<P> Intra-industry trade is difficult to measure statistically because regarding products or industries as "the same" is partly a matter of definition and classification . </P> <P> For a very simple example, it could be argued that although a BMW and a Ford are both motor cars, and although a Budweiser and a Heineken are both beers, they are really all different products . </P> <P> Various indexes of IIT have been created, including the Grubel--Lloyd index, the Balassa index, the Aquino index, the Bergstrand index and the Glesjer index . Research suggests that </P> <Ul> <Li> IIT is not simply a fiction or artifact produced by statistical classifications and definitions, but very much a reality . </Li> <Li> the share of IIT in total international trade is growing all the time, at about 4--5% a year . Thus, more and more, countries are importing the same kinds of products they are also exporting . </Li> </Ul>

Intraindustry trade is most common in the trade patterns of