Basic Analysis and Graphing - SAS

Chapter 6 Performing Contingency Analysis 189
Mosaic Plot
Exact Test
Provides exact versions of the following tests:
• Fisher’s Test
• Cochran Armitage Trend Test
• Agreement Test
See “Exact Test” on page 200.
Mosaic Plot
The mosaic plot is a graphical representation of the two-way frequency table or Contingency Table. A
mosaic plot is divided into rectangles, so that the area of each rectangle is proportional to the proportions of
the Y variable in each level of the X variable. The mosaic plot was introduced by Hartigan and Kleiner in
1981 and refined by Friendly (1994).
To produce the plot shown in Figure 6.5, follow the instructions in “Example of Contingency Analysis” on
page 185.
Figure 6.5 Example of a Mosaic Plot
Note the following about the mosaic plot in Figure 6.5:
• The proportions on the x-axis represent the number of observations for each level of the X variable,
which is country.
• The proportions on the y-axis at right represent the overall proportions of Small, Medium, and Large
cars for the combined levels (American, European, and Japanese).
• The scale of the y-axis at left shows the response probability, with the whole axis being a probability of
one (representing the total sample).
Clicking on a rectangle in the mosaic plot highlights the selection and highlights the corresponding data in
the associated data table.