Endogenous Horizontal and Vertical Differentiation: Measuring Value Added in Intra-industry Trade

The development of research studies concerning the emergence of intra-industry trade is fruitful interaction between theoretical explanations and empirical methods to measure this phenomenon. The foundation of indicators to measure the intensity of intra-industry trading caused the rise of theoretical models explaining the determinants of these trade flows. It also contributed to the debate on the need to distinguish, in empirical analyses, intra-industry trade in horizontal differentiation from that in vertical differentiation. From the beginning of the 1980s, the first theoretical analysis of intra-industry trade showed that the determinants and consequences of this type of trade are different, depending on whether the traded products differ in quality. When the products are subject to intra-industry trade between two countries with distinct qualities, this trade is vertically differentiated. Otherwise, it is called horizontal differentiation. There is a method for distinguishing intra-industry trade between two countries in vertical differentiation from those in horizontal differentiation. This method compares exports' unit value to imports for each industry's intra-industry trade. It considers the intra-industry trading carried out in this industry as vertical differentiation when the unit value of exports differs significantly from that of imports. This approach has limitations. This discussion will lead us to think about an alternative method for separating and measuring intra-industry trade into horizontal and vertical differentiation.