Problem 1) An investigator wants to determine whether self-esteem affects people's willpower when dieting. She recruits 20 female students from her college (all of whom say they are on diets) to fill out a self-esteem measure. She then divides them into high and low-self-esteem groups based on their test scores. Finally, she compares the self-reported willpower of the two groups and concludes that high self-esteem leads to more willpower.
a) How has she operationalized her independent variable?
b) How has she operationalized her dependent variable?
c) Is her study a true experiment? Give one reason why or why not.
d) Name one reason why her study might have low external validity.
e) What is one rival hypothesis that might account for the study results?
Problem 2) A second investigator is also interested in how self-esteem affects willpower when dieting. 20 students (10 male and 10 female) come to his lab, one at a time. The lab room is stocked with a variety of snack foods. When they arrive, he gives them an unsolvable logic problem to work on. After 10 minutes, he secretly flips a coin. If the coin is heads, he tells the subject that he/she is doing very well on the problem. If it is tails, he tells the subject that he/she is not doing too well so far. He then leaves the room. In his analysis, he compares the number of snacks eaten by subjects in the two groups. He concludes that self-esteem has a positive effect on willpower.
a) How has he operationalized her independent variable?
b) How has he operationalized her dependent variable?
c) Is his study a true experiment? Give one reason why or why not.
d) Name one reason why his study might have low external validity.
e) What is one rival hypothesis that might account for the study results?