It is based on a stratified probabilty sample of hospitals, with sampling probabilities proportional to the number of U.S. community hospitals in each stratum. This release is drawn from 19 states and contains information on all inpatient stays from over 900 hospitals, totaling about 6.7 million records in 1995. Inpatient stay records include clinical and resource use information typically available from discharge abstracts. Hospital and discharge weights are provided for producing national estimates. Access to the NIS is open to all researchers who sign data use agreements.
Uses are limited to research and aggregate statistical reporting.
Because of its size this database supports analyses of rare and common conditions and procedures. The data on the CD set require a statistical software package such as SAS or SPSS to use for analytic purposes.