# derivation

## A general model for the bias in variant effect sizes due to population structure

Motivation The effects of population structure in GWAS (genome-wide association studies) have been well-studied. It’s one of those problems that on a surface level is quite easy to grasp intuitively.

## Effect size of a tag variant

Motivation Ever wondered why the effect size of a tag variant is $$r\beta_{causal}$$? Here, $$r$$ is the correlation (measure of LD) between the tag and causal variant, and $$\beta_{causal}$$ is the effect size of the causal variant.