Plots histogram of the discrepancy from draws of the posterior

        Parameters
        ----------
        nsims : int (default : 1000)
            How many draws for the PPC

        T : function
            A discrepancy measure - e.g. np.mean, np.std, np.max

def plot_ppc(self, nsims=1000, T=np.mean, **kwargs):
        """ Plots histogram of the discrepancy from draws of the posterior

        Parameters
        ----------
        nsims : int (default : 1000)
            How many draws for the PPC

        T : function
            A discrepancy measure - e.g. np.mean, np.std, np.max
        """     
        if self.latent_variables.estimation_method not in ['BBVI', 'M-H']:
            raise Exception("No latent variables estimated!")
        else:
            import matplotlib.pyplot as plt
            import seaborn as sns

            figsize = kwargs.get('figsize',(10,7))

            lv_draws = self.draw_latent_variables(nsims=nsims)
            sigmas = [self._model(lv_draws[:,i])[0] for i in range(nsims)]
            data_draws = np.array([fam.Skewt.draw_variable(loc=self.latent_variables.z_list[-2].prior.transform(lv_draws[-2,i]),
                shape=self.latent_variables.z_list[-3].prior.transform(lv_draws[-3,i]), 
                skewness=self.latent_variables.z_list[-4].prior.transform(lv_draws[-4,i]), nsims=len(sigmas[i]), scale=np.exp(sigmas[i]/2.0)) for i in range(nsims)])
            T_sim = T(self.sample(nsims=nsims), axis=1)
            T_actual = T(self.data)

            if T == np.mean:
                description = " of the mean"
            elif T == np.max:
                description = " of the maximum"
            elif T == np.min:
                description = " of the minimum"
            elif T == np.median:
                description = " of the median"
            else:
                description = ""

            plt.figure(figsize=figsize)
            ax = plt.subplot()
            ax.axvline(T_actual)
            sns.distplot(T_sim, kde=False, ax=ax)
            ax.set(title='Posterior predictive' + description, xlabel='T(x)', ylabel='Frequency');
            plt.show()