Your model is fully saturated. It specifies terms that use up all degrees of freedom. There are no degrees of freedom left over for a Residual term and therefore there is no denominator for the tests.
When you drop one term, then those degrees of freedom are left over, that is they form the Residual, and are used as the denominator for the tests. The usual practice is to suppress the high-order interactions, in your example by model <- aov(GR ~ SR*HS*Pop*Popsize*Year - SR:HS:Pop:Popsize:Year) Please use spaces around the arrow, tilde, and + and - signs for legibility. Rich ______________________________________________ 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.
