title: Stata xtoverid command error
body: <p>I have panel data and my regression is of the form:</p>
  
  <pre><code>s_roa1 = s_roa + c_roa
  </code></pre>
  
  <p>I am new to Stata and i am trying to use the <code>xtoverid</code> command for a <code>robust hausman test</code> to help me choose between a fixed or random effects model:</p>
  
  <pre><code>xtoverid s_roa1 s_roa c_roa, fe i (year)
  </code></pre>
  
  <p>However, I get the following error:</p>
  
  <pre><code>varlist not allowed
  </code></pre>
  
  <p>Can anyone help me understand what does this suggest?</p>