• Person sampled as a current resident was not a

resident on January 1, 1996, but was admitted later.

Resolution: 

- Current resident was not listed for firstadmissions sample: Drop from the currentresidents sample and code as a sampling error;

add to first-admissions list before firstadmissions sampling to ensure a chance of

selection.

- Current resident was listed for first-admissions

sample: Drop from the current-residents

sample.

• Person sampled as a first admission was admitted and

listed twice or more.

Resolution: 

- First admission was sampled on first admission:

Retain first admission in the sample.

- First admission was sampled on later admission:

Drop first admission from the sample.

• Eligible persons were omitted from listing.

Resolution: Call home office; adjust sampling

weights.

• Ineligible persons (e.g., residents of an assisted living

wing) were listed or sampled. 

Resolution: Call home office; clean list and

resample, if possible. May require CAPI intervention

from home office to allow resampling. If resampling

is not possible, CAPI software detects ineligible

sampled persons in the residence history

questionnaire and they are dropped from the sample

and coded as out of scope. 

These resolutions are not perfect. While they were

intended to preserve the rule of a single chance of

selection, they do not preserve the clear stratification of

the current-residents versus first-admissions samples. In

each case, the sampled person being dropped could

instead be retained if proper adjustments were made to

the sampling weights. It should be noted, however, that

this latter resolution would not preserve the stratification

of the two samples either. 
20

Figure 2. Final determination of eligibility for sampled nursing home

residents: 1996 MEPS Nursing Home Component.

Source: Agency for Health Care Policy and Research: 1996 Medical Expenditure Panel Survey Nursing Home Component.

Eligible

Eligible Eligible

Ineligible

Provisionally eligible 

or no community 

respondent

Provisionally

eligible

Provisionally

eligible

Ineligible

Ineligible

Ineligible Ineligible

Eligible

Ineligible Ineligible

Provisionally eligible 

or no community 

respondent
21

References

Agency for Health Care Policy and Research. NMES Public

Use File 8: Institutional Population Component, baseline

questionnaire. Rockville, MD; 1990.

American Hospital Association. American Hospital

Association guide to the health field. Chicago; 1993.

National Center for Health Statistics. Sampling frame for the

1995 National Nursing Home Survey (facility file)

[microdata tape documentation]. Hyattsville, MD; 1995.

Pancholi, M. Message to P. Broene in electronic mail

system, 1995 Oct 18; Pancholi, M. Unpublished memo to 

P. Broene, “The Updated Health Provider Inventory,” 

1995 July 17.
U.S. Department of Health and Human Services

Public Health Service

Agency for Health Care Policy and Research

2101 East Jefferson Street, Suite 501

Rockville, MD 20852

AHCPR Pub. No. 98-0042

September 1998