[R] Ancova doesn't return test statistics
Johan A. Stenberg
johan.stenberg at emg.umu.se
Thu Nov 15 16:36:13 CET 2007
Dear all,
I'm quite sure that this is a stupid question, but I'll ask anyway.
I want to perform an ANCOVA with two continuous factors and three
categorical factors.
Plant population growth rate (GR) = dependent variable
Seed reduction due to herbivory (SR) = continuous explanatory variable
Herbivore species (HS, 2 levels) = categorical explanatory variable
Population (Pop, 24 levels) = categorical explanatory variable
Population size (Popsize) = continuous explanatory variable
Year (Year, 16 levels) = categorical explanatory variable
My model is technically simple:
model<-aov(GR~SR*HS*Pop*Popsize*Year)
However, R is not returning any F and P values – only Df, Sum Sq and
Mean Sq. I have to remove either Year or Pop in order to get the test
statistics. Why is this?
Thank you in advance!
Johan A. Stenberg, Umea University, Sweden
More information about the R-help
mailing list