MR Dictionary

Relevance assumption

Synonyms: IV1 assumption, first MR assumption

This is the first of the core IV assumptions which states that the IV must be associated with the risk factor of interest. 

In MR the aim is to select genetic variants that have been shown to be robustly associated with the risk factor of interest. In most MR studies, this means genetic variants that are associated with an exposure at genome-wide significance and replicated in several independent study samples from the population of interest. The statistical strength of the genetic instrument-risk factor association if ‘weak’ can result in weak instrument bias


Other terms in 'Sources of bias and limitations in MR':