Researchers who are now well known conducted the three classic studies that follow. For each study, identify the dependent variable, the independent variable, and the number and names of the levels of the independent variable. Complete items i and ii.

a. Theodore Barber hypnotized 25 different people, giving each a series of suggestions. The suggestions included arm rigidity, hallucinations, color blindness, and enhanced memory. Barber counted the number of suggestions that the hypnotized participants complied with (the mean was 4.8). For another 25 people, he simply asked them to achieve the best score they could (but no hypnosis was used). This second group was given the same suggestions, and the number complied with was counted (the mean was 5.1). (See Barber, 1976.)

i. Identify a nominal variable and a statistic.

ii. In a sentence, describe what Barber’s study shows.

b. Elizabeth Loftus had participants view a film clip of a car accident. Afterward, some were asked, How fast was the car going? and others were asked, How fast was the car going when it passed the barn? (There was no barn in the film.) A week later, Loftus asked the participants, Did you see a barn? If the barn had been mentioned earlier, 17 percent said yes; if it had not been mentioned, 3 percent said yes. (See Loftus, 1979.)

i. Identify a population and a parameter.

ii. In a sentence, describe what Loftus’s study shows.

c. Stanley Schachter and Larry Gross gathered data from obese male students for about an hour in the afternoon. At the end of this time, a clock on the wall was correct (5:30 p.m.) for 20 participants, slow (5:00 p.m.) for 20 others, and fast (6:00 p.m.) for 20 more. The actual time, 5:30, was the usual dinnertime for these students. While participants filled out a final questionnaire, Wheat Thins® were freely available. The weight of the crackers each student consumed was measured. The means were: 5:00 group—20 grams; 5:30 group—30 grams; 6:00 group—40 grams. (See Schachter and Gross, 1968.)

i. Identify a ratio scale variable.

ii. In a sentence, describe what this study shows.