Quantitative Methods 2017

Incidence and prevalence

Individuals

T1

T2

Time

Point Prevalence:- total number of existing cases at a given time point

Period Prevalence:- total number of cases over a given time period

Prevalence Rate = Point Prevalence / #at risk at time point

Incidence:- total number of new cases over a particular time period

Incidence Rate = Incidence / #at risk during the period

FMB

If incidence and duration are constant:- Prevalence = incidence X duration