price ggplot (diamonds, aes (x-carat, y-price, color-clarity)) + geom_point () +geom_smooth() 20000- 15000- 10000- 5000- 0- carat clarity = VVS2 VVS1 Do any of these plots suggest a non-linear (e.g., quadratic or cubic) function in carat? g. In the model selected by stepwise selection you have interaction between carat and several other variables. Change the linear effect of carat to a polynomial and select the degree of the polynomial by cross validation. What degree do you select? You can recycle most of the CV code from the Chapter 4 section 4.1-4.3 exercises, but replace the call to glm() fit with one that includes the all the models terms of interest: fit