ABSTRACT
Often in environmental data analysis we are interested in the relationship between two or more variables. For example, hydrologists often use models to predict sediment load or chemical concentration in a river or stream as a function of the flow. Air quality analysts model ozone or particulate concentration as a function of other meteorological factors such as humidity, radiation, wind speed, temperature, etc. In Chapter 3 we discussed graphs for looking at the relationships between two or more variables. In this chapter we will discuss ways to model these relationships. We will postpone discussion of the special case of looking at the relationship between a variable and how it behaves over time until Chapter 11 on Time Series Analysis.
