Simone Vincenzi <simone.vincenzi <at> nemo.unipr.it> writes: > > Dear R-list, > I have a statistical problem with the comparison of two short time-series of > density data in an ecological framework. I have to compare two short time > series (5 years, one value for each year) of species density data (it is the > density of fish in two different streams) to test if the two means of the > five densities are significantly different, so basically if the two mean > stream-specific fish densities are significantly different. > I don't think I can use a straight t-test due to the problem of > autocorrelation and I don't think I can use a repeated measure ANOVA as I > don't have any replicates. > Any help would be greatly appreciated.
try something like library(nlme) summary(lme(dens~stream+year,data=mystreamdata,random=~year|stream)) This should also give you an estimate if the slopes are different if you test against the simplified model summary(lme(dens~stream+year,data=mystreamdata,random=~1|stream)) Since you did not provide a short example data set, this is only approximatively right. Dieter ______________________________________________ [email protected] 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.
