from itertools import combinations as comb

def statistic(ab, a):
    sumab, suma = sum(ab), sum(a)
    return ( suma / len(a) -
             (sumab -suma) / (len(ab) - len(a)) )

def permutationTest(a, b):
    ab = a + b
    Tobs = statistic(ab, a)
    under = 0
    for count, perm in enumerate(comb(ab, len(a)), 1):
        if statistic(ab, perm) <= Tobs:
            under += 1
    return under * 100. / count

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)
print("under=%.2f%%, over=%.2f%%" % (under, 100. - under))