Which of the following aspects does the Demographic Transition Model NOT focus on?

The Demographic Transition Model primarily emphasizes the relationship between fertility and mortality rates, population age structure, and the broader societal changes that accompany industrialization and urbanization. These aspects are critical in understanding how a population evolves through different stages, from high birth and death rates in pre-industrial societies to lower rates in more developed economies.

Population migration patterns, on the other hand, are not a focus of the Demographic Transition Model. Though migration can impact population size and demographics, the model itself is mainly concerned with changes in birth and death rates and the transitions that occur as a society develops economically and socially. Thus, the model does not directly address how migration influences demographic changes, which sets it apart from the other aspects that it does cover.