Chapter 3.5, Problem 19AYU

Retain Your Knowledge: Decision Making and Hunger Does hunger improve strategic decision making? That is, if you are hungry are you more likely to make a favorable decision when the outcome of your decision is uncertain (as in business decisions)? To test this theory, researchers randomly divided 30 normal weight individuals into two groups. All subjects were asked to refrain from eating or drinking (except water) from 11 p.m. on the day prior to their 9 a.m. meeting. At 9 am, the subjects were randomly assigned to one of two groups. The subjects in Group 1 were fed breakfast while the subjects in Group 2 were not fed. All subjects were administered a computerized version of an exam that assesses complex decision making under uncertain conditions. The assessment consisted of subjects choosing cards from four decks marked A, B, C, and D. Cards in decks A and B had a point value of 100 while cards in decks C and D had point values of 50. However, deck A had penalty cards that deducted points between 150 and 300; deck B had one penalty card of 1250; deck C had penalty cards between 25 and 75 points; deck D had a single penalty card of 250 points. So, decks A and B had stiffer penalties over the long haul than decks C and D and in the long haul, decks C and D resulted in more points than decks A and B. In total, the subjects would select 100 cards. However, the response variable was the number of cards selected from decks C and D out of the last 60 cards selected. The thinking here is that after 40 card selections, the subjects would be aware of the advantage of decks C and D. The researchers administered a Barret Impulsivity Scale to be sure the two groups did not differ in terms of impulsivity (e.g., “I do things without thinking.”). There was no difference in impulsivity, age, or body mass index between the two groups. Before the exam, subjects were asked to report their level of hunger and it was found that Group 2 was significantly more hungry than Group 1. After analysis of the data, it was determined that the mean number of advantageous cards (decks C and D) selected by the subjects in Group 2 was 33.36 cards while the mean was 25.86 for the subjects in Group 1. The researchers concluded that hunger improves advantageous decision making.

Source:: de Ridder, D., Kroese F., Adriaanse, M., & Evers, C., “Always Gamble on an Empty Stomach: Hunger is Associated with Advantageous Decision Making.” PLOS One 9(10). doi 10.1371/journal.pone.0111081.

1. a. What type of experimental design is this?
2. b. Identify the experimental units.
3. c. What is the response variable? Is it qualitative or quantitative? If quantitative, is it discrete or continuous?
4. d. What factors that might impact the response variable are cited in the article? Which factor is manipulated? How many levels are there for the manipulated factor?
5. e. What role does randomization play in the study? How do the researchers verify that randomization resulted in similar groups prior to the treatment?
6. f. What are the statistics in the study?
7. g. What is the conclusion of the study?