Just the Essentials of Elementary Statistics
by Robert Johnson and Patricia Kuby

Chi-Square and Contingency Table Applet from Seeing Statistics

This Seeing Statistics applet displays a contingency table, its chi-square statistic, and the corresponding mosaic plot. Cells in the mosaic plot are proportional to the number of observations in that cell. The more the cell frequency is greater than expected (for the null hypothesis of no association), the more intense the blue coloring of the cell. Red coloring indicates fewer observations than expected.

When this page loads initially, the applet displays the example from Illustration 11-5, pp. 483-484 of Just the Essentials of Elementary Statistics.

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  How-To:
  • Hold mouse down on any cell in the mosaic plot to see a description of that cell's contents, inluding its proportion of the row.
  • Change cell freqencies either by typing in the boxes (row and column totals may not be changed) or by dragging the cells by the black handles (dragging is only practical on fast computers).
  • Change the total count (the lower right cell in the table) to see the effect on chi-square and the confidence of the conclusion about each cell being over or under the expected value.
  • Click on the Data/Null button to switch between viewing the data and viewing the plot as it would appear if there were no association between the two variables.
  • Click on the Reset button to restore the original data.

See another chi-square example from Just the Essentials of Elementary Statistics

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The above applet is from the chapter on "Chi-Square and Contingency Tables" from Seeing Statistics by Gary McClelland. For more information, visit Seeing Statistics

© 1999, Duxbury Press