The issue of measuring product variety has received relatively little attention due to its inherent difficulty. In the language of index numbers, an expansion in the range of inputs or outputs is a 'new goods' problem: a good that is newly available will have an observed price and quantity, but...

Three sources of gains from trade under monopolistic competition are: (i) new import varieties available to consumers; (ii) enhanced efficiency as more productive firms begin exporting and less productive firms exit; (iii) reduced markups charged by firms due to import competition. The first...