def METHOD_NAME(self):
    """Test function multivariate_ttest.
    Tested against the R package Hotelling and real-statistics.com.
    """
    np.random.seed(123)
    # With 2 variables
    mean, cov, n = [4, 6], [[1, 0.5], [0.5, 1]], 30
    Z = np.random.multivariate_normal(mean, cov, n)
    # One-sample test
    multivariate_ttest(Z, Y=None, paired=False)
    multivariate_ttest(Z, Y=[4, 5], paired=False)
    # With 3 variables
    # Two-sample independent
    stats = multivariate_ttest(X, Y)
    assert round(stats.at["hotelling", "F"], 3) == 1.327
    assert stats.at["hotelling", "df1"] == 3
    assert stats.at["hotelling", "df2"] == 32
    assert round(stats.loc["hotelling", "pval"], 3) == 0.283
    # Paired test with NaN values
    stats = multivariate_ttest(X_na, Y, paired=True)
    assert stats.at["hotelling", "df1"] == 3
    assert stats.at["hotelling", "df2"] == X.shape[0] - 1 - X.shape[1]