## 9.2 The cusp package in R

Use this tutorial paper to fit the cusp in ‘R’ according to a maximum likelihood criterion.

Grasman, R. P. P. P., Van der Maas, H. L. J., & Wagenmakers, E. (2007). Fitting the Cusp Catastrophe in R: A cusp-Package.

1. Start R and install package cusp

2. Work through the Example I (attitude data) in the paper (Section 4: Examples, p. 12).

3. Example II in the same section is also interesting, but is based on simulated data.
• Try to think of an application to psychological / behavioural science.