The “Demographic Transition” is a model that describes population change over time. As with all models, the demographic transition model has its applications and limitations.
– The model describes population change over time and can be applied to many countries (based on the change in crude birth rate (CBR) and crude death rate (CDR) over time)
– Can be used for comparison and also prediction from stages 1 to 4
– Outline the population characteristics of societies at various stages of the development
– Population structures can be related to the model
– The model is often applied to lesser developed countries to allay concerns regarding overpopulation, without proof that the underlying dynamics will allow these countries to trace similar evolution paths as the European and other Western countries.
– Birth rates in several MEDCs have fallen below death rates (Germany, Sweden). This has caused, for the first time, a population decline which suggests that perhaps the model should have a fifth stage added to it. However the model does not go beyond Stage 4.
– The model assumes that in time all countries pass through the same four stages. It now seems unlikely, however, that many LEDCs, especially in Africa, will become industrialized
– External influences are not considered. The model assumes that the fall in the death rate in Stage 2 was the consequence of industrialisation. Initially, the death rate in many British cities rose, due to the unsanitary conditions which resulted from rapid urban growth, and it only began to fall after advances were made in medicine. The delayed fall in the death rate in many developing countries has been due mainly to their inability to afford medical facilities. In many countries, the fall in the birth rate in Stage 3 has been less rapid than the model suggests due to religious and/or political opposition to birth control (Brazil), whereas the fall was much more rapid, and came earlier, in China where the government introduced the one child policy.
– The timescale of the model, especially in several south-east Asian countries such as Hong Kong and Malaysia, is being squashed as they develop at a much faster rate than did the early industrialised countries.
– The model assumes that all countries will go through the stages 1 to 4 in that exact order. There are variables and exceptions such as war and turmoil that may lead to different results. Some countries may even skip stages – Eg. Countries that grew as a consequence of emigration from Europe (USA, Canada, Australia) did not pass through the early stages of the model.
– The model only reflects natural increase. Eg. There was a major migration overseas during a time period in the UK, where millions were unemployed – had an effect on the population on its age structure and as a whole.
– The model does not forecast changes or provide explanations as to why one stage might lead to the next.
– The DTM is also limited in the sense that it gives a generalized picture of population change over time based on European studies, assuming that all countries would follow suit.