Table 3. Simulation study settings.

		Sample sizes			Covariates
Scenario	Population	Study 1	Study 2	Study 3	Study 1	Study 2	Study 3
1	EUR	1600	2200	3200	$\left(z_1,z_2\right)$	$\left(z_1,z_2\right)$	$\left(z_1,z_2\right)$
2	EUR	1600	2200	3200	$z_1$	$\left(z_1,z_2\right)$	$\left(z_1,z_2,z_3\right)$
3	EUR + AA	1600	2200	3200	$z_1$	$\left(z_1,z_2\right)$	$\left(z_1,z_2,z_3\right)$

Sample sizes are total sample sizes in each study. Covariates represent covariates in each study. EUR refers to the scenario where all three studies had EUR samples. EUR + AA refers to the scenario where studies 1 and 2 had EUR samples and study 3 had AA samples. $z_1$ is a binary covariate taking values 0 and 1 each with probability 0.5, and $z_2$ and $z_3$ are continuous covariates and distributed as standard normal.