'More precise calculation, 1 - cdf doesn\'t cut it.'

def _sf(self, k, M, n, N):

    res = []
    for (quant, tot, good, draw) in zip(k, M, n, N):
        k2 = np.arange((quant + 1), (draw + 1))
        res.append(np.sum(self._pmf(k2, tot, good, draw)))
    return np.asarray(res)
