Foundations of Economics, 8th Edition

Appendix: Making and Using Graphs

When you have completed your study of this appendix, you will be able to

1. 1 Interpret graphs that display data.

2. 2 Interpret the graphs used in economic models.

3. 3 Define and calculate slope.

4. 4 Graph relationships among more than two variables.

Basic Idea

A graph represents a quantity as a distance and enables us to visualize the rela­tionship between two variables. To make a graph, we set two lines called axes perpendicular to each other, like those in Figure A1.1. The vertical line is called the y-axis, and the horizontal line is called the x-axis. The common zero point is called the origin. In Figure A1.1, the x-axis measures temperature in degrees Fahrenheit. A movement to the right shows an increase ...