Gravity models describe, and hence help predict, spatial flows of commuters, air-travelers, migrants, commodities and even messages. They are one of the oldest and most widely used of all social science models. This book presents an up-to-date, consistent and unified approach to the theory,...

Standard approaches to studying industrial agglomeration have been in terms of scalar measures of agglomeration within each industry. But such measures often fail to distinguish spatial scales of agglomeration. In a previous paper, Mori and Smith (2014) proposed a pair of quantitative measures...