Study Guide: Measuring Things in Epidemiology

Measures Used in Epidemiology. A two-by-two table can be used to quantify exposure and disease. Row headings: E+ indicates the number of people who are exposed, E- indicates the number of people who are unexposed. Column headings: D+ indicate the number of people with disease and D- the number of people without disease. E+ with D+ is A in top left cell of the table; for example, where A is a number that is both exposed and with disease. E- with D+ is C in bottom left cell. E+ with D- is B in top right cell. E- with D- is notated as D in bottom right cell. These numbers as represented by A, B, C, and D, which are then used to calculate incidence and prevalence. Incidence is the risk of disease and is calculated by dividing the number of cases by the number of people at risk at a point in time multiplied by 100, 1,000, or 100,000. The number of people at risk could be the average population or person-time (among other options). Prevalence is the burden of disease and is calculated by dividing the number of people with disease by the total population (the entire population of interest). Prevalence can be shown as a percentage. On left, Graph with declining step on x- and y-axis. Kaplan-Meier is one way to calculate cumulative incidence and cumulative survival.

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Epidemiology Copyright © 2023 by Charlotte Baker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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