The level of uncertainty will depend on several factors: the nature of the functional form used in the multivariate analysis; the type of econometric technique employed; the appropriateness of the statistical assumptions embedded in the model or technique; the comprehensiveness of the variables included in the analysis; and the accuracy of the data that are utilized. [...] We have calculated the average production-run length of a plant as the ratio of the plant output to the number of products produced by the plant. [...] The result was an increase during the 1990s in both the export intensity and the import intensity of the Canadian manufacturing sector. [...] On the one hand, tariff cuts increase the plant size of exporters by increasing the production-run length of the portion of the product line that is exported. [...] When choosing its product range and the length of production runs, a firm no longer neglects its impact on the market as in monopolistic competition models of trade.2 The firm must account for the impact of its choice on the demand for its varieties through its effect on total market demand Q, which is the sum of the demand for the varieties of firm i. and those of its competitors (Q−i ). These di