Data commit

Task/Permutation-test/Ruby/permutation-test.rb

@@ -0,0 +1,20 @@
+def statistic(ab, a)
+  sumab, suma = ab.inject(:+).to_f, a.inject(:+).to_f
+  suma / a.size - (sumab - suma) / (ab.size - a.size)
+end
+
+def permutationTest(a, b)
+  ab = a + b
+  tobs = statistic(ab, a)
+  under = count = 0
+  ab.combination(a.size) do |perm|
+    under += 1 if statistic(ab, perm) <= tobs
+    count += 1
+  end
+  under * 100.0 / count
+end
+
+treatmentGroup = [85, 88, 75, 66, 25, 29, 83, 39, 97]
+controlGroup   = [68, 41, 10, 49, 16, 65, 32, 92, 28, 98]
+under = permutationTest(treatmentGroup, controlGroup)
+puts "under=%.2f%%, over=%.2f%%" % [under, 100 - under]