Wald ratio estimate

Synonyms: Ratio estimate

Causal estimate obtained for a single genetic variant by dividing its gene-outcome association by its gene-exposure association. 

Genetic variants must satisfy the IV assumptions. Equivalent to TSLS (and its approximate binary/time-to-event outcome) variants with one instrument. 

References

• Burgess S, Small DS, Thompson SG. A review of instrumental variable estimators for Mendelian randomization. Stat Methods Med Res 2015.

Other terms in 'Two-sample MR methods':

• Inverse variance weighted (IVW) fixed effect estimate
• Maximum likelihood-based MR
• Summary MR (SMR)
• Unweighted regression