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Interpreting and using CPDAGs with background knowledge
Proceedings of the 33rd Conference on Uncertainty in Artificial Intelligence, PMLR R15:461-470, 2017.
Abstract
We develop terminology and methods for working with maximally oriented partially directed acyclic graphs (maximal PDAGs). Maximal PDAGs arise from imposing restric- tions on a Markov equivalence class of directed acyclic graphs, or equivalently on its graph- ical representation as a completed partially directed acyclic graph (CPDAG), for exam- ple when adding background knowledge about certain edge orientations. Although maximal PDAGs often arise in practice, causal meth- ods have been mostly developed for CPDAGs. In this paper, we extend such methodology to maximal PDAGs. In particular, we de- velop methodology to read off possible ances- tral relationships, we introduce a graphical cri- terion for covariate adjustment to estimate total causal effects, and we adapt the IDA and joint- IDA frameworks to estimate multi-sets of pos- sible causal effects. We also present a simula- tion study that illustrates the gain in identifia- bility of total causal effects as the background knowledge increases. All methods are imple- mented in the R package pcalg.