Re: st: How to implement Discrete Principal Component Analysis by using POLYCHORICPCA

[汪哲仁 <chejen.wang@gmail.com>]

Dear Cam,

Thanks for your reply. Usually, pca procedure give us a
result like this.
=================================================================================
pca foreign rep78 mpg

Principal components/correlation                  Number of obs    =        69
                                                 Number of comp.  =         3
                                                 Trace            =         3
   Rotation: (unrotated = principal)             Rho              =    1.0000

   --------------------------------------------------------------------------
      Component |   Eigenvalue   Difference         Proportion   Cumulative
   -------------+------------------------------------------------------------
          Comp1 |       1.9703      1.34377             0.6568       0.6568
          Comp2 |      .626528      .223359             0.2088       0.8656
          Comp3 |      .403169            .             0.1344       1.0000
   --------------------------------------------------------------------------

Principal components (eigenvectors)

   ----------------------------------------------------------
       Variable |    Comp1     Comp2     Comp3 | Unexplained
   -------------+------------------------------+-------------
        foreign |   0.6084   -0.2732   -0.7451 |           0
          rep78 |   0.5910   -0.4706    0.6551 |           0
            mpg |   0.5296 0.8390    0.1249 |           0
   ----------------------------------------------------------

===================================================================================
but polychoricpca only give us results without eigenvectores, like below.
polychoricpca foreign mpg rep78

 k  |  Eigenvalues  |  Proportion explained  |  Cum. explained
----+---------------+------------------------+------------------
 1 |    2.206757   |    0.735586            |   0.735586
 2 |    0.615445   |    0.205148            |   0.940734
 3 |    0.177798   |    0.059266            |   1.000000


My question is that, after running polychoricpca procedure, how can I
know the eigenvectors to construct an index.


Thanks for your attention.



with kind regards,


Charles Wang
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