title: Does this middle variable have any information gain?
body: <p>Let's say that I have 2 variables: <code>A</code> (as the input) and <code>C</code> (as the output)<br>
  So it's <code>A -&gt; C</code><br>
  There's also another variable <code>B</code>, and<br>
  <code>corr(A, B) &gt; corr(A, C)</code><br>
  <code>corr(C, B) &gt; corr(A, C)</code><br><br>
  Would <code>A -&gt; B -&gt; C</code> get better performance with the existing model?<br>
  In other words, does this <code>B</code> have any information gain?</p>