multiple sites

[Niels Leuthold]

I have a study where I have a relatively large number of small sites. The sites are too small to analyze individually but I was going to try to group the sites for a closed population analysis. I saw this mentioned in the Gentle Introduction, but am unsure if I am setting this up correctly. I looked around the book and searched the forums and wasn't able to find details (though I may not have the right keywords).

I set this up by using a grouping variable for each site. Then using PIMs I setup the capture and recapture probs to be equal for all sites. I have 3 samples so p(1,2,3) and c(4,5) for each site. Then using the design matrix I am able to form models with covariates. This then allows me to get estimates of the population at each site, while grouping data to estimate captures probs. Am I approaching this correctly or is there an alternative way to combine the sites?