Golfinopoulos and Arhonditsis (A-14) used a multiple regression model in a study of trihalomethanes

(THMs) in drinking water in Athens, Greece. THMs are of concern since they have been related to cancer and reproductive outcomes. The researchers found the following regression model useful in predicting THM:
THM ¼
:26chla þ 1:57 pH þ 28:74Br
66:72Br2
43:63S þ 1:13Sp þ 2:62T  S
:72T  CL The variables were as follows: chla ¼ chlorophyll concentration, pH ¼ acid=base scale, Br ¼ bromide concentration, S ¼ dummy variable for summer, Sp ¼ dummy variable for spring, T ¼ Temperature, and CL ¼ chlorine concentration. The researchers reported R ¼ :52, p < :001.