search for: carabid

Dear R-users, is there a chance to do an nested ANCOVA in R? I've read the archive mails but it doesn't work. We have the following situation: We are interested in differences in carabid biomass at different aged woodlands. Thus, we have a nested design with 2 fixed groups (0=recent, 1=ancient) and 10 woodlands (each with 8 replications/traps) per fixed group. Woodland is therfore nested within the fixed variable. In an additional step we want to calculate these procedure with a c...

Hello, I have used R in the past to conduct multiple comparisons on standard linear models, but am a bit confused as to how to go about doing it with a mixed effects model. I am conducting a bioindication study using carabid beetles in which I have four treatment types (forest harvest types with varying levels of canopy structure retention), and am using canopy closure percent as a covariate in my ANCOVA model. The response variable is species diversity (richness). I am wanting to use a mixed effects model because the...

...is I did about 18 months ago (the reviewers of the paper want something adding to it). I'm using R1.5.0, but I couldn't see anything in the list of changes between this and 1.5.1 to suggest it would act any differently. The data is observational, on the changes in the population status of carabid beetles, and various attributes of the species which may or may not explain what's happening. The response is ordinal - there are several categories, from (roughly) "Gone Extinct" to "Suddenly all over the damn place", and because the beetles haven't read Cochran and Co...