Development of New Robust Optimal Score Function for the Weibull Distributed Error Term in Multilevel Models

Table 6

Bias and MSE of using Weibull, Wilcoxon, and REML methods when  = 6..

		REML		Weibull		Wilcoxon		Precision
N2	N1	Bias	MSE	Bias	MSE	Bias	MSE	Weib/REML	Weib/Wil	Wil/REML
5	5	2.145	1.616	0.223	0.56	2.147	1.955	1.092	1.068	1.21
	10	2.181	2.219	0.214	0.721	2.176	2.429	1.089	1.086	1.095
	20	2.15	3.48	0.236	1.147	2.153	3.653	1.039	1.085	1.05
	40	2.139	6.208	0.236	2.084	2.143	6.413	1.012	1.076	1.033
10	5	2.264	1.212	0.073	0.296	2.266	1.294	1.065	1.091	1.068
	10	2.278	1.561	0.103	0.342	2.268	1.614	1.023	1.086	1.034
	20	2.25	2.273	0.144	0.547	2.245	2.305	1.019	1.014	1.014
	40	2.259	3.79	0.087	0.85	2.261	3.811	1.017	1.09	1.006
20	5	2.337	1.024	0.078	0.254	2.327	1.036	1.007	1.095	1.012
	10	2.31	1.202	0.034	0.235	2.302	1.201	1.093	1.094	0.999
	20	2.319	1.579	0.053	0.327	2.31	1.572	1.099	1.104	0.996
	40	2.328	2.391	0.063	0.496	2.317	2.375	1.097	1.104	0.993
40	5	2.338	0.908	0.022	0.2	2.321	0.906	1.081	1.084	0.998
	10	2.35	1.017	0.023	0.204	2.335	1.006	1.082	1.093	0.989
	20	2.334	1.213	0.03	0.225	2.317	1.198	1.079	1.093	0.988
	40	2.345	1.613	-0.001	0.298	2.328	1.592	1.086	1.1	0.987