public static double transformedRmse(double[] obs, double[] sim) {
        sameArrayLen(sim, obs);
        double error = 0;
        double z_pred = 0.;
        double z_val = 0.;
        for (int i = 0; i < sim.length; i++) {
            z_pred = (Math.pow((1.0 + sim[i]), 0.3) - 1.0) / 0.3;
            z_val = (Math.pow((1.0 + obs[i]), 0.3) - 1.0) / 0.3;
            error += (z_pred - z_val) * (z_pred - z_val);
        }
        return Math.sqrt(error / sim.length);
    }