Knowledge externalities - i.e. intellectual gains made by exchange of information for which no direct compensation is given to the producer of the knowledge - result in higher economic growth rates across urban areas, as well as higher degrees of innovation intensity in those locations where economic activity is dense. By combining theories and methodologies on localised growth and innovation density from the fields of geography and economics, he puts forward an innovative spatial econometric model which contributes to a clearer understanding of actual processes of growth and innovation and...