1[2 {"id":"C1","text":"Ridge (lambda=50) reduces out-of-sample RMSE relative to the naive forecast by about 36% (RMSE 0.561 vs 0.883).","results_keys":["rmse_ridge","rmse_naive","rel_improvement_vs_naive"],"status":"supported","caveat":"Current-vintage data, publication lags ignored; DM p≈0.001 (supplementary)."},3 {"id":"C2","text":"Ridge does not beat the expanding historical mean: RMSE is about 3.1% higher (0.561 vs 0.544), and MAE is also higher.","results_keys":["rmse_ridge","rmse_mean","rel_improvement_vs_mean","mae_ridge","mae_mean"],"status":"supported","caveat":"The difference is not statistically significant (DM p≈0.59; bootstrap 95% CI [-0.16, 0.06])."},4 {"id":"C3","text":"Standardisation statistics and target mean were computed from each origin's training window only (expanding).","results_keys":["normalisation_window","n_analysed"],"status":"supported","caveat":"None."}5]6