'Tests Gamma family with canonical inverse link (power -1)'

@classmethod
def setup_class(cls):

    cls.decimal_aic_R = (-1)
    cls.decimal_resids = DECIMAL_2
    from statsmodels.datasets.scotland import load
    from .results.results_glm import Scotvote
    data = load()
    data.exog = add_constant(data.exog, prepend=False)
    with warnings.catch_warnings():
        warnings.simplefilter('ignore')
        res1 = GLM(data.endog, data.exog, family=sm.families.Gamma()).fit()
    cls.res1 = res1
    res2 = Scotvote()
    res2.aic_R += 2
    cls.res2 = res2
