   </p></dd>
</dl>
</div>
<p>
          Note that this calculation works with <span class="emphasis"><em>variances</em></span> and
          not <span class="emphasis"><em>standard deviations</em></span>.
        </p>
<p>
          The sign of the parameter <span class="emphasis"><em>difference_from_variance</em></span>
          is important: the Chi Squared distribution is asymmetric, and the caller
          must decide in advance whether they are testing for a variance greater
          than a nominal v