Correlation and causation

What’s the difference?

I’ve got a joke about silly correlations. There was this American who was afraid of a heart attack and he found out that the Japanese ate very little fat and almost didn’t drink wine but they had much less heart attacks than the Americans. But on the other hand he also found out that the French eat as much fat as the Americans and they drink much more wine but they also have less heart attacks. So he concluded that what kills you is speaking English. (Hans Rosling, 2011, Open University, www.tinyurl.com/bsamfuz)

Geographers use statistical methods as tools to help them understand and make sense of their data, including data collected during fieldwork. Like any tool, they need to be used correctly. If they are used in the wrong way, statistics can generate inaccurate, misleading and even incorrect conclusions based on the research data.

This Practical Geography focuses on one of the most commonly used statistical tools in geography: correlation. It also takes a closer look at the idea of causation. What do these two terms mean? When and how should they be used? Read on for some explanation and demystification of these important concepts.