GMACRO
Babies 

erase c4
name c4 'number of matches'

NOTE
NOTE Random Babies Simulation
NOTE
NOTE At the 'DATA>' prompt below, enter the number of times to repeat the
NOTE simulation:
NOTE

set c100;
  file "terminal";
  nobs 1.
copy c100 k1

do k2=1:k1
  sample 4 c1 c2;
    noreplace.
  let c3=(c1=c2)
  let c4(k2)=sum(c3)
enddo

tally c4;
  counts;
  percents.
  
ENDMACRO