MACRO
permute d s results
# approximate randomization: re-assigns data to groups calculates
# and plots differences of group means
# 
# data is stacked in d subscripts are in s
#
# copyright 2005 Robert L. Raymond University of St Thomas. Free use for
# teaching and noncommercial research-retain this notice in this and derivative works
MCOLUMN d s news new1 new2  results inp
MCONSTANT  reps  ntotal  k
NOECHO
#
NOTE
NOTE How many replications ?
SET inp;
  FILE  'TERMINAL';
  NOBS 1.
LET reps = inp(1)
LET ntotal = COUNT(d)
#
DO k = 1:reps
  SAMPLE ntotal s news
  COPY d new1;
    USE news = 1.
  COPY d new2;
    USE news = 2.
  LET results(k) = MEAN(new1) - MEAN(new2)
ENDDO
HISTOGRAM results;
  TITLE 'Differences of Means'.
ECHO
ENDMACRO