Table 1 Accuracy of method for correctly testing for the presence of different levels of effect modification over 1,000 iterations. This simulation explored the use of the test to detect differences between a single sex GWAS and a mixed-sex population GWAS for a single instrument. The simulation therefore emulates settings where the outcome GWAS has been measured in a specific sex (e.g. male fertility) but where the explore need not be sex specific (e.g. genetically predicted PDE5 levels) [24]. Accuracy in the 0% change in effect setting represents the percentage of iterations in which the test fails to detect a difference. In all other settings it represents the percentage of iterations in which the test detects a difference. Similar results were found in a simulation with many SNPs (Supplementary Table 1)

From: MRSamePopTest: introducing a simple falsification test for the two-sample mendelian randomisation ‘same population’ assumption