Table 1.

Mean Bias in Level 2 Standard Errors Across Varying Simulated Conditions for Continuous and Dichotomous Predictors by Analytic Technique (1,000 Replications Each).

Number of clusters	Cluster size	ICC = .05						ICC = .10
		Continuous			Dichotomous			Continuous			Dichotomous
		OLS	MLM	CB	OLS	MLM	CB	OLS	MLM	CB	OLS	MLM	CB
10	10	−10.3	2.0	47.7	−6.8	6.5	13.3	−27.7	−4.1	43.4	−26.0	−1.3	10.9
	30	−23.3	−4.4	31.7	−18.6	1.6	7.9	−50.1	−9.0	28.7	−46.7	−2.7	7.1
	50	−27.2	−2.3	26.9	−26.8	−1.8	2.1	−56.9	−6.2	24.5	−55.9	−4.1	2.0
20	10	−10.6	−1.0	−3.7	−8.4	1.3	−5.7	−27.2	−4.3	−3.7	−26.7	−3.5	−7.4
	30	−22.5	−5.7	−5.4	−15.5	3.2	−1.3	−47.6	−5.2	−3.8	−44.2	1.6	−2.1
	50	−29.7	−4.4	−4.1	−28.0	−2.1	−6.0	−57.6	−4.9	−4.8	−55.8	−0.9	−4.7
30	10	−9.6	−0.7	−4.1	−4.7	4.6	−0.4	−26.6	−3.3	−4.6	−22.3	2.2	−0.4
	30	−17.4	1.7	−0.9	−20.7	−2.6	−5.6	−45.5	0.6	−1.4	−48.0	−4.2	−7.0
	50	−28.7	−3.1	−4.5	−27.3	−1.0	−4.1	−56.8	−3.0	−4.1	−56.3	−2.1	−4.8
Number of clusters	Cluster size	ICC = .20						ICC = .30
		Continuous			Dichotomous			Continuous			Dichotomous
		OLS	MLM	CB	OLS	MLM	CB	OLS	MLM	CB	OLS	MLM	CB
10	10	−45.4	−5.9	39.0	−44.9	−4.5	8.6	−54.3	−6.0	36.7	−54.2	−5.2	7.4
	30	−66.9	−9.7	26.7	−64.4	−3.0	6.9	−73.5	−10.0	26.0	−71.4	−2.9	6.8
	50	−72.5	−7.2	23.1	−71.6	−3.9	2.1	−78.3	−7.5	22.6	−77.5	−3.9	2.2
20	10	−44.7	−4.9	−4.1	−44.5	−4.0	−8.0	−53.4	−5.1	−4.3	−53.2	−3.9	−8.1
	30	−64.3	−4.0	−2.6	−62.6	1.0	−2.8	−71.0	−3.5	−2.2	−69.8	0.7	−3.1
	50	−72.4	−5.1	−5.2	−71.0	−0.2	−4.1	−77.9	−5.2	−5.3	−76.6	0.1	−3.9
30	10	−43.7	−2.7	−4.1	−40.9	1.9	−0.7	−52.2	−2.2	−3.6	−50.1	1.7	−0.8
	30	−63.2	0.2	−1.6	−64.9	−4.6	−7.5	−70.1	0.0	−1.7	−71.5	−4.7	−7.6
	50	−71.7	−3.0	−3.8	−71.4	−2.1	−4.6	−77.2	−3.0	−3.7	−76.9	−2.0	−4.4

Note. OLS = ordinary least squares; MLM = multilevel model estimated with restricted maximum likelihood using a Kenward–Roger (Kenward & Roger, 1997) standard error adjustment; CB = cluster bootstrapped standard errors using 1,000 replicates; ICC = intraclass correlation coefficient.