NADP Data (Appendix C.3) Most of the sites in the NADP data have shown increases in their mean pH levels (that is, decreases in acidity) over the past 20 years. You wish to know which of the possible...

NADP Data (Appendix C.3) Most of the sites in the NADP data have shown increases in their mean pH levels (that is, decreases in acidity) over the past 20 years. You wish to know which of the possible contributors (chlorine, ammonium, nitrous oxides, and/or sulfates) have had changes that best explain the changes in pH. Form the changes for each variable by subtracting the 1990s value from the 2010s value (e.g., ChangepH=PH_C-PH_A). Use correlations to quickly scan for the best candidate predictor of the change in pH, and then build and check an appropriate regression model.