# EPID 301 Lecture Notes - Lecture 4: Maternal Death, Poisson Distribution, Standardized Mortality Ratio

## Document Summary

Expressed as a: ratio, relationship of one quantity to another quantity. Cumulative incidence, incidence density, incidence odds: cumulative incidence. Known as incidence proportion or the cumulative incidence rate with no units. Ci = (number of new occurrences during a specific time period)/(population at. Risk) x 10^n: ci = cumulative incidence, 10^n is population base, reason of base 10 is to avoid reporting decimal fractions. Cumulative incidence is useful in cohort studies because it measures average risk (probability) of developing occurrence during follow up period. Deaths due to competing risks and losses to follow up will affect measure of risk. Special measure of cumulative incidence applied to narrowly but well- defined population being observed over limited time period. Study population of 4,500 men 65- 74 years of age in cedar iowa to determine incidence of prostate cancer. Seven percent already had prostate cancer. Five years of follow up 156 men had prostate cancer. Number of new occurences = 156.