MR Dictionary

Regression dilution bias (attenuation by errors)

Refers to the expected attenuation towards the null of an association due to random measurement error in an exposure. This is particularly likely to occur with exposures that have naturally and widely fluctuating levels, such as blood pressure and (non-fasting) glucose. 

Because genetic variants represent lifetime (or long-term) changes of an exposure, regression dilution bias is less likely in MR studies compared with other methods, such as multivariable regression, a method also commonly used with observational data. Regression dilution bias can happen, though, in situations where the MR assumptions are violated.


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