Placement of variables in a correlation?

Question

Lung cancer correlates with smoking.Smoking correlates with lung cancer.Are both correct or does one have to worry about which one is the dependent variable (lung cancer) and which one is the independent variable (smoking)?

Answer 1

With concept sentences like this, I work both possibilities through in my mind. Lung cancer correlates with smoking means that lung cancer goes together with smoking. Smoking correlates with lung cancer means that smoking goes together with lung cancer. These are saying the same thing. Also, you could replace the phrase "lung cancer" and the word "smoking" with the general phrases "independent variable" and "dependent variable," and it still works both ways. For instance, "The independent variable correlates with the dependent variable." This has to work in the reverse: "The dependent variable correlates with the independent variable." None of these sentences is one of exclusivity (i.e. smoking is the only cause of lung cancer, or lung cancer is the only result of smoking). Because you're not writing a cause/effect sentence here ("Smoking leads to" or "Lung cancer is a result of"), the order doesn't matter logically.