1[2 {"id":"C1","text":"At h=1 the AR(2)-on-differences model does not beat the naive forecast: RMSE 0.1199 vs 0.1171 (relative improvement -0.023).","results_keys":["rmse_model_h1","rmse_naive_h1","rel_improvement_rmse_h1","n_evaluated_h1"],"status":"supported","caveat":"35 evaluated pairs, final-vintage data; DM-HLN p=0.017 but economically negligible difference."},3 {"id":"C2","text":"At h=3 the model does not beat the naive forecast: RMSE 0.1598 vs 0.1586 (relative improvement -0.008), difference not statistically significant.","results_keys":["rmse_model_h3","rmse_naive_h3","rel_improvement_rmse_h3","n_evaluated_h3"],"status":"supported","caveat":"DM-HLN p=0.18; small sample."},4 {"id":"C3","text":"MAE ranks the forecasts the same way: the naive forecast has lower MAE at both horizons.","results_keys":["mae_naive_h1","mae_model_h1","mae_naive_h3","mae_model_h3"],"status":"supported","caveat":"Differences are a few thousandths of a percentage point."},5 {"id":"C4","text":"The finding of no improvement holds up when COVID-2020 differences are excluded from estimation (model becomes worse, especially at h=3).","results_keys":[],"status":"supported","caveat":"Sensitivity analysis not pre-specified; numbers in out/supplementary.json, not in results.json."},6 {"id":"C5","text":"The 2025-10 missing observation is excluded from evaluation, leaving 35 evaluated pairs per horizon.","results_keys":["n_evaluated_h1","n_evaluated_h3","data_issues"],"status":"supported","caveat":""}7]8