The interpretation of a Poisson model differs according to the goals of the study. A researcher can be interested in the expected counts or in the distribution of counts. When the analysis of the expected value is the aim of the study, several measures namely the partial effects, the factor change and/or the percentage change can be computed to assess the change of the expected value for a change in an independent variable (i.e. a covariate) keeping other variables constant. If the interest is in the distribution of counts or just the probability of a specific count, the probability of a count for a given level of the independent variables can be computed [17]