Dear SAS Communities, I have a problem writing the estimate for my interaction term for Poisson model. Here's a simple summary of my data: Outcome: Number of CT scans per person year Predictors: 1) Exposure categories: A, B, C 2) Time (re-centered): 1, 2, 3, .... 60 When I test for interactions between exposure and time, they are significant (p < 0.001) proc genmod data=mydata; class exposure (ref='C') / param=ref; model countCT = exposure time exposure*time / dist=poisson link=log offset=logpersonyear; run; My problem is writing the estimates because I need to report RR in my tables. With the time interaction term, I need to report my RR at different time 1, 2, ...60. I read from other posts, I need to have all 3 predictors in my estimate statement.... proc genmod data=mydata; class exposure (ref='C') / param=ref; model countCT = exposure time exposure*time / dist=poisson link=log offset=logpersonyear; estimate 'A vs C at time 1' exposure 1 0 time [?] exposure*time [?] estimate 'B vs C at time 1' exposure 0 1 time [?] exposure*time [?] [all other time in between....] estimate 'A vs C at time 60' exposure 1 0 time [?] exposure*time [?] estimate 'B vs C at time 60' exposure 0 1 time [?] exposure*time [?] run; I'm not sure how to fill up the [?] in the estimate statement. How do we calculate [exposure*time]? Your help if very much appreciated. Thank you.
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