Graphs and Graphing

The scatter graph is similar to the bar graph in that it is used to represent relations containing a small number of ordered pairs. However, it differs from the bar graph in that both axes can be used to represent sets of real numbers. Since it is not feasible to represent pairs of real numbers with bars that have some width, ordered pairs of the relation are plotted by marking the corresponding point with a small symbol, such as a circle, or square. Since the scatter graph represents relations between sets of real numbers, it may also include negative as well as positive numbers. In producing a scatter graph, the location of each point is established by its horizontal distance from the y-axis and its vertical distance from the x-axis. Scatter graphs are used extensively in picturing the results of experiments. Data is generated by controlling one variable (called the independent variable) and measuring the response of a second variable (called the dependent variable). The data is recorded and then plotted, the independent variable being associated with the x-axis and the dependent variable with the y-axis.