Proportion

type of ratio in which numerator is part of denominator. = A/(A+B) x 100

Ratio

value obtained by dividing one quantity by another. consists of numerator and denominator, but does not necessarily have relationship

Rate

numerator consists of the frequency of disease over specified period of time, denominator is unit size of population at specific point in time

Prevalence

number of existing cases of disease in a population at designated time

Incidence

rate of development of a disease in a group over a certain time period