TABLE 1.

The pIVW estimator with various penalty parameter λ. The true causal effect $\beta =0.5$. No horizontal pleiotropy exists ($\tau =0$). No IV selection is conducted. The simulation is based on 10,000 replicates. Bias (%): bias divided by β; CP (%): coverage probability of the 95% confidence interval; SE: empirical standard error

η	λ	Bias	SE	CP
4.33	0	22.4	2.156	94.8
	0.5	3.7	0.341	94.3
	1	−3.3	0.293	94.0
	1.5	−8.3	0.267	93.4
	2	−12.3	0.248	92.8
	2.5	−15.6	0.234	91.9
9.52	0	3.0	0.148	94.8
	0.5	1.3	0.143	94.6
	1	−0.2	0.139	94.6
	1.5	−1.6	0.136	94.4
	2	−2.9	0.133	94.2
	2.5	−4.2	0.130	93.9
21.85	0	0.7	0.069	94.6
	0.5	0.4	0.068	94.5
	1	0.0	0.068	94.5
	1.5	−0.3	0.067	94.4
	2	−0.7	0.067	94.3
	2.5	−1.0	0.067	94.1