title: Scikit Learn PolynomialFeatures - what is the use of the include_bias option?
body: <p>In scikit-learn's PolynomialFeatures preprocessor, there is an option to include_bias. This essentially just adds a column of ones to the dataframe. I was wondering what the point of having this was. Of course, you can set it to False. But theoretically how does having or not having a column of ones along with the Polynomial Features generated affect Regression.</p>
  
  <p>This is the explanation in the documentation, but I can't seem to get anything useful out of it relation to why it should be used or not.</p>
  
  <blockquote>
    <p><strong>include_bias : boolean</strong> </p>
    
    <p>If True (default), then include a bias column, the feature in which
    all polynomial powers are zero (i.e. a column of ones - acts as an
    intercept term in a linear model).</p>
  </blockquote>