Patent data have been widely used in research on technological innovation to characterize firms' locations as well as the proximities among firms in knowledge space. Researchers could measure proximity among firms with a variety of measures based on patent class data, including Euclidean...

Patent data have been widely used in research to characterize firms' locations in technological or knowledge space, as well as the proximities among firms. Researchers have measured firms' technological or knowledge proximities with a variety of measures based on patent data, including Euclidean...