The net difference test deals with each row independently and compares the difference between the proportions in one pair of columns with the difference between the proportions in another pair of columns. The result is tested for significance at the selected level. The results of the test are displayed in a separate column.

For example, if the difference between the proportion of women preferring Brand A before and after testing is larger than those preferring Brand B, and the difference between those two proportions is significant at the selected level, the result is flagged as significant and the letter S is displayed in the net difference column of the row for women.

When you specify a net difference test, to specify which columns to test and where to place the result, you must also add a ntd special element to your table, immediately after the four columns you want to test. If the table is nested, this must be in the innermost nesting level.

When you specify a net difference test, to specify which columns to test and where to place the result, you must also add a net difference item to the variable. If the table is nested, this must be in the innermost nesting level.

UNICOM Intelligence Professional carries out the test on the four columns preceding the net difference item.