Example of the Cell Chisq Test
This example uses the Consumer Preferences.jmp sample data table. This table contains survey data about people’s attitudes and opinions, as well as questions concerning oral hygiene. You explore the distribution of responses to the statement “I am working on my career” across age groups.
1. Select Help > Sample Data Library and open Consumer Preferences.jmp.
2. Select Analyze > Consumer Research > Categorical.
3. Select I am working on my career and click Responses on the Simple tab.
4. Select Age Group and click X, Grouping Category.
5. Click OK.
6. Click the Categorical red triangle and select Crosstab Transposed.
7. Click the Categorical red triangle and select Cell Chisq.
Figure 3.25 Cell Chisq
Small p-values indicate that there is a significant difference between the observed cell count and the expected cell count. The p-values are colored by significance level from dark red for cells with significantly higher counts than expected to dark blue for cells with significantly lower counts than expected. The expected cell count is based on the observed row and column totals. The expected cell count is calculated as the row total times the column total divided by the overall count.
For example, the expected number of responses under the null hypothesis that the rates are equal in the 25 - 29 group who agree is (287*113)/448 = 72.4; the observed value was 95. This observed value, with a p-value of 0.00788, is significantly larger than the expected value. The number of responses in the 25 - 29 group who agree with “I am working on my career” is higher than expected if the response to this question was independent of age.