Grubel–Lloyd index

The Grubel–Lloyd index measures intra-industry trade of a particular product. It was introduced by Herb Grubel and Peter Lloyd in 1971.

G L i = ( X i + M i ) − | X i − M i | X i + M i = 1 − | X i − M i | X i + M i ;   0 ≤ G L i ≤ 1

where X_i denotes the export, M_i the import of good i.

If GL_i = 1, there is only intra-industry trade, no inter-industry trade. This means for example the Country in consideration Exports the same quantity of good i as much at it Imports. Conversely, if GL_i = 0, there is no intra-industry trade, only inter-industry trade. This would mean that the Country in consideration only either Exports or only Imports good i.