We propose a simple approach to assess whether a nonlinear parametric model is appropriate to depict the dose-response relationships and whether two parametric models can be applied to fit a dataset via nonparametric regression. The proposed approach can compensate for the ANOVA, which is sometimes conservative, and is very easy to implement. We illustrate the performance by analyzing experimental examples and a small simulation study.
Keywords: ANOVA; IC50; biphasic/two-phase; four/five parametric logistic models; goodness-of-fit; non-monotonic curve.