Article

Tutorial on Using Regression Models with Count Outcomes using R

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Abstract

Education researchers often study count variables, such as times a student reached a goal, discipline referrals, and absences. Most researchers that study these variables use typical regression methods (i.e., ordinary least-squares) either with or without transforming the count variables. In either case, using typical regression for count data can produce parameter estimates that are biased, thus diminishing any inferences made from such data. As count-variable regression models are seldom taught in training programs, we present a tutorial to help educational researchers use such methods in their own research. We demonstrate analyzing and interpreting count data using Poisson, negative binomial, zero-inflated Poisson, and zero-inflated negative binomial regression models. The count regression methods are introduced through an example using the number of times students skipped class. The data for this example are freely available and the R syntax used run the example analyses are included in the Appendix. Accessed 16,559 times on https://pareonline.net from February 02, 2016 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right.

Keywords: Educational Research, Research Methodology, Statistical Analysis

How to Cite:

Beaujean, A. A. & Grant, M. B., (2016) “Tutorial on Using Regression Models with Count Outcomes using R”, Practical Assessment, Research, and Evaluation 21(1): 2. doi: https://doi.org/10.7275/pj8c-h254