title: fixed effects regression with felm
body: <p>I am wondering why my fixed effects regression does not work.</p>
  
  <p>My Code is the following:</p>
  
  <pre><code>sfeL=felm(sätzegesp~TTRverf,spieler|0|0, data=datregT)
  </code></pre>
  
  <p><code>sätzegesp</code> is a vector if numbers, <code>TTRverf</code> is a dummy-variable and the fixed effect variable <code>spieler</code> is a vector of numbers indicating the ID of each person.</p>
  
  <p>Unfortunately, I get the error</p>
  
  <blockquote>
    <p>operators are only possible for numeric, logical or complex types</p>
  </blockquote>