Table I.

Simulation results (Set I) comparing correlation modeling (M) with conventional assumption of exchangeable correlation of constant magnitude (C). ECP is empirical coverage probability for 95% confidence intervals for β₁. Details of the simulation settings are provided in the text.

Correlation level	Very high			High			Moderate			Low
True β1	0.81	0.90	1.35	0.81	0.90	1.35	0.81	0.90	1.35	0.81	0.90	1.35
Bias (M)	0.01	0.04	0.11	0.05	0.04	0.10	0.01	0.01	0.06	0.01	0.02	0.05
Bias (C)	0.00	0.03	0.10	0.03	0.03	0.03	0.00	0.00	0.02	0.01	0.01	0.02
Rel. Bias (M)	0.01	0.04	0.08	0.06	0.04	0.07	0.01	0.01	0.04	0.01	0.02	0.03
Rel. Bias (C)	0.00	0.03	0.07	0.03	0.04	0.02	0.00	0.00	0.00	0.01	0.01	0.02
Rel. Eff.	0.78	0.84	0.91	0.89	0.87	0.91	0.88	1.00	1.01	1.01	0.99	1.03
Rel. MSE	0.81	0.89	0.95	0.98	0.94	0.99	0.94	1.08	1.06	1.06	1.05	1.10
Emp. power (M)	0.71	0.78	0.93	0.93	0.95	1.00	0.99	1.00	1.00	1.00	1.00	1.00
Emp. power (C)	0.60	0.69	0.86	0.89	0.90	0.98	0.98	0.99	1.00	1.00	1.00	1.00
ECP (M)	0.93	0.95	0.95	0.95	0.95	0.96	0.96	0.96	0.94	0.95	0.94	0.94
ECP (C)	0.95	0.95	0.95	0.94	0.95	0.96	0.95	0.96	0.94	0.95	0.95	0.95