Torsten Hägerstrand (1916- ), Swedish geographer, born in Moheda. An emeritus professor at the University of Lund, Sweden, he is best known for his research in quantitative methodology and for his studies of the diffusion process, by which he proposes that an item (such as an idea or a disease) spreads in a given area over a period of time. This theoretical model, first applied to agricultural innovations, has also been widely used in archaeology and anthropology. Hägerstrand’s principal work, Innovation Diffusion as a Spatial Process (1953; trans. 1968), was influential in its application of statistical methods and models to solve geographical problems. His other writings include The Identification of Progress in Learning (1985).