def METHOD_NAME():
    R = _create_data_univariate()
    for p in range(1, 4):
        phi = autoregression.estimate_ar_params_ols(R[-(p + 1) :], p)
        assert len(phi) == p + 1
        for i in range(len(phi)):
            assert np.isscalar(phi[i])
        phi = autoregression.estimate_ar_params_ols(
            R[-(p + 1) :], p, include_constant_term=True
        )
        assert len(phi) == p + 2
        for i in range(len(phi)):
            assert np.isscalar(phi[i])
        phi = autoregression.estimate_ar_params_ols(
            R[-(p + 2) :], p, include_constant_term=True, d=1
        )
        assert len(phi) == p + 3
        for i in range(len(phi)):
            assert np.isscalar(phi[i])