Hello,
I am having difficulty with my individual covariate for my Brownie model.
The data set I am working with is a fishery based dead-recovery tagging study spanning 18 years, with both adult and juvenile tagged fish. The juveniles become adults after 1 year. The Brownie model I am building in RMark has an age variable and I am looking to add an individual covariate. This individual covariate is an efficiency rate of detection of fish recoveries that applies only to recovered fish, and I will be looking to make my recovery rate a function of this efficiency rate covariate. Currently, this efficiency rate is not time-varying.
However, because this covariate only applies to recovered fish (which is a small portion of the data set), most of my individuals have NA in the cov column, which RMark does not like.
How would I go about applying this covariate to my recovery rate parameters? I would like to avoid the multistrata method, as I have 11 different efficiency rates.
Would I be fine with the standardized covariates method, and just changing all those individuals with NA's to 0?
I have read Catchpole et al., 2008 and as far as I can tell (which admittedly may not be very far) they only deal with survival based parameters for the missing covariates.
Thank you very much for any advice.