       </p>
<p>
          The following graph illustrate how the PDF varies as the success fraction
          <span class="emphasis"><em>p</em></span> changes:
        </p>
<p>
          <span class="inlinemediaobject"><img src="../../../../graphs/negative_binomial_pdf_1.svg" align="middle"></span>
        </p>
<p>
          Alternatively, this graph shows how the shape of the PDF varies as the
          number of successes changes:
        </p>
<p>
          <span class="inlinemediaobject"><img src="../../