After World War II, some sociologists began to employ mathematical models as part of a deepening and broadening of the interpenetration of mathematics and the social and behavioral sciences. These applications were quite different from traditional data analysis wherein statistical procedures are the main tools. The idea was to create more rigorous scientific theories than had hitherto existed in these fields. Traditionally, for instance, theories in fields such as psychology and sociology were strong in intuitive content, but weak from a formal point of view. That is, assumptions and definitions were not clearly stipulated and distinguished from factual descriptions and inferences. In particular, there was rarely a formal deduction of a conclusion from specified premises.