SPATIAL DIFFUSION OF SOCIAL ORGANIZING: MODELING TRADE UNION GROWTH IN SWEDEN, 1890–1940

We develop a model to analyze the growth of social organizations as a spatially nested mixed-influence diffusion process. Drawing on gravity models and threshold models, we split the social system into social units and model the diffusion process as a system of differential equations. The diffusion of a new organizational form in a social unit is a function of an internal process within the unit and external processes in the surrounding units. The model is confronted with data on the growth of trade unions in Stockholm, Sweden, between 1890 and 1940.