XI. Sources of ‘chronology bias’ in cohort statistics

Abstract

In the previous paper of this series, 13 a cohort was defined as a group of people who are followed forward in time to observe the effects of a maneuver to which they have been exposed. The results are usually expressed statistically as a ratio, or rate, in which the denominator of the cohort contains the number of people exposed to the maneuver, and the numerator contains the number of those people who later developed a particular target event.