Keisha and Kathy are both sick with the flu. Keisha has been sick with the flu in the past and decides to wait a few days before seeking medical care. Kathy has never had the flu and seeks medical care immediately. The difference between Keisha and Kathy's reactions can be explained by

Prior experience

Explanation:

It could be inferred that prior experience played a part in both Keisha and Kathy's handling of their ailment. This disparity in the handling of the ailment could be be in that Keisha having being down with flu before and relating her experience the last time out, decided to wait, this might be what she was told by the doctor during their previous encounter. Kathy on the other hand hasn't had such experience and may be shocked and eager to get herself treated. Hence, prior experience played a role in how they both responded to managing their ailment.

answer; when one group has an extremely high score at pretest;