title: 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)
body: <p>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;</p>
  
  <pre><code>&gt; Attach(Data)
  &gt; library(car)
  &gt; options(contrasts = c("contr.sum", "contr.poly"))
  &gt; mod &lt;- aov(Response ~ A*B*C + Error(Block/A/B/C))
  &gt; Anova(mod, type='III')
  Error in vcov.default(mod) :
       there is no vcov() method for models of class aovlist, listof
  </code></pre>
  
  <p>I don't understand why I keep getting this error message, or what to do about it. </p>
  
  <p>Any help trying to get around this error message would be greatly appreciated. Thanks in advance! </p>