How do I interpret the estimates for the fixed part parameters in a Poisson model?
The interpretation of the output depends on how you have set your model up, in particular on what you have used as the offsets. If you have set your model up so that the response variable is for example the number of deaths and the offset variable is the log of the number at risk, then the estimates that you see in the Equations window for the coefficients (in the fixed part of the model) will be the effects on the log rate, so that you need to take the exponential of each coefficient to get the effect on the rate. If on the other hand you do as in the example in Chapter 12 of the User’s Guide and use as the offset variable the log of the expected number of deaths, then the estimates that you see in the Equations window for the coefficients of the fixed part of the model will be the effects on the log ratio of observed to expected deaths, and the exponentials of the coefficients will be the effects on the ratio of observed to expected deaths. (Note that it is more usual to use the log
