stresscent                package:sna                R Documentation

_C_o_m_p_u_t_e _t_h_e _S_t_r_e_s_s _C_e_n_t_r_a_l_i_t_y _S_c_o_r_e_s _o_f _N_e_t_w_o_r_k _P_o_s_i_t_i_o_n_s

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

     'stresscent' takes a graph stack ('dat') and returns the stress
     centralities of positions within one graph (indicated by 'nodes'
     and 'g', respectively).  Depending on the specified mode, stress
     on directed or undirected geodesics will be returned; this
     function is compatible with 'centralization', and will return the
     theoretical maximum absolute deviation (from maximum) conditional
     on size (which is used by 'centralization' to normalize the
     observed centralization score).

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

     stresscent(dat, g=1, nodes=c(1:dim(dat)[2]), gmode="digraph", 
         diag=FALSE, tmaxdev=FALSE, cmode="directed", 
         geodist.precomp=NULL, rescale=FALSE)

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

     dat: Data array to be analyzed.  By assumption, the first
          dimension of the array indexes the graph, with the next two
          indexing the actors. Alternately, this can be an n x n matrix
          (if only one graph is involved). 

       g: Integer indicating the index of the graph for which
          centralities are to be calculated.  By default, 'g==1'. 

   nodes: List indicating which nodes are to be included in the
          calculation.  By default, all nodes are included. 

   gmode: String indicating the type of graph being evaluated. 
          '"digraph"' indicates that edges should be interpreted as
          directed; '"graph"' indicates that edges are undirected. 
          'gmode' is set to '"digraph"' by default.

    diag: Boolean indicating whether or not the diagonal should be
          treated as valid data.  Set this true if and only if the data
          can contain loops.  'diag' is 'FALSE' by default. 

 tmaxdev: Boolean indicating whether or not the theoretical maximum
          absolute deviation from the maximum nodal centrality should
          be returned.  By default, 'tmaxdev==FALSE'. 

   cmode: String indicating the type of betweenness centrality being
          computed (directed or undirected geodesics). 

geodist.precomp: A 'geodist' object precomputed for the graph to be
          analyzed (optional)  

 rescale: If true, centrality scores are rescaled such that they sum to
          1. 

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

     The stress of a vertex, v, is given by


              C_S(v) = sum( g_ivj, i,j: i!=j,i!=v,j!=v)


     where g_ijk is the number of geodesics from i to k through j. 
     Conceptually, high-stress vertices lie on a large number of
     shortest paths between other vertices; they can thus be thought of
     as ``bridges'' or ``boundary spanners.''  Compare this with
     'betweenness', which weights shortest paths by the inverse of
     their redundancy.

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

     A vector of centrality scores

_N_o_t_e:

     Judicious use of 'geodist.precomp' can save a great deal of time
     when computing multiple path-based indices on the same network.

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

     Carter T. Butts buttsc@uci.edu

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

     'centralization'

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

     g<-rgraph(10)     #Draw a random graph with 10 members
     stresscent(g)     #Compute stress scores

