def METHOD_NAME(self):
    # Tests that ESS for a single parameter is correct
    # For case with negative elements in x
    x = np.array([1, 2, 3, 4, -1, -1])
    y = pints._diagnostics.effective_sample_size_single_parameter(x)
    self.assertAlmostEqual(y, 1.75076, 5)
    # Case with positive elements only in x
    x = np.array([1, 2, 3, 4, 1, 1])
    self.assertAlmostEqual(
        pints._diagnostics.effective_sample_size_single_parameter(x),
        1.846154, 6)