1[2 {"id":"C1","text":"Over 1960Q1-2019Q4 (240 quarters) the OLS Okun coefficient is about -0.256 pp of unemployment per 1% of quarterly real GDP growth, with intercept 0.184 pp and R^2 0.408.","results_keys":["beta_hat","alpha_hat","r_squared","n_analysed","first_quarter","last_quarter"],"status":"supported","caveat":"Contemporaneous linear projection, current-vintage data; not causal."},3 {"id":"C2","text":"With a Newey-West Bartlett HAC SE (4 lags, Newey-West 1994 rule) of 0.0358, the 95% CI is [-0.326, -0.186] and the coefficient is negative and significant at the 5% level.","results_keys":["se_hac","hac_lags","beta_ci_low","beta_ci_high","okun_negative_5pct","t_hac","p_value_hac"],"status":"supported","caveat":"Asymptotic normal critical values; no small-sample correction."},4 {"id":"C3","text":"The naive iid SE (0.0200) understates uncertainty roughly 1.8-fold relative to the HAC SE, consistent with positive residual autocorrelation (0.39 at lag 1).","results_keys":["se_iid","se_hac","resid_lag1_autocorr","baseline_ci_iid_low","baseline_ci_iid_high"],"status":"supported","caveat":""},5 {"id":"C4","text":"The significance conclusion is robust to HAC bandwidths from 0 to 12 lags.","results_keys":["se_hac_sensitivity_by_lags","beta_hat"],"status":"supported","caveat":"Only a fixed grid of bandwidths was checked."},6 {"id":"C5","text":"Mean quarterly real GDP growth over the sample is 0.754% (not annualised), close to the implied unemployment-stabilising growth rate alpha/|beta| of about 0.72%.","results_keys":["mean_growth","alpha_hat","beta_hat"],"status":"supported","caveat":"The ratio is derived arithmetic, not a separate estimate with its own uncertainty."}7]8