Analysis of Contingency Tables

This applet will allow you to vary the cell entries in a contingency table and computes chi-square and its associated probability value. It also shows the contribution of each cell by varying the brightness of the cell colors.

The applet is shown below, where the data are taken from Table 9.2, which relates to the Darley and Latane study of helping behavior as a function of the number of bystanders.

Enter the appropriate values in the cells. Blue cells represent higher than expected numbers of observations, while pink cells represent fewer observations than expected. The brighter the colors, the greater the difference from expected.

Enter the data from Pugh's experiment on convictions for rape.
Enter the data from Latane and Dabbs in Section 19.6.
For the Latane and Dabbs study, where could you add 10 observations to make the most difference in chi-square?
If you double the total sample size without making changes to any of the cells, the applet will automatically double those entries. Do this and observe the changes in chi-square and the color of the cells.

What does the last item say about power and sample size?
What if you just sampled twice as many observations in one of the rows?

Comments to: Gary.McClelland@Colorado.e du

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