A Psychologist Suggests That,as There Is a Positive Correlation Between

Multiple Choice

A psychologist suggests that,as there is a positive correlation between people who take more vacations and better physical health,people should take more vacations to improve their physical health.After thinking about this result,you realize that this association may be a result of a third factor: income.People with more income can afford more vacations and can afford better health care.This explanation best illustrates which limitation of correlational research?

A) bidirectional causality problem
B) third variable problem
C) placebo effect
D) experimenter expectancy effects