/*
--------------------------------------------------------------------------------
  program:   tetra2.sas
  purpose:   This SAS program demonstrates factor analysis of 
             tetrachoric correlation coefficients.

             Here the tetrachoric correlation matrix dataset
             produced by the previous program, tetra1.sas,
             is supplied to PROC FACTOR.

             A 1-commmon factor model is requested, using
             unweighted least-squares estimation. 

             Note:  ordinarily, the code from both these
             programs (tetra1.sas, tetra2.sas) would be
             placed in a single sas program file.

 written:    14 august 2006
--------------------------------------------------------------------------------
*/

options nocenter nodate pageno=1;

title  'Factor Analysis of Tetrachoric Correlation Coefficients';
title2 'LSAT6 Data (Bock & Lieberman, 1970)';
title3  '1-Common Factor Model - ULS Estimation';

* ---------------------- ;
* Do the factor analysis ;
* ---------------------- ;

proc factor
   data   = one
   method = uls
   n      = 1
   nobs = 1000
   ;
run;

/* 
----------------------------------------------------------------------
   Notes:  Other generally useful options are
   
      scree      (produce scree plot of eigenvalues)
      rotate = v (varimax rotation)
      reorder    (list variables by strength of loading per factor)
----------------------------------------------------------------------
*/