Factor Structure as Ecological Structure in Helsinki and Boston.

It is a sociological commonplace to note that urban-industrial societies, regardless of differences in antecedent culture or in details of national history, tend to develop essentially similar social structures, and to undergo change in similar directions as a consequence of the working out of the same general processes in their specific socio-cultural settings. At the same time these specific socio-cultural differences--along with differences in resources, population societal scale and the like--produce larger or smaller differences in the detailed configuration of the basically similar structures in different societies or even within the same society from region to region, or at different points in time. Discovering the exact nature of these similarities and differences is the primary task of a comparative sociology of urban-industrial societies. But the identification of universal features common to all urban-industrial societies, and of less general features peculiar to a particular nation or a distinct stage in a process of change, requires the development of new methods of systematic comparative analysis. This paper proposes one such method, suitable for application to a limited, but important, phase of the problem: the comparative study of patterns of ecological differentiation among the residential sub-areas of urban communities.