def pr_qmean(self):
return qmean((self.precision(), self.recall()))<EOL>
r"""Return quadratic mean of precision & recall.

        The quadratic mean of precision and recall is defined as:
        :math:`\sqrt{\frac{precision^{2} + recall^{2}}{2}}`

        Cf. https://en.wikipedia.org/wiki/Quadratic_mean

        Returns
        -------
        float
            The quadratic mean of the confusion table's precision & recall

        Example
        -------
        >>> ct = ConfusionTable(120, 60, 20, 30)
        >>> ct.pr_qmean()
        0.8290638930598233