One Variable as a Function of the Other

This chapter explores ways to represent relationships between two variables a, b when the relationship can be expressed as an explicit function, that is, in the form b = f(a). We refer to a and b respectively as the independent and dependent variables. It is customary to plot the independent variable on the x-axis of the chart and the dependent one on the y-axis. The function f can be given as an algebraic expression or, more commonly, as a list of (a, b) pairs. The chapter presents two different tools for visualizing one variable as a function of the other: line charts and slope charts.