Question
Can you think of times when a one-tailed test would beappropriate? What if, after an extensive literature review,you found the differences between means to generally go in just onedirection? Would you want to perform a one-tailed test inthat situation? Why or why not? Can you think of times when a one-tailed test would beappropriate? What if, after an extensive literature review,you found the differences between means to generally go in just onedirection? Would you want to perform a one-tailed test inthat situation? Why or why not?
Explanation / Answer
Many medical situations, especially withnew medications and treatments, are times when a one-tailed testwould be appropriate. Other situations include providing additionaltraining and measuring human performance. If an extensiveliterature review shows the differences between means to generallygo in just one direction, we would you want to perform aone-tailed test in that situation, especially if a decrease seemsillogical, unreasonable, unlikely, or not of interest. If thesample mean is thought to be differentfrom the population mean in a specific direction only—itwould be better to use a directional or one-tailedtest because the region of rejectionis completely in one tail of the distribution.