* Sample code for fitting logistic-exposure models (Shaffer 2003) to 
* interval nest-visit data. 
*
*  Variables are as follows:
*
*  Ifate = 0 if nest fails the interval, and 1 if it survives.
*  Trials = 1 in all cases.
*  Avgage = age (d) of the nest at interval midpoint.
*  PctGr = proportion of grassland cover. 
*  t = interval length (d)
* 
*  Macros for generating AIC analyses and model-averaged parameter
*  estimates are available from
*  http://www.npwrc.usgs.gov/resource/tools/nestsurv/nestsurv.htm 
*;

Proc Genmod Data=Mall;
  Fwdlink link = log((_mean_**(1/t))/(1-_mean_**(1/t)));
  Invlink ilink = (exp(_xbeta_)/(1+exp(_xbeta_)))**t;
  Model Ifate/Trials = Avgage PpnGr / Dist=bin;
  Ods output modelfit=modelfit;
  Ods output modelinfo=modelinfo;
  Ods output ParameterEstimates=ParameterEstimates;
  Title 'b0 + b1*avgage + b2*pctgr4';
Run;