title: Plotting predicted values from lmer as a single plot
body: <p>I am working on graphing the predicted values from a multilevel model  (using the lme4 package). I am able to do this successfully using the <code>Effect()</code> function. As shown below:</p>
  
  <pre><code>library(lme4)
  library(effects)
  m1=lmer(price~depth*cut+(1|cut),diamonds)
  plot(Effect(c("cut","depth"),m1))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/BcZiD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BcZiD.png" alt="enter image description here"></a></p>
  
  <p>But, I want to present these same data as a single plot with a legend. Using ggplots, I can do this; but, I lose the error bars, as shown below:</p>
  
  <pre><code>ggplot(data.frame(Effect(c("cut","depth"),m1)),
         aes(x=depth,y=fit,color=cut,group=cut))+
    geom_line()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/NiD0z.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NiD0z.png" alt="enter image description here"></a></p>
  
  <p><em>How can I recreate the first plot (with error bars) as a single plot?</em></p>