is.Gident {ggm} | R Documentation |
Tests if an undirected graph is G-identifiable.
is.Gident(gmat)
gmat |
a symmetric matrix with dimnames representing the edge matrix of an undirected graph |
An undirected graph is G-identifiable if every connected component of the complementary graph contains an odd cycle (cfr. Stanghellini and Wermuth, 2003). The algorithm used follows suggestions by Tarantola and Vicard (2002).
a logical value, TRUE
if the graph is G-identifiable and
FALSE
if it is not.
Giovanni M. Marchetti
Stanghellini, E. & Wermuth, N. (2003). On the identification of directed acyclic graph models with one hidden variable. Submitted and available at http://psystat.sowi.uni-mainz.de.
Stanghellini, E. (1997). Identification of a single-factor model using graphical Gaussian rules. Biometrika, 87, 199205.
Tarantola, C. & Vicard, P. (2002). Spanning trees and identifiability of a single-factor model. Statistical Methods & Applications, 11, 139152.
Vicard, P. (2000). On the identification of a single-factor model with correlated residuals. Biometrika, 87, 199205.
## A not G-identifiable UG G1 <- UG(~ a*b + u*v) is.Gident(G1) ## G-identifiable UG G2 <- UG(~ a + b + u*v) is.Gident(G2)