Migrant and ethnic diversity, cities and innovation: Firm effects or city effects?

The growing cultural diversity caused by immigration 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 help firms innovate. This article uses a dataset of over 2000 UK small-and medium-sized enterprises to test between these two. Controlling for firm characteristics, city characteristics and firm and city diversity, there is strong evidence for the firm effect. Firms with a greater share of migrant owners or partners are more likely to introduce new products and processes. This effect has diminishing returns, suggesting that it is a 'diversity' effect rather than simply the benefits of migrant run firms. However, there is no relationship between the share of foreign workers in a local labour market or fractionalization by country of birth and firm level innovation, nor do migrant-run firms in diverse cities appear particularly innovative. But urban context does matter and firms in London with more migrant owners and partners are more innovative than others. Firms in cities with high levels of human capital are also more innovative.