This paper argues that the theoretical foundations for the gravity equation are general, while the empirical performance of the gravity equation is specific to the type of goods examined. Most existing theory for the gravity equation depends on the assumption of differentiated goods. We show...

We develop a procedure to rank-order countries and commodities using dis-aggregated American imports data. We find strong evidence that both countries and commodities can be ranked, consistent with the "produce cycle" hypothesis. Countries habitually begin to export goods to the United States...

We develop a procedure to rank-order objects using censored panel data sets. We illustrate this by ranking countries and commodities using disaggregated American import data and find evidence that countries and commodities can be ranked. Countries habitually begin to export goods to the United...