1[2 {"id":"C1","text":"The OLS Okun coefficient over 1960Q1-2019Q4 (n=240) is about -0.256 pp of unemployment per 1% quarterly (non-annualised) real GDP growth, with intercept about 0.184 pp and R² about 0.41.","results_keys":["beta_hat","alpha_hat","r_squared","n_analysed","first_quarter","last_quarter"],"status":"supported","caveat":"Linear projection on current-vintage data; not a causal or structural estimate."},3 {"id":"C2","text":"The Newey-West (Bartlett, 4 lags) HAC standard error is about 0.036, roughly 1.8 times the conventional iid SE of about 0.020, reflecting positive residual autocorrelation (lag-1 about 0.39).","results_keys":["se_hac","se_iid","hac_lags","residual_autocorr_lag1"],"status":"supported","caveat":"Bandwidth chosen by the Newey-West (1994) plug-in rule floor(4(T/100)^(2/9)); SE ranges 0.029-0.037 across 0-12 lags (se_hac_by_lags)."},4 {"id":"C3","text":"The Okun coefficient is negative and significantly different from zero at the 5% level using the HAC SE: 95% CI about [-0.326, -0.186], t about -7.1.","results_keys":["okun_negative_5pct","beta_ci_low","beta_ci_high","t_hac","p_value_hac"],"status":"supported","caveat":"Normal (asymptotic) critical values; conclusion robust to all bandwidths examined."},5 {"id":"C4","text":"Mean quarterly real GDP growth over the sample is about 0.75% (non-annualised).","results_keys":["mean_growth"],"status":"supported","caveat":"Current vintage GDP data."}6]7