When the response is a count (a positive integer), we can use a count regression

model to explain this response in terms of the given predictors. Sometimes, the total

count is bounded, in which case a binomial response regression should probably be

used. In other cases, the counts might be sufficiently large that a normal approxima-

tion is justified so that a normal linear model may be used. We shall consider two

distributions for counts. The Poisson and, less commonly, the negative binomial.