Hello all, I am trying to conduct a GLM with poisson distribution in JMP. I want to use 2 categorical variables as predictors for count data. However, I notice that in the "Parameter Estimates" report table, 1 fewer than the number of levels I have for each category shows up with an estimate. For example, I am looking at 3 habitat types, types A, B, and C. Parameter estimates only show up for Types A and B, not C. The same happens for my 4 times of day variables, only 3 show up in parameter estimates. I'm not sure I understand why. Can anyone help me with this?