Second Edition — Coming 2028

Epidemiology Matters

An introduction to methodological foundations. Seven steps toward an epidemiology of consequence.

Katherine M. Keyes · Mohammed Abba-Aji · Sandro Galea

100 Farrlandians — 20 with disease

Explore PrevalenceBuild a Study
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Disease in a Population

Adjust the sliders to see how prevalence and measures of association change.

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50
● Diseased● Exposed (healthy)● Unexposed (healthy)
Interactive — Chapter 7

Causation: The Sufficient-Component Cause Model

No single factor causes disease alone. Disease occurs when all the component causes in a sufficient cause are present in the same individual. Click on a Farrlandian to add or remove component causes, and watch what happens when a sufficient cause is complete.

Each person has different combinations of causes. A sufficient cause is like a complete recipe — every ingredient must be present.

Obesity
No preventive care
Family history
Smoking
Sedentary lifestyle

Click on a person to toggle their component causes. Disease occurs when all causes in at least one sufficient cause are present.

The Framework

Seven Steps for an Epidemiology of Consequence

Each decision shapes what we can learn and what we can do with what we learn.

Design Your Study

Walk through the seven steps to design an epidemiologic study of consequence.

Your Study Design

A summary of your epidemiologic study of consequence.

New in the Second Edition

Consequence Boxes

Each chapter connects methodological choices to questions of social responsibility.

◆ Consequence Box · Chapter 3

How we define a health indicator determines who counts as a case. Who counts determines what risk factors we find. What we find determines what gets funded.

Consider depression. A clinical interview identifies fewer cases than a screening tool. Those missed are disproportionately people without access to clinical settings. The measurement choice is not neutral.

When you choose a measure, ask: whose health does this make visible, and whose does it obscure?