The challenging interpretation of instrumental variable estimates under monotonicity.

ABSTRACT:

Background

Instrumental variable (IV) methods are often used to identify 'local' causal effects in a subgroup of the population of interest. Such 'local' effects may not be ideal for informing clinical or policy decision making. When the instrument is non-causal, additional difficulties arise for interpreting 'local' effects. Little attention has been paid to these difficulties, even though commonly proposed instruments in epidemiology are non-causal (e.g. proxies for physician's preference; genetic variants in some Mendelian randomization studies).

Methods

For IV estimates obtained from both causal and non-causal instruments under monotonicity, we present results to help investigators pose four questions about the local effect estimates obtained in their studies. (1) To wha

SUBMITTER: Swanson SA 

PROVIDER: S-EPMC6124612 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature