schmid                 package:psych                 R Documentation

_A_p_p_l_y _t_h_e _S_c_h_m_i_d _L_e_i_m_a_n _t_r_a_n_s_f_o_r_m_a_t_i_o_n _t_o _a _c_o_r_r_e_l_a_t_i_o_n _m_a_t_r_i_x

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

     One way to find omega is to do a factor analysis of the original
     data set, rotate the factors obliquely, do a Schmid Leiman
     transformation, and then find omega. Here is the code for Schmid
     Leiman.  The S-L transform takes a factor or PC solution,
     transforms it to an oblique solution, factors the oblique solution
     to find a higher order (g ) factor, and then residualizes g out of
     the the group factors.

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

     schmid(model, nfactors = 3, pc = "pa",digits=NULL,...)

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

   model: A correlation matrix 

nfactors: Number of factors to extract 

      pc: pc="pa" for principal axes, pc="pc" for principal components,
          pc="mle" for maximum likelihood 

  digits: if digits not equal NULL, rounds to digits

     ...: Allows additional parameters to be passed to the factoring
          routines

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

     Schmid Leiman orthogonalizations are typical in the ability
     domain, but are not seen as often in the non-cognitive personality
     domain.  S-L is one way of finding the loadings of items on the
     general factor for estimating omega. 

     A typical example would be in the study of anxiety and depression.
      A general neuroticism factor (g) accounts for much of the
     variance, but smaller group factors of tense anxiety, panic
     disorder, depression, etc. also need to be considerd.

     An alternative model is to consider hierarchical cluster analysis
     techniques such as 'ICLUST'.

     Requires the GPArotation package.

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

     sl : loadings on g + nfactors group factors, communalities,
          uniqueness

 orthog : original orthogonal factor loadings

 oblique: oblique factor loadings

   fcor : correlations among the transformed factors

  gload : loadings of the lower order factors on g

     ...

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

     William Revelle

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

     <URL: http://personality-project.org/r/r.omega.html> gives an
     example taken from Jensen and Weng, 1994 of a S-L transformation.

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

     'omega', 'omega.graph', 'fa.graph', 'ICLUST','VSS'

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

     s.jen <- schmid(make.hierarchical(),digits=2)  #create a hierarchical demo
     s.jen

