A way of seeing
Almost everything you believe about your health began as a pattern in a population.
Does coffee harm you? Does a drug work? Is the air safe? Every answer we trust came from someone comparing groups of people and asking whether the difference was real — or a trick of the data. That discipline is epidemiology, and this is where you learn to see it.
Proof · 60 seconds
Does coffee cause heart attacks?
Keep Playing
More Ways the Numbers Fool Us
You just met a confounder. Each of these is a short, playable story about how easy it is to reach the wrong conclusion — and how epidemiologists catch it.
For Students
Learn epidemiology by doing. Manipulate populations, observe associations, introduce bias, and see what happens. No formulas required to start — just curiosity.
For Instructors
Replace a lecture with a live demonstration. Use preset scenarios to show confounding, Simpson's paradox, or selection bias in real time. Assign interactive exercises tied to each chapter.
For Everyone
Epidemiology shapes policy, headlines, and daily life. Understand how we know what causes disease — and why it matters who we study and how we study them.
The Framework
Seven Steps for an Epidemiology of Consequence
The book organizes epidemiologic thinking around seven foundational steps. Each builds on the last. Together, they constitute a complete framework for studies that matter.
Interactive Companion
Learn by Doing
Each tool maps directly to the book. Use them in class, assign them as exercises, or explore on your own. The print edition includes QR codes linking to each module.
Causal Thinking Lab
Build a data-generating process. Add confounding, measurement error, and selection bias. See how they distort causal estimates. Five preset scenarios for classroom use.
Population & Prevalence
Adjust disease and exposure in a population of Farrlandians. Watch prevalence, risk ratios, and risk differences update in real time.
Component Cause Model
Toggle causes for individual Farrlandians. Disease occurs when a sufficient cause is complete. Different people, different pathways, same disease.
Study Design Builder
Walk through all seven steps to design your own epidemiologic study of consequence.
Explore Farrlandia
1,000 Farrlandians with full profiles. Hover to meet them. Filter, stratify, and compute associations from the living dataset.
Screening Simulator
Adjust a test’s accuracy and how common a disease is. Watch how often a positive result is actually a false alarm — a result that surprises almost everyone.
New in the Second Edition
Consequence Boxes
Each chapter connects a methodological choice to a question of social responsibility.
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?
Fresh From the Library
Latest Articles & Media
Long-form pieces and short animations that extend the book. New work lands here first.
Launching Fall 2028
The Farrlandia Challenge
An inter-school competition for public health students. Investigate an outbreak in Farrlandia. Identify causes. Propose interventions. Compete against teams from schools across the country.
4 Rounds, 4 Weeks
Each round follows the seven-step framework: define, investigate, challenge, intervene.
Real Tools
Teams use the platform's interactive modules to analyze the Farrlandia dataset.
Free to Enter
Open to any team of 3–5 students enrolled in a public health program.
Consequentialist Scoring
Judged on rigor, population impact, communication, and creativity.
On the Calendar
What’s Coming
The Authors
Keyes, Abba-Aji, and Galea
The Book · Second Edition · Coming 2028
Epidemiology Matters
Everything you just played is drawn from the textbook by Keyes, Abba-Aji, and Galea, published by Oxford University Press. The print edition carries QR codes that open each interactive module. Be the first to know when it launches.
Stay Updated
Get notified when new tools launch, when the Farrlandia Challenge opens, and when the second edition is available.
We will only email you about the book and the platform. No spam.