Biostatistics For Dummies

Chapter 15

Analyzing Incidence and Prevalence Rates in Epidemiologic Data

In This Chapter

Determining and expressing how prevalent a condition is

Calculating incidence rates, rate ratios, and their standard errors

Comparing incidence rates between two populations

Estimating sample size needed to compare incidence rates

Epidemiology studies the patterns, causes, and effects of health and diseases in defined populations (sometimes very large populations, like entire cities or countries, or even the whole world). This chapter describes two concepts, prevalence and incidence, that are central to epidemiology and are frequently encountered in other areas of biological research as well. I describe how to calculate incidence rates and prevalence proportions; then, concentrating on the analysis of incidence (because prevalence can be analyzed using methods described elsewhere in this book), I describe how to calculate confidence intervals around incidence rates and rate ratios, and how to compare incidence rates between two populations.

Understanding Incidence and Prevalence

Incidence ...