def evaluate_raw(self, y, y_hat, **kwargs):
        n = len(y)
        rmse = (np.nansum((y - y_hat)**2) / n )**.5
        return {"rmse": rmse}
Evaluates the Coefficient of Variation of Root-Mean-Square Error of
dataset/ETHPy150Open impactlab/eemeter/eemeter/meter/fitness.py/RMSE.evaluate_raw