def PredictivePmf(self, xs, name=''):
        """Makes a predictive distribution.

        xs: values to go into the Pmf

        Returns: Pmf that maps from x to the mean prevalence of x
        """
        alpha0 = self.params.sum()
        ps = self.params / alpha0
        return MakePmfFromItems(zip(xs, ps), name=name)