What is denominator?
denominator is 1). The lower portion of a fraction used to calculate a rate or ratio. In a rate, the denominator is usually the population at risk. 2). For a performance measure, the sample of cases that will be observed (e.g. the number of patients discharged alive with a confirmed diagnosis of acute myocardial infarction, excluding patients with bleeding or other specified conditions).
source: A GLOSSARY OF TERMS FOR COMMUNITY HEALTH CARE AND SERVICES FOR OLDER PERSONS. World Health Organization, 2004.