1. Four Perspectives on Demographic Transition

2. Description (2) Classification
Demographic transition “theory” is strong descriptively. It was based on the description of secular trends in birth and death rates that were manifest in Western countries as they passed through the Industrial Revolution.
The demographic transition, as a framework, is useful for classifying populations. For example, a remote Amazonian tribe might fit in the pre-transitional stage, less developed nations, by definition, belong in one or other of the two transitional stages, and the more developed nations fit the post-transitional stage.

3. (3) Explanation (4) Prediction
Demographic transition “theory” is weak in explanation of population change. It does not specify the mechanisms of such change. Progress through the demographic transition is not automatic, and the “theory” fails to account for any reversal that might occur in the process.
Demographic transition “theory’ has informed prediction of population growth. Knowledge of this “theory’ has permitted demographers to predict accurately the rapid population growth of Asia, Latin America and Africa during the second half of the twentieth century.

4. Figure 3 Demographic/ Epidemiologic Transition Framework
The Egyptian-born demographer and health scientist, Abdel Omran, conceived the notion of the epidemiologic transition. Figure 3 reflects a four-stage depiction of the demographic transition and the superimposition of a four-stage epidemiologic transition. Omran’s epidemiologic transition comprised three stages. The additional stage combines the work of other demographers that acknowledges emerging infectious diseases, such as HIV, and the rising mean age at death in the more developed countries attributable to the prevention and improved management of heart disease and stroke.
References:
Abdel R. Omran. The Epidemiologic Transition: A Theory of the Epidemiology of Population Change. Milbank Memorial Fund Quarterly Vol. XLIX (4); 1971:
S. Jay Olshansky and Brian Ault. The Fourth Stage of the Epidemiologic Transition: The Stage of Delayed Degenerative Diseases. The Milbank Quarterly 64 (3); 1986:
Richard G. Rodgers and Robert Hackenberg. Extending Epidemiologic Theory: A New Stage. Social Biology 34 (3-4); 1987:
With appropriate acknowledgement of sources, permission to reproduce freely the three figures presented in this lecture has been granted by the Population Reference Bureau.
Source: Ian R.H. Rockett. Population and Health: An Introduction to Epidemiology. Second edition. Population Reference Bureau 54(4); 1999: 9