Laura: I think you need to include an interaction of Year + newWater (i.e., Year:newWater) if you want trends across Year to be able to differ by newWater categories (the common regression modeling approach of allowing separate slopes and intercepts among different categorical groups in a common model). As you currently have your model parameterized, only the intercept terms are able to differ among newWater categories (of course, this assumes that you have newWater in as a design contrast among categorical factor levels).
Brian Brian S. Cade, PhD U. S. Geological Survey Fort Collins Science Center 2150 Centre Ave., Bldg. C Fort Collins, CO 80526-8818 email: [email protected] <[email protected]> tel: 970 226-9326 On Thu, Jul 3, 2014 at 2:17 PM, Lee, Laura <[email protected]> wrote: > Hello all! > > I am trying to model censored catch-per-unit-effort (CPUE) data. The data > are censored by trip limits that vary by year. I am using the 'gamlss' and > 'survival' packages. My model covariates are Year and newWater. I need to > get annual trends in CPUE by waterbody (newWater). After running the model > and computing the index, I find the trends are the same among all water > bodies--the magnitude is slightly different. I would not expect the trends > to be the same among the different areas. I would appreciate any > assistance. Code is below. > > cy <- with(data, ifelse(NUMBERS>=Limit, Limit, NUMBERS)) > ci <- with(data, ifelse(NUMBERS>=Limit, 0, 1)) > data <- data.frame(data, cy, ci) > rm(cy,ci) > gen.cens("LOGNO",type="right") > cfit <- gamlss(Surv(cy, ci) ~ YEAR + newWater, data=data, family=LOGNOrc) > data$y <- exp(fitted(cfit)) > out <- with(data, tapply(y, list(YEAR,newWater), mean)) > > Thanks again for your help, > > Laura > > _______________________________________________ > R-sig-ecology mailing list > [email protected] > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology > [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
