  Negative Binomial regression is a staple in Operations Management empirical
research. Most of its analytical aspects are considered either self-evident, or
minutiae that are better left to specialised textbooks. But what if the
evidence provided by trusted sources disagrees? In this note I set out to
verify results about the Negative Binomial regression specification presented
in widely-cited academic sources. I identify problems in how these sources
approach the gamma function and its derivatives, with repercussions on the
Fisher Information Matrix that may ultimately affect statistical testing. By
elevating computations that are rarely specified in full, I provide
recommendations to improve methodological evidence that is typically presented
without proof.
