This book we believe opens a new door for a different understanding of one of the most contentious theories in open economy macroeconomics the Purchasing Power Parity. This work as far as we are concerned is the first study which adds space into the relationship between the nominal exchange rates and relative price ratios. Due to the recent advances in spatial econometrics researchers working in different fields of economics and finance have acquired an enhanced intelligence in respect of the modelling of interdependence which may better account for the genuine relationships among the variables or countries. Our study we reckon thanks to its empirical originality would be a guide for open economy macroeconomics and international finance scholars to discover novel dimensions in the areas they are currently studying.