Hannah wants to see if her new technique of ping-pong playing can increase one's ping-pong performance. She asks the U. S. Olympic ping-pong team to work with her. Half of the U. S Olympic team is randomly assigned to be taught by the new style, the experimental group, and the other randomly assigned half are not, the control group. Her technique does not significantly increase the performance of the experimental group compared to the control group, perhaps because they are already so good at the sport. This could be an example of Group of answer choices the need for matching groups. a ceiling effect. the need for determining initial comparability. an internally invalid study.