Correlation - variables?

Question

When calculating the correlation between two variables, do we have a dependent and independent variable, or are they both the same?

Answer 1

Sometimes we do have a dependent and independent variable, sometimes it doesn't matter. It depends on the context.

For example, when examining the correlation between the following 2 sets of data:

(a)the number of answers in a yahoo! question, and the points awarded by the person asking the question. In this case, it makes sense to specify the amount of points as the independent variable and the number answers received as dependent variable. (Obviously the correlation is positive)

(b)Correlation between height and weight. In this case, it doesn't matter which one is the independent variable and which one is the dependent variable.