title: Why can't I import statsmodels directly?
body: <p>I'm certainly missing something very obvious here, but why does this work:</p>
  
  <pre><code>a = [0.2635,0.654654,0.365,0.4545,1.5465,3.545]
  
  import statsmodels.robust as rb
  print rb.scale.mad(a)
  0.356309343367
  </code></pre>
  
  <p>but this doesn't:</p>
  
  <pre><code>import statsmodels as sm
  print sm.robust.scale.mad(a)
  ---------------------------------------------------------------------------
  AttributeError                            Traceback (most recent call last)
  &lt;ipython-input-5-1ce0c872b0be&gt; in &lt;module&gt;()
  ----&gt; 1 print statsmodels.robust.scale.mad(a)
  
  AttributeError: 'module' object has no attribute 'robust'
  </code></pre>