Covariates for dummies

[klf20]

I am attemting to work with a snapping turtle populaiton data set and was interested in working with the weight at initial capture as a covariate to predict capture probablity . I'm not quite sure I can do this because it would not be the same at each capture. Anyway, being a new user and despite reading the mark manual etc. I'm still not sure of where to begin. Is there anyone that would be willing to help me get started.

Thanks

Kelley F

[cooch]

I am attemting to work with a snapping turtle populaiton data set and was interested in working with the weight at initial capture as a covariate to predict capture probablity . I'm not quite sure I can do this because it would not be the same at each capture. Anyway, being a new user and despite reading the mark manual etc. I'm still not sure of where to begin. Is there anyone that would be willing to help me get started.

Well, I'm somewhat surprised you can't answer ths for yourself, if (as you say) you've read the manual - since this sort of thing is talked about at great length in many places. Specifically, read the chapter on individual covariates (Chapter 12). It covers just this sort of thing in considerable detail. If you have time-varying covariates that you don't always measure (e.g., you don't simply want to condition on size at capture, but rathermake time-specific capture a function of size at/over a particular sampling interval), you can apply one of several approaches - the most tractable (for the moment) is to treat the problem as a multi-state problem - see section 12.5 in the individual covariates chapter.