print('nSSE, SST, SSR, and RMSE:')
mean_y = np.mean(y_output)
sst = np.sum((y_output - mean_y)**2)
sse = sst - results.ssr
print('SSE: {}'.format(sse))
print('SST: {}'.format(sst))
print('SSR: {}'.format(results.ssr))
print('RMSE: {}'.format(np.sqrt(results.mse_resid))) # ESHx