Purchasing power parity (PPP) is one of the most fundamental theories in international economics. However, its empirical validity is still controversial, an issue referred to in the literature as the purchasing power parity puzzle. This paper summarizes the different explanations for the empirical failures of the PPP, and proposes steps for improvements in the theory by focusing on the importance of using appropriate empirical methodology when confirming or rejecting the PPP hypothesis.

Journal of Economic Literature (JEL) codes: F31, F41