Lesson 5 · Other Designs and Approaches to Know · Step 2 of 7
Ecological studies
In an ecological study the unit of analysis is a group, such as a country, city or year, not a person. That suits exposures that belong to places, like climate, air quality or national policy, and it uses data that already exist: one study compared cancer mortality across 343 Latin American cities. The risk is the ecological fallacy. In 1930, US states with more foreign-born residents had higher literacy, although foreign-born individuals were slightly less literate. A group-level association can be stronger, weaker or reversed among individuals.
Also covered: unit of analysis · ecological fallacy · aggregate data · hypothesis generation
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Lesson 5 · 7 steps
Research Designs · lesson 5 of 5