Some correlational studies have found that people who are chronically depressed are more likely than non-depressed people to develop cancer. Which of the following can be derived from the study?
A) Chronic depression causes cancer.
B) Early, undetected cancer causes depression.
C) Depressed people tend to smoke, causing cancer.
D) Chronic depression and cancer are related to one another.

Question

Quizplus · Accepted Answer

The study found a relationship between chronic depression and the likelihood of developing cancer. However, the study cannot determine the direction of causality, so it cannot be concluded that chronic depression causes cancer or that early, undetected cancer causes depression. While depressed people may be more likely to smoke, the study did not provide evidence that smoking was the causal link between depression and cancer.

Some Correlational Studies Have Found That People Who Are Chronically