#import data yang digunakan ke Stata
import excel "C:\Users\ACER\Downloads\Jurnal Parameter\VEP_Lebong.xlsx", sheet("Sheet1") firstrow

#Korelasi Tetrachoric
tetrachoric r2001a r2001b r2001f r2001g r2001h r2001k r2001l r2001m
(obs=549)

             |   r2001a   r2001b   r2001f   r2001g   r2001h   r2001k   r2001l   r2001m
-------------+------------------------------------------------------------------------
      r2001a |   1.0000 
      r2001b |   0.5532   1.0000 
      r2001f |   0.7574   0.6529   1.0000 
      r2001g |   0.4337   0.6447   0.5817   1.0000 
      r2001h |   0.3382   0.5367   0.6384   0.2777   1.0000 
      r2001k |   0.7580   0.6281   0.7535   0.6261   0.3870   1.0000 
      r2001l |   0.7158   0.6628   0.6877   0.5571   0.3635   0.7329   1.0000 
      r2001m |   0.2830   0.2264   0.1412   0.1955   0.1518   0.0310   0.2112   1.0000 

. matrix K=r(Rho)

#Analisis Komponen utama
pcamat K, n(549) comp(1)
Principal components/correlation                 Number of obs    =        549
                                                 Number of comp.  =          1
                                                 Trace            =          8
    Rotation: (unrotated = principal)            Rho              =     0.5784

    --------------------------------------------------------------------------
       Component |   Eigenvalue   Difference         Proportion   Cumulative
    -------------+------------------------------------------------------------
           Comp1 |      4.62699      3.62896             0.5784       0.5784
           Comp2 |      .998036      .166446             0.1248       0.7031
           Comp3 |       .83159      .179517             0.1039       0.8071
           Comp4 |      .652073        .2996             0.0815       0.8886
           Comp5 |      .352473      .107214             0.0441       0.9326
           Comp6 |      .245259     .0603222             0.0307       0.9633
           Comp7 |      .184937     .0763007             0.0231       0.9864
           Comp8 |      .108636            .             0.0136       1.0000
    --------------------------------------------------------------------------

Principal components (eigenvectors) 

    --------------------------------------
        Variable |    Comp1 | Unexplained 
    -------------+----------+-------------
          r2001a |   0.3849 |       .3145 
          r2001b |   0.3857 |       .3117 
          r2001f |   0.4173 |       .1943 
          r2001g |   0.3401 |       .4649 
          r2001h |   0.2804 |       .6363 
          r2001k |   0.4034 |        .247 
          r2001l |   0.3948 |       .2788 
          r2001m |   0.1269 |       .9255 
    --------------------------------------

#uji kelayakan komponen yang terbentuk
factortest r2001a r2001b r2001f r2001g r2001h r2001k r2001l r2001m

Determinant of the correlation matrix
Det                =     0.251
 
 
Bartlett test of sphericity
    
Chi-square         =           752.278
Degrees of freedom =                28
p-value            =             0.000
H0: variables are not intercorrelated
 
 
Kaiser-Meyer-Olkin Measure of Sampling Adequacy
KMO               =     0.808
 

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