(This article was originally published at Statistical Modeling, Causal Inference, and Social Science, and syndicated at StatsBlogs.)
Greg Laughlin writes:
Someone asks, “How do you know [if a group-level finding shouldn't be used to describe individual level behavior]?” The best answer I had was “you can never tell without the individual-level data, you should always be suspicious of group-level findings applied to individuals.”
Am I missing anything? Are there any situations in which you can look at group-level qualities being ascribed to individuals and not have to fear the ecological fallacy?
My reply: I think that’s right. To put it another way, consider the larger model with separate coefficients for individual-level and group-level effects. If you want, you can make an assumption that they’re equal, but that’s an assumption that needs to be justified on substantive grounds. We discuss these issues a bit in this paper from 2001. (I just reread that paper. It’s pretty good!)
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