Discrepancies between Purchasing Power Parities and Exchange Rates under the Law of One Price: A Puzzle (partly) Explained?

European Comparison Project data (years 1999-2008) are used for an estimation of cross-country systems (AIDS) of consumer demand functions defined over durable and non-durable tradable goods and non-tradable services. General exchange equilibrium models of inter-EU trade generate equalized relative prices of tradable goods. But domestic relative prices of services become more dispersed and can move the PPP/ER ratios away from unity. PPP/ER discrepancies may be sustained even when there are no impediments to free trade.