isGident                 package:ggm                 R Documentation

_G-_i_d_e_n_t_i_f_i_a_b_i_l_i_t_y _o_f _a_n _U_G

_D_e_s_c_r_i_p_t_i_o_n:

     Tests if an undirected graph is G-identifiable.

_U_s_a_g_e:

     isGident(amat)

_A_r_g_u_m_e_n_t_s:

    amat: a symmetric matrix with dimnames representing the adjacency
          matrix of an undirected graph

_D_e_t_a_i_l_s:

     An undirected graph is said G-identifiable if every connected
     component of the complementary graph contains an odd cycle
     (Stanghellini and Wermuth, 2003). See also Tarantola and Vicard
     (2002).

_V_a_l_u_e:

     a logical value, 'TRUE' if the graph is G-identifiable and 'FALSE'
     if it is not.

_A_u_t_h_o_r(_s):

     Giovanni M. Marchetti

_R_e_f_e_r_e_n_c_e_s:

     Stanghellini, E. & Wermuth, N. (2003). On the identification of
     path-analysis models with one hidden variable. Submitted and
     available at <URL: http://psystat.sowi.uni-mainz.de>.

     Stanghellini, E. (1997). Identification of a single-factor model
     using graphical Gaussian rules. _Biometrika_, 84, 241-244.

     Tarantola, C. & Vicard, P. (2002). Spanning trees and
     identifiability of a single-factor model. _Statistical Methods &
     Applications_, 11, 139-152.

     Vicard, P. (2000). On the identification of a single-factor model
     with correlated residuals. _Biometrika_, 87, 199-205.

_S_e_e _A_l_s_o:

     'UG', 'cmpGraph', 'cycleMatrix'

_E_x_a_m_p_l_e_s:

     ## A not G-identifiable UG
     G1 <- UG(~ a*b + u*v)
     isGident(G1)
     ## G-identifiable UG
     G2 <- UG(~ a + b + u*v)
     isGident(G2)
     ## G-identifiable UG
     G3 <- cmpGraph(UG(~a*b*c+x*y*z))
     isGident(G3)

