I understand that correlation can tell us the association (strength, direction) between two continuous variables. I also understand that Regression analysis can predict the behavior of the dependent variable based on the independent variable.
What I am not clear is which statistical method should we use to determine if variable A has an effect on variable B, or vice-versa?
In my study, I am interested to know if usability (independent var) has an influence on affective responses (dependent var), and also whether affective state (independent var) has an effect/influence on perceived usability (dependent variable).