title: drop1 function for lmer
body: <p>I constructed a mixed effect model with three fixed effects and one random effect. </p>
  
  <pre><code>mdl1 &lt;- lmer(yld.res ~ veg + rep + rip + (1|state),
         REML=FALSE,data=data2)
  </code></pre>
  
  <p>I want to get the most parsimonious model from the above model. To do this, I want to drop one independent variable at a time and see if it improved the fit of the model (by looking at the AICc value). But when I use <code>drop1</code>, it gives me the following error:</p>
  
  <pre><code>drop1(mdl1, test="F")
  
  Error in match.arg(test) : 'arg' should be one of “none”, “Chisq”, “user”
  </code></pre>
  
  <p>I am not really sure how to go about this and would really appreciate any help. </p>