The Importance of Including an Exposure Variable in Count Models

by Jeff Meyer

When our research question is focused on the frequency of occurrence of an event, we will typically use a count model to analyze the results. There are numerous count models. A few examples are: Poisson, negative binomial, zero-inflated Poisson and truncated negative binomial.

There are specific requirements as to which count model to use. The models are not interchangeable. But regardless of the model we use, there is a very important prerequisite that they all share.

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