title: Extract random effect variances from lme4 mer model object
body: <p>I have a mer object that has fixed and random effects.  How do I extract the variance estimates for the random effects?  Here is a simplified version of my question.</p>
  
  <pre><code>study &lt;- lmer(Reaction ~ Days + (1|Subject), data = sleepstudy)
  study
  </code></pre>
  
  <p>This gives a long output - not too long in this case.  Anyway, how do I explicitly select the</p>
  
  <pre><code>Random effects:
  Groups   Name        Variance Std.Dev.
  Subject  (Intercept) 1378.18  37.124  
  Residual              960.46  30.991  
  </code></pre>
  
  <p>part of the output?  I want the values themselves.</p>
  
  <p>I have taken long looks at</p>
  
  <pre><code>str(study)
  </code></pre>
  
  <p>and there's nothing there!  Also checked any extractor functions in the lme4 package to no avail.  Please help!</p>