We note that the existence of the maximum likelihood estimates for Poisson regression depends on the data configuration. Because standard software does not check for this problem, the practitioner may be surprised to find that in some applications estimation of the Poisson regression is...

We extend the simulation results given in Santos-Silva and Tenreyro (2006, ‘The Log of Gravity’, The Review of Economics and Statistics, 88, pp.641-658) by considering data generated as a finite mixture of gamma variates. Data generated in this way can naturally have a large proportion of...

This paper examines the frequency, pervasiveness, and determinants of product switching by US manufacturing firms. We find that one-half of firms alter their mix of five-digit SIC products every five years, that product switching is correlated with both firm- and firm-product attributes, and...

London is one of the world’s major cities, and one of its most diverse. London’s cultural diversity is widely seen as a social asset, but there is little hard evidence on its importance for the city’s businesses. Theory and evidence suggest various links between urban cultural diversity...

Globalization and the ICT revolution of the 1990s have forced many firms to reorganize in order to survive in a more competitive market. There are several approaches that can be used to assess the measurement of organization capital since it is unobservable. Using an optimizing firm model and...

We estimate a structural model of heterogeneous multiproduct firms to examine the sources of firm heterogeneity emphasized in the recent trade and macro literatures. Using Nielsen barcode data on prices and sales, we estimate elasticities of substitution within and between firms, and use the...

We explain a counterintuitive empirical finding: Firms facing more import competition do more innovation. In our model, factors are trapped inside a firm. An increase in import competition encourages a firm to innovate by reducing the opportunity cost of inputs. Without trapped factors, trade...

Growing cultural diversity is seen as important for innovation. Research has focused on two potential mechanisms: a firm effect, with diversity at the firm level improving knowledge sourcing or ideas generation, and a city effect, where diverse cities helping firms innovate. This paper uses a...