Previously you have studied the Factor Effect. This looks at ratios within the data table. Now we will look at a pattern that comes from graphs.
Direct
Square
Inverse
Square Root
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This graph illustrates the pattern known as the Characteristic Plot of the dependent variable versus the control variable for the Direct Relationship. The characteristic plot for a Direct Relationship is a straight line graph. |
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This graph illustrates the Characteristic Plot found for the Inverse Relationship. The characteristic plot for an Inverse Relationship is a curve of the type illustrated here. As one of the variables increases, the other decreases. Note: It is not a straight line sloping downward. |
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This graph is Characteristic of a Square Relationship. The Characteristic Plot for a Square Relationship is a curve of the type illustrated here. The Control variable increases more rapidly than the Dependent variable does, resulting in a curve. You may recognize this as a parabola, centered around the y-axis. More on this later. |
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The graph shown here is characteristic of a Square Root relationship. The dependent variable increases less rapidly than the control variable does, leading to a graph curving over towards the right. You may recognize this as a parbola centered on the x-axis. More on this later. |
The general nature of many relationships can be determined from a simple plot of Dependent vs. Control. If the graph is a straight line, we know it is a Direct Relationship. If it has one of the curves shown above, then it could be the corresponding relationship. Further analysis is needed, however, to pin down the exact nature of the relationship.Updated August 2001