Lakes Data (Appendix C.1) Your goal is to model summertime chlorophyll (CHL) levels as a function of levels of nitrogen and phosphorous (TN and TP). You will most likely need a transformation of all...

Lakes Data (Appendix C.1) Your goal is to model summertime chlorophyll (CHL) levels as a function of levels of nitrogen and phosphorous (TN and TP). You will most likely need a transformation of all these values and may need to construct a polynomial model. You may also need an “interaction,” that is, a variable formed by multiplying TN and TP (or multiplying their logarithms, if those are the transformations you select). A reasonable procedure is to begin with a regression using TN and TP, then find transformations of TN, TP, and CHL that produce a reasonably good starting model. After that, go on to develop polynomial or interaction terms to further improve the model. Define “summer” as months 6 through 9.