'Inverse Cumulative Distribution (Quantile) Function
Notes
Will not work if fit has not been called. Uses
`scipy.stats.mstats.mquantiles`.'

@cache_readonly
def icdf(self):

    _checkisfit(self)
    gridsize = len(self.density)
    return stats.mstats.mquantiles(self.endog, np.linspace(0, 1, gridsize))
