Enhancing Identification of Causal Effects by Pruning
This work addresses inefficiencies in causal inference for researchers and practitioners, though it is incremental as it builds on existing identifiability algorithms.
The paper tackles the problem of causal effect identification by detecting and removing redundant variables from complex expressions, which reduces computational burden and improves estimation accuracy in the presence of measurement error or missing data.
Causal models communicate our assumptions about causes and effects in real-world phe- nomena. Often the interest lies in the identification of the effect of an action which means deriving an expression from the observed probability distribution for the interventional distribution resulting from the action. In many cases an identifiability algorithm may return a complicated expression that contains variables that are in fact unnecessary. In practice this can lead to additional computational burden and increased bias or inefficiency of estimates when dealing with measurement error or missing data. We present graphical criteria to detect variables which are redundant in identifying causal effects. We also provide an improved version of a well-known identifiability algorithm that implements these criteria.