Method: Statsample::Test::UMannWhitney.distribution_permutations

Defined in:
lib/statsample/test/umannwhitney.rb

.distribution_permutations(n1, n2) ⇒ Object

Generate distribution for permutations. Very expensive, but useful for demostrations



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# File 'lib/statsample/test/umannwhitney.rb', line 78

def self.distribution_permutations(n1,n2)
  base=[0]*n1+[1]*n2
  po=Statsample::Permutation.new(base)
  
  total=n1*n2
  req={}
  po.each do |perm|
    r0,s0=0,0
    perm.each_index {|c_i|
      if perm[c_i]==0
        r0+=c_i+1
        s0+=1
      end
    }
    u1=r0-((s0*(s0+1)).quo(2))
    u2=total-u1
    temp_u= (u1 <= u2) ? u1 : u2
    req[perm]=temp_u
  end
  req
end