The paper “A Cross-National Relationship Between Sugar Consumption and Major Depression?”

(Depression and Anxiety [2002]: 118–120) concluded that there was a correlation between re fined sugar consumption (calories per person per day) and annual rate of major depression (cases per 100 people) based on data from six countries. The following data were read from a graph that appeared in the paper:

Country Sugar Consumption Depression Rate Korea 150 2.3 United States 300 3.0 France 350 4.4 Germany 375 5.0 Canada 390 5.2 New Zealand 480 5.7

a. Compute and interpret the correlation coef fi cient for this data set.

b. Is it reasonable to conclude that increasing sugar consumption leads to higher rates of depression?

Explain.

c. Do you have any concerns about this study that would make you hesitant to generalize these conclusions to other countries?