# Population at Risk

# POPULATION AT RISK

The term "population at risk" defines the denominator for the calculation of rates of incidences and prevalence. It alludes to the number of persons potentially capable of experiencing the event or outcome of interest. The number or persons who actually experience the event make up the numerator of the rate. For rates to be valid and meaningful, the population at risk must be known accurately. However, many vital statistical rates are calculated on an annual basis, and for these rates the midyear population, or an approximation based on extrapolation from a recent set of census data, is often used for the population at risk. As rates incorporate an element of time, the denominator is often expressed in person-time rather than as the population at risk.

John M. Last

(see also: *Epidemiology; Rates; Rates: Adjusted* )

## Bibliography

Rothman, K. J., and Greenland, S., eds. (1998). *Modern Epidemiology,* 2nd edition. Philadelphia, PA: Lippincott-Raven.

#### More From encyclopedia.com

Risk , Risk
Risk is the potential for harm. Although the concept of risk—and some of the same analytic tools—are also used in finance and actuarial science,… Demography , Demography is the scientific study of the size, composition, and distribution of human populations, and their changes resulting from fertility, morta… Standardization , Standardization is a technique used in comparing indicators from two or more populations. The goal of the standardization procedure is to control for… Population Studies , Population studies is broadly defined as the scientific study of human populations. Major areas studied include broad population dynamics; fertility… Mortality , mortality, mortality rate The death-rate, usually standardized by age and sex, to facilitate comparisons between areas and social groups. It provides… you'll find our current interest rate very competitive. , rate1 / rāt/ • n. 1. a measure, quantity, or frequency, typically one measured against some other quantity or measure: the crime rate rose by 26 perc…

#### You Might Also Like

#### NEARBY TERMS

**Population at Risk**