Table 3.

Relative bias (RB), standard error (SE) and mean squared error (MSE) of the IPW and SICO estimation under Models (2) and (3) with two sampling schemes. IPW is the estimates using inverse probability weighting; and SICO(m) is the SICO estimates with m replicate.

Sampling	Estimation	τ = 0.5			τ = 0.9
		RB (%)	SE	MSE × n	RB (%)	SE	MSE × n
Model 2: Discrete X and Chi-square error
Oversample X = 2	IPW	1.5	0.025	1.3	0.5	0.097	18.9
	SICO (m=10)	1.2	0.025	1.3	−2.1	0.097	18.8
Oversample W > 0	IPW	−18.6	0.147	44.3	−106.0	0.312	251.0
	SICO (m=10)	−0.8	0.026	1.3	−1.0	0.102	20.7
Model 3: Continuous X and Normal error
Oversample X > 5	IPW	16.7	0.029	2.4	18.1	0.035	3.9
	SICO (m=10)	11.8	0.028	2.0	12.8	0.035	3.2
Oversample W > 0	IPW	10.0	0.039	3.4	3.7	0.053	5.6
	SICO (m=10)	−0.4	0.031	1.9	−2.8	0.038	2.9