Application of Seemingly Unrelated Regression in Medical Data with Intermittently Observed Time-Dependent Covariates

Table 5

Simulation results (summary of estimated parameters, bias, and MSE) for intermittent observation of time-dependent covariates (situation 9 from Table 1) with different sample sizes (𝑛=20,60,120, and 240).

Parameter; (true value)	Method	Sample size = 20			Sample size = 60			Sample size = 120			Sample size = 240
		^↼𝛽	Bias	MSE	^↼𝛽	Bias	MSE	^↼𝛽	Bias	MSE	^↼𝛽	Bias	MSE
𝛽2; (−1.13)	SURCC	−.95	.18	6.64	−1.14	−.01	1.86	−1.12	.01	.83	−1.13	−.003	.43
	MRMCC	−.99	.14	7.43	−1.16	−.03	2.007	−1.13	.002	.89	−1.14	−.01	.46
	SURBOCF	−1.04	.09	7.90	−1.14	−.01	1.92	−1.12	.008	.83	−1.14	−.006	.42
	MRMBOCF	−1.03	.10	6.53	−1.16	−.03	1.85	−1.12	.006	.82	−1.14	−.01	.42
	SURLOCF	−1.04	.09	7.90	−1.14	−.01	1.92	−1.12	.008	.83	−1.14	−.006	.42
	MRMLOCF	−1.03	.10	6.53	−1.16	−.03	1.85	−1.12	.006	.82	−1.14	−.01	.42
𝛽3; (.23)	SURCC	.20	−.03	6.77	.14	−.09	1.90	.20	−.02	.88	.24	.007	.44
	MRMCC	.20	−.02	6.70	.12	−.11	2.008	.19	−.04	.93	.23	−.002	.45
	SURBOCF	.24	.01	7.53	.14	−.08	1.93	.21	−.02	.87	.24	.01	.42
	MRMBOCF	.17	−.05	5.95	.12	−.11	1.85	.19	−.03	.86	.24	.01	.43
	SURLOCF	.24	.01	7.53	.14	−.08	1.93	.21	−.02	.87	.24	.01	.42
	MRMLOCF	.17	−.05	5.95	.12	−.11	1.85	.19	−.03	.86	.24	.01	.43
𝛽4; (−.01)	SURCC	−.11	−.10	1.58	−.007	.003	.41	−.02	−.01	.20	−.02	−.005	.09
	MRMCC	−.02	−.008	4.16	.01	.003	1.13	−.03	−.02	.56	−.02	−.02	.25
	SURBOCF	.02	.03	4.10	.02	.02	.93	−.007	.002	.46	−.01	−.001	.20
	MRMBOCF	−.03	−.02	3.38	.02	.03	.88	.002	.01	.44	.005	.01	.20
	SURLOCF	.02	.03	4.10	.02	.02	.93	−.007	.002	.46	−.01	−.001	.20
	MRMLOCF	−.03	−.02	3.38	.02	.03	.88	.002	.01	.44	.005	.01	.20
𝛽5; (−1.12)	SURCC	−.19	.93	2.02	−.28	.84	1.001	−.27	.85	.86	−.26	.86	.80
	MRMCC	−1.14	−.02	2.89	−1.16	−.04	.77	−1.09	.03	.37	−1.10	.02	.18
	SURBOCF	−1.05	.07	2.82	−1.02	−.09	.71	−.96	.15	.34	−.99	.13	.17
	MRMBOCF	−.95	.16	2.27	−.97	.15	.65	−.92	.20	.35	−.94	.18	.18
	SURLOCF	−1.05	.07	2.82	−1.02	−.09	.71	−.96	.15	.34	−.99	.13	.17
	MRMLOCF	−.95	.16	2.27	−.97	.15	.65	−.92	.20	.35	−.94	.18	.18

*Note: SUR_CC,MRM_CC,SUR_BOCF,MRM_BOCF,SUR_LOCF,  and MRM_LOCF represent the estimated parameters from MRM and SUR models under complete case (CC) analysis, baseline observation carried forward (BOCF), and last observation carried forward (LOCF) method, respectively.