Synonyms: Median-based estimate

Defined as the 50th percentile of either an unweighted or inverse variance weighted empirical density function of the Wald ratio (or Ratio estimates).

Requires that at least 50% of the weight in the analysis stems from variants that are valid instruments. Can be either unweighted or, traditionally, weighted by the inverse variance of the SNP-outcome association but may be weighted using other methods.

## References