G'day, I'm fitting a simple one-way nested anova and would like to obtain standard errors or confidence limits. I'm using se.contrast to try to get se for the contrast between the two levels of the main effect, but I get an error message (see below). What is going on? Don > shp<-factor(rep(c("reserve","strip"),each=96)) > site<-factor(rep(c("1g","1p", "1t","2g","2p","2t","3g","3p","3t","4g","4p","4t"),each=16)) > pit<-factor(rep(1:16,12)) > reptsp<-c(4,5,6,4,6,6,6,7,3,5,2,2,4,8,5,4,2,4,2,2,4,5,2,4,4,4,3,2,3,2,5,3,5,3,4,4,4,3,4,3,4,4,4,3,4,3,6,3,3,5,4,6,4,4,2,4,2,6,5,5,5,7,4,4,5,1,4,5,6,5,5,2,6,3,5,6,4,5,4,8,2,4,2,4,2,4,3,3,4,4,3,2,1,3,4,4,2,2,3,2,4,1,2,2,3,4,5,5,3,5,5,4,1,1,2,1,3,1,4,1,6,1,2,3,2,2,2,1,1,2,2,6,5,3,2,3,5,3,2,3,2,1,3,2,4,4,3,3,3,1,2,4,3,4,5,6,5,2,3,2,2,5,5,5,2,2,5,2,4,4,3,2,2,3,2,2,2,2,5,4,3,3,5,2,5,4,3,2,2,2,1,2) > ddata<-data.frame(shp,pit,site,reptsp) > #Fit a Standard Nested Anova Model > repmod1<-aov(reptsp~shp/site/pit+ Error(shp/site/pit)) > summary(repmod1) Error: shp Df Sum Sq Mean Sq shp 1 53.13 53.13 Error: shp:site Df Sum Sq Mean Sq shp:site 10 61.885 6.189 Error: shp:site:pit Df Sum Sq Mean Sq shp:site:pit 180 318.56 1.77 > se.contrast(repmod1, list(shp=="strip", shp=="reserve"),data=ddata) Error in rep.int(n.object - 1, nrow(c.qr) - length(e.assign)) : invalid number of copies in "rep"