13.54 Availability of food, amount eaten, and correlation: Did you know that sometimes you eat more just because the food is in front of you? Geier et al., (2006) studied how portion size affected the amount people consumed. They discovered interesting things such as that people eat more M&M’s when the candies are dispensed using a big spoon as compared with when a small spoon is used. They investigated whether people eat more when more food is available. Hypothetical data are presented in the table for the amount of candy presented in a bowl for customers to take and the amount of candy taken by the end of each day of the study.

Number of Pieces Presented Number of Pieces Taken 10 3 25 14 50 26 75 44 100 36 125 57 150 41

a. What are the two variables in this study? What type of variable is each?

b. Create a scatterplot of these data.

c. Describe your impression of the relation between these variables based on the scatterplot.

d. Compute the Pearson correlation coefficient for these data.

e. Summarize your findings using Cohen’s guidelines.

f. Perform the remaining steps of hypothesis testing. g. What limitations are there to the conclusions you can draw based on this correlation? h. Use the A-B-C model to explain possible causes for the relation between these variables.