def _credible_interval(pmf, percentage): """ Computes a credible interval for a given distribution. If percentage=90, computes the 90% CI. Args: pmf: Pmf object representing a posterior distribution percentage: float between 0 and 100 Returns: sequence of two floats, low and high """ cdf = _13_Cdf._make_cdf_from_dict(pmf._get_dict()) prob = (1 - percentage / 100.0) / 2 interval = [cdf._value(p) for p in [prob, 1 - prob]] return interval