When the direction (and not the magnitude) of the difference within each matched paired in a paired experiment is known, the sign test can be used while the Wilcoxon Signed-Rank test cannot be used.

Question

Quizplus · Accepted Answer

The sign test only considers the signs of the differences, while the Wilcoxon Signed-Rank test considers both the direction and magnitude of the differences. Therefore, if only the direction (sign) of the differences is known, the sign test can still be used, but the Wilcoxon Signed-Rank test cannot be used.

When the Direction (And Not the Magnitude) of the Difference