VanderWeele, Tyler J.; Robins, James M. - In: Journal of the Royal Statistical Society Series B 72 (2010) 1, pp. 111-127
Formal rules governing signed edges on causal directed acyclic graphs are described and it is shown how these rules can be useful in reasoning about causality. Specifically, the notions of a monotonic effect, a weak monotonic effect and a signed edge are introduced. Results are developed...