Epi formulas

Prevalence

(Number of cases existing at a specific time) / (Total population at risk) 

Incidence

(Number of New Cases) / (Population at Risk x Time Period) 

crude rates

number of events/ mid-year population x 100

crude birth rate

number of live births/ mid-year population x 100

general fertiliy rate

number of live births/ number of women of reproductive age X100

infant mortality rate

(Number of infant deaths under 1 year old / Number of live births) x 1,000

fetal death rate

(Number of fetal deaths / Number of live births + fetal deaths) x 1000

neonatal mortality rate

the number of deaths of infants under 28 days of age per 1,000 live births.

maternal mortality rate

(Number of maternal deaths / Number of live births) x 100,000

cause specific rate

(Number of deaths from a specific cause / Population at risk) * 100,000