def _aicc(model_results, nobs):
    """Compute the corrected Akaike Information Criterion"""
    aic = model_results.aic
    df_model = model_results.df_model + 1  # add one for constant term
    return aic + 2. * df_model * (nobs / (nobs - df_model - 1.) - 1.)
Compute the corrected Akaike Information Criterion