Conditional Path Analysis in Singly-Connected Path Diagrams
We extend the classical path analysis by showing that, for a singly-connected path diagram, the partial covariance of two random variables factorizes over the nodes and edges in the path between the variables. This result allows us to give an alternative explanation to some causal phenomena previously discussed by Pearl (2013), and to show that Simpson's paradox cannot occur in singly-connected path diagrams.
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