Lesson 2: Measurement (1) Case Definition and Measures

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Introduction

Epidemiologists ask “Who gets the disease? In what frequency? Is the frequency changing over time? How does the frequency in one population compare to the frequency in another population?” Answering such questions first requires a case definition.  Second, we then need measures to estimate disease frequency.  Third, we may want to compare measures in different populations..

When you have completed this lesson, you will be able to do the following:

  1. Define a case for epidemiologic purposes;
  2. Select and use measures of disease frequency;
  3. Calculate prevalence and incidence from surveillance data;
  4. Define point prevalence, period prevalence, cumulative incidence, and incidence density

Reference

 Coggon, D., G. Rose and DJP Barker. "Quantifying disease in populations" in Epidemiology for the Uniniated. Fourth Edition.  BMJ Collection.  https://resources.bmj.com/bmj/readers/readers/epidemiology-for-the-uninitiated/2-quantifying-disease-in-populations  20 Jan 2011.