change are known as variables. • The variable that is manipulated, and whose changes are supposed to produce changes on another variable, is called an independent variable (IV, stimulus, or X). – IV has levels. e.g., positive vs. neutral mood; placebo vs. control; risky vs. save, etc. • The variable whose levels depend on the levels of a prior variable is defined as a dependent variable (DV, response, or Y). 9 Sani & Todman (2006)