*  This is file CENTER.SPS
TITLE 'Simple example of effect of centering on regression'
DATA LIST FILE=center.dat LIST
  / Y X
* Note:  the simplest way to center in SPSS is to compute the mean
*        before the analysis and input it directly in the compute step
COMPUTE Xc=X-5.5
COMPUTE X2=X**2
COMPUTE Xc2=Xc**2
VAR LABELS Y = 'Y value'
        X = 'X variable; raw'
        X2= 'squared X'
        Xc='X variable; centered'
        Xc2='squared centered X'
* Regression with raw X value, X
REGRESSION
  /variables Y X X2
  /statistics= defaults tol
  /dependent=Y
  /enter X X2
* Regression with centered X value, Xc
REGRESSION
  /variables Y Xc Xc2
  /statistics=defaults tol
  /dependent=Y
  /enter Xc Xc2
FINISH