Table A. Comparison of Selected Characteristics of the NCHS Hospital Discharge Survey, the NCHS Health Interview Survey, the American Hospital Association (AHA) National Hospital Panel Survey and the Health Care Financing Administration (HCFA) Medicare Statistical System (Hospital Portion).

Data System
Characteristic	NCHS National Hospital Discharge Survey	NCHS National Health Interview Survey	AHA National Hospital Panel Survey	HCFA Medicare Statistical System (Hospital Portion)
Universe	Short-stay1 non-Federal general and special U.S. hospitals excluding hospital units of other institutions	Civilian, noninstitutionalized U.S. population	Short-term,1 non-Federal, general and special U.S. hospitals excluding hospital units of other institutions and hospitals not registered with the AHA	Medicare beneficiaries discharged from short-stay1 hospitals participating in Medicare. (Military and Veterans Administration hospitals do not participate in Medicare).
Sample	Stratified probability sample of hospitals and a random or systematic sample of discharges within each hospital	Multistage probabilty sample of households	Probabilty sample of hospitals stratified on number of beds and census region	100 percent data for some information; for a 20 percent probability sample, diagnosis and surgical procedure are coded
Lowest level of aggregation	Individual discharge	Individual discharge	Hospital	Individual discharge
Response Rate	423 of 491 (86 percent) of eligible selected hospitals in 1977	96.2 percent in 1978	Averages about 70 percent each month	Not applicable, administrative records
Methods of Gathering Data	Information on each sample discharge is abstracted from medical record face sheet either by hospital staff and/or Census Bureau representatives	Household interviews conducted continuously through year	Hospitals in sample complete a survey form each month	Data derived from administrative records (Medicare admission notices and Medicare hospital bills)
Principal Data Items Collected	Patient characteristics: age, race, sex, marital status, and beginning in 1977, zip code of residence and expected source of payment Hospital Stay Information: Date of admission and discharge, discharge status. A maximum of 5 diagnoses and 3 surgeries are coded	Demographic data, acute and chronic conditions, limitation of activity, disability days, health care use (physicians, dentists, hospitals). In addition, data on special topics (such as health insurance coverage) may be collected for a year Hospital Stay Information: Dates of Hospitalization(s), name and address of hospital, reason (condition) for entering hospital, operations	Hospital characteristics: size, finances, number of employees Hospital use: number of admissions, patient days and outpatient visits	Hospital Stay Information: Dates of admission and discharge, discharge status, hospital charges and reimbursement, date of surgery. Principal diagnosis and surgical procedure coded for 20-percent sample Patient (beneficiary) and hospital characteristics from other files are linked to hospital stay on basis of beneficiary and hospital ID numbers in hospital bill

¹Average length of stay of less than 30 days.