Graphical Markov Models with Mixed Graphs in R

Authors

Kayvan Sadeghi, University of Oxford
Giovanni M. Marchetti, University of Florence

Date of this Version

12-2012

Document Type

Article

Citation

The R Journal (December 2012) 4(2)

Comments

Copyright 2012, The R Foundation. Open access material. License: CC BY 3.0 Unported

Abstract

In this paper we provide a short tuto rial illustrating the new functions in the package ggm that deal with ancestral, summary and ribbonless graphs. These are mixed graphs (containing three types of edges) that are important because they capture the modified independence structure after marginalisation over, and conditioning on, nodes of directed acyclic graphs. We provide functions to verify whether a mixed graph implies that A is independent of B given C for any disjoint sets of nodes and to generate maximal graphs inducing the same independence structure of non-maximal graphs. Finally, we provide functions to decide on the Markov equivalence of two graphs with the same node set but different types of edges.