Error in vcov.default(mod) : there is no vcov() method for models of class list (changing from type I to type III Sum of Squares)

问题

I am trying to get an ANOVA table for my split-split plot design where it will use type III Sum sq instead of type I. This is what I have done so far;

> Attach(Data)
> library(car)
> options(contrasts = c("contr.sum", "contr.poly"))
> mod <- aov(Response ~ A*B*C + Error(Block/A/B/C))
> Anova(mod, type='III')
Error in vcov.default(mod) :
     there is no vcov() method for models of class aovlist, listof

I don't understand why I keep getting this error message, or what to do about it.

Any help trying to get around this error message would be greatly appreciated. Thanks in advance!

来源：https://stackoverflow.com/questions/47440031/error-in-vcov-defaultmod-there-is-no-vcov-method-for-models-of-class-list