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The paired preference test compares pairs of values to see whether the figures in each pair differ significantly from each other. The paired preference item is usually specified in a row. However, you can specify it in a column. The test works as follows:
• If specified in a row, the paired preference test deals with each column independently and compares pairs of rows. The test needs a minimum of two rows to be able to compare their figures.
• If specified in a column, the paired preference test deals with each row independently and compares pairs of columns. The test needs a minimum of two columns to be able to compare their figures.
For example, if the proportion of women preferring Brand A is larger than those preferring Brand B, and the difference between the two proportions is significant at the selected level, the letter S is displayed in the paired preference row of the column for women.
To specify which rows to test and where to place the result, you need to add a paired preference item to the row or column. See the topic Adding a Paired Preference Test or a Net Difference Test for more information.
When a paired preference element is placed in a row or column, IBM® SPSS® Data Collection Survey Reporter searches for the nearest two categories preceding the paired preference item, and carries out the paired preference test on those two categories. For the purposes of the paired preference test the following element types are classed as "category" elements:
• category
• expression
• net
• combine
• numeric
The result of the test is placed at the position of the paired preference row or column.
The following information assumes specification as a column.
The null hypothesis is that the two figures being compared are equal, that is, the difference between them is zero. The following table shows the symbols that are displayed on the table for different results.
| Result | Displayed |
|---|---|
| Significant at the selected level | S |
| Significant at the lower selected level but not the higher level | s |
| Not significant at the selected level(s), but significant at the 32% level | NS |
| Not significant at the 32% level | E |
That is:
• If the result of the test is significant at the specified significance level, Survey Reporter places the letter S in the additional column.
• If you run the test at two significance levels, results that are significant at the higher level are displayed using an uppercase S, and results that are significant at the lower level are displayed using a lowercase s.
• If the result of the test is not significant at the selected level(s), but is significant at the 32% significance level (equivalent to a p value of 0.32 or a confidence level of 68%, indicating that the difference between the figures being compared is at least one standard deviation away from zero) Survey Reporter places the letters NS in the additional column.
• If the difference between the figures being compared is not significant at the 32% significance level (that is, the difference is less than one standard deviation away from zero) Survey Reporter places the letter E in the additional column.