COMPUTE change=Postwt-Prewt.
EXECUTE.

EXAMINE VARIABLES=change BY Treat
  /PLOT BOXPLOT HISTOGRAM
  /COMPARE GROUPS
  /STATISTICS DESCRIPTIVES
  /CINTERVAL 95
  /MISSING LISTWISE
  /NOTOTAL.


AUTORECODE VARIABLES=Treat 
  /INTO treatgrp
  /PRINT.

ONEWAY change BY treatgrp
  /MISSING ANALYSIS
  /POSTHOC=FREGW ALPHA(0.05).