National Hospital Ambulatory Medical Care Survey, 2002 (ICPSR 4405)

Published: Feb 17, 2006

Principal Investigator(s):
United States Department of Health and Human Services. National Center for Health Statistics


Version V1

The National Hospital Ambulatory Medical Care Survey (NHAMCS) provides data from samples of patient records selected from emergency departments (EDs) and outpatient departments (OPDs) of a national sample of hospitals. The resulting national estimates describe the use of hospital ambulatory medical care services in the United States. For the 2002 survey, data were collected from 224 OPDs and 376 EDs. Among the variables included are age, race, and sex of the patient, reason for the visit, physician's diagnoses, cause of injury (EDs only), surgical procedures (OPDs only), medication therapy, and expected source of payment. For 2002, a number of updates and revisions have been made to the drug characteristics data. The variables CSTRATM and CPSUM have been added to assist in the computation of variances.

United States Department of Health and Human Services. National Center for Health Statistics. National Hospital Ambulatory Medical Care Survey, 2002. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2006-02-17.

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In preparing the data files for this collection, the National Center for Health Statistics (NCHS) has removed direct identifiers and characteristics that might lead to identification of data subjects. As an additional precaution NCHS requires, under Section 308(d) of the Public Health Service Act (42 U.S.C. 242m), that data collected by NCHS not be used for any purpose other than statistical analysis and reporting. NCHS further requires that analysts not use the data to learn the identity of any persons or establishments and that the director of NCHS be notified if any identities are inadvertently discovered. ICPSR member institutions and other users ordering data from ICPSR are expected to adhere to these restrictions.


2002-01-01 -- 2002-12-27

(1) Per agreement with NCHS, ICPSR distributes the data files and text of the technical documentation for this collection as prepared by NCHS. (2) Detailed information regarding the use of weight variables and variance estimation is located in the User Guide.

The NHAMCS used a four-stage probability design with samples of primary sampling units (PSUs), hospitals within PSUs, clinics within hospitals, and patient visits within clinics.

Visits to the emergency and outpatient departments of noninstitutional general and short-stay hospitals within the 50 states and the District of Columbia, which had an average length of stay of less than 30 days, or to hospitals whose specialty was general (medical or surgical) or children's general. Excluded were federal hospitals, hospital units within institutions, and hospitals with less than six beds staffed for patient use.

Patient visit records from hospital emergency departments and outpatient departments.

administrative records data



Users should use the variable PATWT when performing analyses.


  • The public-use data files in this collection are available for access by the general public. Access does not require affiliation with an ICPSR member institution.

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This study is maintained and distributed by the National Archive of Computerized Data on Aging (NACDA), the aging program within ICPSR. NACDA is sponsored by the National Institute on Aging (NIA) at the National Institutes of Heath (NIH).