title: Python - FamaMacBeth, cannot astype a datetimelike from [datetime64[ns]] to [float64]
body: <p>When trying to run a <code>FamaMacBeth</code> regression on my dataset, I get the <code>TypeError</code>:</p>
  <pre><code>cannot astype a datetimelike from [datetime64[ns]] to [float64],
  </code></pre>
  <p>My date column is of type <code>numpy.ndarray</code></p>
  <p>Anyone know what I am doing wrong?</p>