title: robust standard errors for mixed-effects models in lme4 package of R
body: <p>I am using the lme4 package for linear mixed effect modeling</p>
  <p>the mixed-effect model is below:</p>
  <pre><code>fm01 &lt;- lmer(sublat &lt;- goal + (1|userid))
  </code></pre>
  <p>the above command returns an S4 object called fm01</p>
  <p>this object includes fixed effects and their OLS standard errors (below)</p>
  <pre><code>Fixed effects:
  
              Estimate Std. Error t value
  (Intercept)   31.644      3.320   9.530
  goaltypeF1    -4.075      3.243  -1.257
  goaltypeF2    -9.187      5.609  -1.638
  goaltypeF3   -13.935      9.455  -1.474
  goaltypeF4   -20.219      8.196  -2.467
  goaltypeF5   -12.134      8.797  -1.379&quot;
  </code></pre>
  <p>however, i need to provide robust standard errors</p>
  <p>How can I do this with an S4 object such as returned by lme4?</p>