MTAG is the efficient generalized method of moments (GMM) estimator based on the moment condition E(β^j−ωtωttβj,t)=0, where ωt is a vector equal to the tth column of Ω and ωtt is a scalar equal to the tth diagonal element of Ω. This equality is a necessary condition derived from the best linear prediction of the vector of GWAS estimates, β^j, from the SNP’s true effect on a single trait, βj,t.
