Following is true about attack rate EXCEPT
An attack rate is an incidence rate (usually expressed as a percent), used only when the population is exposed to risk for a limited period of time such as during an epidemic. It reflects the extent of an epidemic. Attack rate = Number of new cases of a specified disease during a specified interval / Total population at risk during the same interval x 100 Ref : Park 23rd edition Pgno : 131
It is a type of prevalence rate
Expressed as percentage
Reflects extent of epidemic
Total population at risk is taken as denominator
Epidemiology