def get_adcm(self):
        """
        Absolute deviation around class median (ADCM).

        Calculates the absolute deviations of each observation about its class
        median as a measure of fit for the classification method.

        Returns sum of ADCM over all classes
        """
        adcm = 0
        for class_def in self.classes:
            if len(class_def) > 0:
                yc = self.y[class_def]
                yc_med = np.median(yc)
                ycd = np.abs(yc - yc_med)
                adcm += sum(ycd)
        return adcm