tabdev                package:labdsv                R Documentation

_T_a_b_l_e _D_e_v_i_a_n_c_e

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

     Calculates the species (column-wise) and total deviance of a
     classified vegetation data frame

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

     veg,clustering,nitr=1000)

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

     veg: a vegetation (or other taxon) data frame

clustering: an integer vector specifying class membership  for each
          plot

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

     Calculates the relative abundance of taxa in classes, and then 
     calculates the deviance associated with that taxon.  Total table
     deviance is simple the sum of species deviances.  It calculates
     the probability of obtaining as low a deviance as observed by
     permuting the species values nitr-1 times.  the p-val is then
     calculated as (n+1)/nitr where n is the number of cases with
     values as low or lower than observed.

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

     a list wit components: 

  spcdev: a dataframe with columns species, deviance, p-value

  totdev: total table deviance

_N_o_t_e:

     Table deviance is a useful way to test the validity of clusters
     derived by other means, including cutting hierarchical cluster
     analyses of non-hierarchical approaches.  In addition, it is
     useful for identifying species of interest in the local flora.

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

     David W. Roberts droberts@montana.edu <URL:
     http://ecology.msu.montana.edu/labdsv>

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

     <URL: http://ecology.montana.msu.edu/labdsv>

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

     'duleg', 'duarm'

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

         data(bryceveg) # retrieves a vegetation data frame
         clust <- sample(1:5,nrow(bryceveg),replace=TRUE)
         tabdev(bryceveg,clust)

