title: anova.merMod recalculates models using REML = FALSE, where to find the reference?
body: <p>I have been using the <code>anova.merMod</code> function from <code>lme4</code> package to obtain p-values for fixed effects through likelihood ratio tests for a scientific publication (most reviewers still demand p-values in my field). I noticed that the <code>anova.merMod</code> function recalculates the <code>lmer</code> functions using <code>REML = FALSE</code> (see the example below), which is an incredibly nice feature forcing less acquainted users to do the test right. However, I have been trying to read most of the documentation for <code>lme4</code> package and cannot find that a notation of this feature (for instance, see <code>?anova.merMod</code>, which directs the user to <code>?vcov.merMod</code>). This makes me confused. </p>
  
  <p>Question: <strong>Why is this feature not clearly mentioned in the documentation?</strong> Have I understood it wrong, perhaps?</p>
  
  <p>Ps. there seems to be a question about this on the <a href="https://stat.ethz.ch/pipermail/r-sig-mixed-models/2008q3/001326.html" rel="nofollow noreferrer">R-mailing lists</a>, but the answers make me even more confused.</p>
  
  <pre><code>library(lme4)
  data(sleepstudy)
  
  reml &lt;- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)
  noreml &lt;- lmer(Reaction ~ Days + (Days | Subject), sleepstudy, REML = F)
  
  reml0 &lt;- lmer(Reaction ~ (Days | Subject), sleepstudy)
  noreml0 &lt;- lmer(Reaction ~ (Days | Subject), sleepstudy, REML = F)
  
  ## Returns similar likelihood ratio test statistics:
  (a &lt;- anova(reml, reml0))
  (b &lt;- anova(noreml, noreml0))
  
  ## Not identical though
  identical(a, b)
  [1] FALSE
  </code></pre>
  
  <p><strong>EDIT:</strong> <code>sessionInfo</code>: <code>R version 3.0.2 (2013-09-25)</code>, <code>lme4_1.0-5</code> </p>