MACRO
permute2 d1 d2 results
#
# approximate randomization for difference of two means when
# data is in columns d1 and d2
# 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 d1 d2 results joined subs
MCONSTANT nu1 nu2
NOECHO
#
LET nu1 = COUNT(d1)
LET nu2 = COUNT(d2)
STACK d1 d2 joined
SET subs
nu1(1)  
nu2(2)
END
# now subs contains nu1 ones followed by nu2 twos
NOTE  ...macro is running ...
CALL permute joined subs results
ECHO
ENDMACRO

MACRO
permute d s results
#
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