Confounding of Three Binary-Variable Counterfactual Model with DAG

Jingwei Liu, Shuang Hu

School of Mathematics and System Sciences, Beihang University, Beijing, China.

DOI: 10.4236/am.2013.410189                

Abstract

Confounding of three binary-variable counterfactual model with directed acyclic graph (DAG) is discussed in this paper. According to the effect between the control variable and the covariate variable, we investigate three causal counterfactual models: the control variable is independent of the covariate variable, the control variable has the effect on the covariate variable and the covariate variable affects the control variable. Using the ancillary information based on conditional independence hypotheses and ignorability, the sufficient conditions to determine whether the covariate variable is an irrelevant factor or whether there is no confounding in each counterfactual model are obtained.

Keywords

Causal Effect; Independence Hypothesis; Counterfactual Model; Confounding Bias; Irrelevant; Ancillary Information; Directed Acyclic Graph

Conflicts of Interest

The authors declare no conflicts of interest.

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