comp.soft-sys.sas - The SAS statistics package.
Hello all. I have a question regarding the use of an offset statement. Here the scenario: subjects were interviewed two times, however, the number of days that passed between the two interviews varied (e.g., 500 to 1000 days). The outcome of interest was violence (yes or no). However, those with 1000 days between interviews would have more opportunities to be violent than those with fewer days between interviews. In this example, is it more correct to use an offset statement (i.e., the log of the number of days) as opposed to including a covariate that measured the number of days between the interviews (this would be in a GENMOD model with a binomial distribution). My original intent was to use the offset statement; however, I wasn sure if that was orecorrect than including a covariate in the model (and I couldn find any literature that was specific to this question). Thank you for any input that you can provide regarding this! Richard
Dear Friend, I am running Poisson Regression with exposure variables. In the reference and manual, when I set offset variable, the estimation is known to be 1. Could you explain me why it is 1? Minsup Song
I use "Proc genmod" to fit "negative binomial" regression. But there is no backward, forward, and stepwise in proc genmod to help me select the important varibles(proc reg has variable selection function). I have about 30 variables. Is there any method to select variables in genmod automatically. Thanks.