I am interested in using Generalized Estimating Equations (GEE) to model longitudinal count data. I recorded animal count observations on the same sites on many days but the spacing of the observations was uneven. I was wondering if there is a way to specify this uneven structure when using an autoregressive correlation structure?
for example, when using lme from the nlme package to analyze linear mixed models it is possible to specify the correlation structure as:
correlation = corAR1(form = ~DAY | Subject)
That way the spacing of the observations for the autoregressive structure is adjusted based on DAY. Is there a way to do this in R in a GEE model using a package such as geepack, gee, or any others?