The basic unit of observation is the discharge abstract or the record of an inpatient’s stay in a psychiatrici or general hospital. The discharge abstract is completed at separation (discharge or death). Records are grouped into fiscal years based on the inpatient’s date of separation from the hospital. If an individual was hospitalized more than once in the same fiscal year, a separate record for each stay was submitted. Hence the basic units of observation are events, not unique patients. If an inpatient was admitted prior to the beginning of a fiscal year, the days stayed prior to the year of separation are included in the total days stayed for that event.

February 7, 2017