It is based on a stratified probability sample of hospitals, with sampling probabilities proportional to the number of U.S. community hospitals in each stratum. NIS Release 6 is drawn from 22 States and contains information on all inpatient stays from over 1,000 hospitals, totaling about 7.1 million records in 1997. Inpatient stay records include clinical and resource use information typically available from discharge abstracts. Hospital and discharge weights are provided for producing national and State-level estimates. Access to the NIS is open to users who sign data use agreements.
Uses are limited to research and aggregate statistical reporting.
Documentation and tools files . The following is a brief description of these types of files. Core File A contains the most commonly used data elements and Core Files B and C contain less commonly used data elements. Documentation and Tools Files Documentation. See Getting Started for more information.