[R] Ancova doesn't return test statistics

[Richard M. Heiberger]

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