Appendix B. The SAS code used to fit a Poisson regression to detailed and aggregate data.
| data wasps; |
| input PlHour visit capture; |
| logPH = log(PlHour); |
| /* aggregate data does not have a number of visits */ |
| if visit = . then do; |
| Xcapture = 1; |
| Xvisit = 1; |
| Y = capture; |
| offset = logPH; |
| output; |
| end; |
| else do; |
| /* detailed data includes a number of visits, generates 2 obs. */ |
| /* for visits |
| Xcapture = 0; |
| Xvisit = 1; |
| Y = visit; |
| offset = logPH; |
| output; |
| /* and for captures */ |
| Xcapture = 1; |
| Xvisit = 0; |
| Y = capture; |
| offset = log(visit); |
| output; |
| end; |
| cards; |
| 376.5 157 2 |
| 1416 . 6 |
| ; |
| proc print; |
| proc genmod data = wasps; |
| model y = Xcapture Xvisit /d = poisson link = log |
| offset = offset noint obstats lrci; |
| title 'Combined estimate of capture and visit rates'; |
| run; |