Forty-nine volunteer college students were told they were going to watch a lecture on video and rate the instructor Twenty-five students were randomly selected and told that other students had rated the instructor as "charismatic": lively, stimulating, and encouraging. The other twenty-four students were told that other students had rated the instructor as “punitive": not helpful, not interested in students, and a hard grader. Then, all students watched the same twenty-minute video given by the same instructor. They then rated the instructor in that video. The students who were told that the instructor was charismatic gave higher ratings, on average, than the students who were told that the instructor was punitive. We cannot tell whether this was a well-designed experiment because: a
the number of students may have been too small
b the video may have been too short.
c all students observed the same video. d the subjects were volunteers.
e only one group was randomly assigned.