testNL.RdTests for model improvements for non-linear transformations and polynomials with Clarke's (2007) distribution-free test for non-nested models.
testNL(obj, var, transPower, polyOrder, plot = FALSE, ...) # S3 method for glm testNL(obj, var, transPower, polyOrder, plot = FALSE, ...) # S3 method for lm testNL(obj, var, transPower, polyOrder, plot = FALSE, ...)
| obj | Object of a supported class in which non-linear functional forms will be tested. |
|---|---|
| var | String giving name of variable to be tested. |
| transPower | The name value of the power used in the transformation. |
| polyOrder | The order of the polynomial to be used. |
| plot | Logical indicating whether the effects should be plotted |
| ... | Currently not implemented. |
A plot or a data frame giving the results of the tests identified above.
Three hypotheses are tested with this function. The first is whether the original specification is preferred to the power transformation. The second is whether the original specification is preferred to the polynomial model. The third is whether the power transformation is preferred to the polynomial model. All tests are done with the Clarke test.
Kevin Clarke. 2007. "A Simple Distribution-Free Test for Nonnested Hypotheses." Political Analysis 15(3): 347--363.