Prevalence is a:

Tools of measurement in epidemics: - Rate = x 1000/ 10000/ 100000 ; a is pa of b - Ratio = a/b ; a is not a pa of b - Propoion = x 100 = % ; a is pa of b Prevalence = No. of all current cases of a disease at a time /Estimated total population at that time X 100 Hence, Prevalence is a propoion (Prevalence is NOT a Ratio): Numerator is a pa of denominator & is always expressed in percentage. Incidence is rate.