Two simulation studies are reported in Section 5. The first study illustrates the implementation and usefulness of our method for a cubic model. The second study uses the simple quadratic model where the efficiency and accuracy of the new general procedure can be compared to the existing methods. Section 6 discusses an example from a substance abuse intervention study where the theory suggests the inadequacy of a quadratic relationship, and where the approach proposed in this paper is successfully applied to compare quadratic, cubic, and quartic models. A brief summary is given in Section 7.
Appendix covers some details.