Developing countries generally are not only concerned with the level of their export earnings but also with the commodity and geographic composition of exports, and, to a lesser extent, of imports. Concern over a high degree of commo¬dity structure in exports is usually based on its presumed association with adverse price movements. A more diversified export commodity structure will reduce the impact on the overall level of foreign-exchange earnings from price fluctuations in any particular commodity. While concentration on a few commodities need not be identified with being a primary commodity exporter, for many developing countries a high degree of commodity concentration is often correlated with the exports of primary commodities [6 ; 9]. The familiar terms-of-trade argument, the belief that the relative price of primary commodity exports will fall, over the long run, as compared to the price of industrial goods imports, provides a second rationale for seeking a diversification in the composition of exports. Even in the short run the prices of most primary products in interna¬tional trade vary more sharply from year to year than those of most industrial products thus providing an additional incentive for decreasing commodity con¬centration .