sickboyedd <sickboyedd <at> gmail.com> writes: > > > Hello all, > > I am hoping to use survival analysis to examine whether parasite attack > increases nest death in a species of social wasp. I therefore have data for > > 1. Whether the nest "died" in the 6 week census period ("Status", where > 1=died, 0=survived) > 2. The day number of death/last recorded day it was observed alive. > 3. Whether the nest was attacked by the parasite (0/1 as with 1.) > 4. The day number of attack/ last recorded day the nest was observed without > a parasite. > > i.e. example dataset: > > status death para paraday > 0 42 0 42 > 1 32 0 42 > 1 25 1 13 > 0 42 1 25 ... > > I've looked over r-help, as well as in Crawley etc., but I have yet to find > a solution. Can anyone point me in the right direction or literature? >
You might want to send this to r-sig-ecology if you need further discussion. In the meantime, the very simplest thing (conditioning on whether the nest was attacked or not) would be library(survival) c1 = coxph(Surv(death,status)~para,data=mydata) (you should definitely read up a bit on survival analysis, Cox proportional hazards, etc.. I think there's a chapter in the book by Scheiner and Gurevitch, geared towards ecologists). Dealing with parasite attack in a more fine-grained way (i.e. assessing mortality before and after parasitism) would be a little trickier, but I wouldn't worry about it until after you've understood the first stage of the analysis. Ben Bolker ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.