gamm4.test is a package supplied with R for testing nonlinear curve and surface functions.The main testing routine is gam.test.

The major advantages of this packages are:

Arguements formulated are consistent with semiparametric regression estimating package “mgcv” and “gamm4”, so that people who are familiar with these ones can easily adopt our major function

`gam.grptest()`

.We allow parallel computing by specifying

`parallel = TRUE`

within function`gam.grptest`

to save computational time if needed.`plot.gamtest()`

function plots semiparametric estimated nonlinear curves and surfaces via R package “plotly”. Option`type=plotly.persp`

provides a 3-D interactive plot with estimated regression functions for individual groups. Also,`test.statistic = TRUE`

provides the empirical distribution of the test statistic under the null hypothesis of equal regression function.