title: Combine two plots in one graph using ciplot
body: <p>I would like to plot the means and confidence intervals of two variables into one graph. I used <code>ciplot</code> to do this for only one variable, but for two this code is not working. </p>
  
  <p>On the internet I found that you could combine the plots as follows:</p>
  
  <pre><code>ciplot relative_ambition12 relative_ambition22, by(quota)
  </code></pre>
  
  <p>However, if I run this I get the error:</p>
  
  <blockquote>
    <p>no observations found </p>
  </blockquote>
  
  <p>At the same time both of the following do produce graphs: </p>
  
  <pre><code>ciplot relative_ambition12, by(quota) 
  </code></pre>
  
  <p></p>
  
  <pre><code>ciplot relative_ambition22, by(quota)
  </code></pre>
  
  <p>Does anyone know how I can combine these two graphs into one?</p>