What is an ecological study?

Ecological studies, sometimes called correlational studies, are observational studies that rely on population/group-level data rather than individual-level data. The units of comparison in these types of studies are often countries, family units, or neighborhoods.

When is it useful to conduct an ecological study?

Ecological studies are useful for determining correlations. This type of study only allows you to suggest that an association may be present. However, you would need to conduct more rigorous studies to be sure. Ecological studies are also good for generating hypotheses.

Ecological study example: Average wine sales data in high-income countries and the rate of throat cancer in each country.

Ecological studies are inexpensive and easy to conduct because the population-level data most often already exists. However, you may commit an ecological fallacy if you ascribe observed group-level associations to the individual. In our example, if you find that high-income countries have increased sales of wine and high rates of throat cancer, you commit an ecological fallacy if you conclude that an individual who frequently buys wine will also have an increased chance of getting throat cancer. This is an issue because ecological studies are not based on individual-level data.

Limitations

It is important to note that ecological studies do not adjust for individual-level confounders.

Ecological studies have several limitations, including, misclassification of data, missing data, and errors in the data collection or measurement method. Ecological studies only suggest associations, and as a result, you are not able to determine relative risks or odds.

I hope this post is helpful to readers. I started MyStudentHq as a way to learn and write about what I learn. My foray into epidemiologic study designs on this site is related to my commitment to learning and writing boldly.


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