Before revision:  Our model implies that the return to the accumulation of new capabilities increases exponentially with the number of capabilities that a country has and that this convexity increases when either the total number of capabilities that exist in the world increases or the average complexity of products (the number of capabilities they require) increases. This defines a "quiescence trap" in which countries with few capabilities have negligible returns to the accumulation of new capabilities , while countrieswith many capabilities experience large returns to the accumulation of additional capabilities . We calibrate the model to three different sets and show that it reproduces the empirically observed distributions. We conclude that in our world the quiescence trap is strong .
After revision:  Our model implies that the return to the accumulation of new capabilities increases exponentially with the number of capabilities that a country has a capability and that a product requires a capability are constant and calibrate it to the data to find that it accounts well for all of the network features except for the heterogeneity in the distribution of country diversification. In the light of the model, this is evidence of a large heterogeneity in the distribution of capabilities across countries. Finally, we show that the model implies that the increase in diversification that is expected from the accumulation of a small number of capabilities is small for countries that have a few of them and large for those with many. This implies that the forces that help drive divergence in product diversity increase with the complexity of the global economy when capabilities travel poorly .