import numpy as np def aic_statistic(dist, data, axis): """ AIC-based goodness-of-fit statistic. AIC = 2k - 2ln(L) Lower AIC indicates better fit, but since goodness_of_fit() treats larger statistic values as worse fit, AIC works directly. """ k = len(dist.args) log_likelihood = np.sum(dist.logpdf(data), axis=axis) aic = 2 * k - 2 * log_likelihood return aic def bic_statistic(dist, data, axis): """ BIC-based goodness-of-fit statistic. BIC = ln(n)k - 2ln(L)s Lower BIC indicates better fit, but since goodness_of_fit() treats larger statistic values as worse fit, BIC works directly. """ n = data.size if axis is None else data.shape[axis] k = len(dist.args) log_likelihood = np.sum(dist.logpdf(data), axis=axis) bic = np.log(n) * k - 2 * log_likelihood return bic