title: Could we do backward elimination with mixed model using lmer
body: <p>I used the following syntax for the mixed model and then step but it did not work. </p>
  
  <p>Does it normally work like this or I actually can not use backward elimination with lmer? Thanks!</p>
  
  <pre><code>fullmodel&lt;-lmer(Eeff~NDF+ADF+CP+NEL+DMI+FCM + (1|Study),data=na.omit(phuong))
  step(fullmodel, direction = "backward", trace=FALSE ) 
  </code></pre>