@staticmethod
    def _norm_cum_pdf(z):
        return 0.5 - 0.5 * math.erf(z / math.sqrt(2))
:return: a data frame with names and distinct counts and fractions for all columns in the database
dataset/ETHPy150Open aalto-speech/morfessor/morfessor/evaluation.py/WilcoxonSignedRank._norm_cum_pdf--crossover with--dataset/ETHPy150Open grundprinzip/pyxplorer/pyxplorer/manager.py/Database.dcounts