ABSTRACT
Any purposeful statistical investigation of a phenomenon requires a special conceptual apparatus, a theory, that will enable the investigator to select from among the numberless multitude of facts those that prospectively fit into some pattern and hence are susceptible to systematization. Even such a relatively simple event as a shift in population must first be placed within a rather complicated conceptual framework before it can be dealt with directly in a statistical investigation. The more complicated the object of inquiry, the more important its theoretical “preparation”, so to speak. Accordingly, we too are obliged to erect the requisite theoretical framework before we proceed to the purely statistical aspect of our topic.
