In reviewing the material for this presentation, one of the principal references given for the topic of “Models” was that of Livingstone 1992, which above all else gives a good historical account of the Quantitative Revolution, and places subjects such as those of modelling into some context. To go further than this, however, will be to go over ground that has already been covered in a previous presentation.
We have also already established that the use of a model serves to provide a broad framework of explanation and which should contain relatively few variables and centred upon a range of common denominators within the field of study. In essence, to construct any model based upon too complicated a set of hypotheses and with too broad a range of variables defeats the very object and purpose, which is simply to establish a framework within which to work. A well constructed model with a firm methodology, a clear hypothesis and with a limited range of variables should enable the predictive qualities of it to become clearer.
To this end, we have chosen and agreed NOT to cover or regurgitate old ground, but rather to build upon it by introducing the concept of models within our discipline using three examples of them. Whilst acknowledging that there are many other models of equal stature, our approach will, we hope, will assist in giving a clearer understanding of the historiological context for each, together with an insight into how they were and are constructed and by whom. I shall therefore begin with one of the earliest models to be constructed and used, that of the Demographic Transition Model. Matt will then take this a step further with an analysis of Rostow’s Model which came much later in time. Rob will then conclude with a look at one of the most recent developments in model use – that of GIS.
In view of the foregoing, we would like you to listen carefully to each of the models presented, which we hope with your own background reading will be as informative as we have found to be interesting, and enable us all to see to what extent models have a place in the geography of today.
The Demographic Transition Model
The volume of research and application of models to attempt to evaluate and explain the existing demography of a population as well as future projections are too broad and diverse to be covered here. What I propose however, is to give a broad explanation of the use of models by demographers, how they have been developed and thus hopefully to stimulate some views and opinions on where the use of such models may direct us in the future. To further our understanding of the use of models in the field I’d like to examine, as a case study, the use the Demographic Transition Model. The use of it has assisted immensely in early attempts by geographers to benchmark the reasoning, spatial distribution and density of populations.
To place its use into a historical context as a conceptual model, it is generally accepted that one distinguishing feature of human cognitive function is that we seek rational explanation of reality in the patterning of perceived phenomena. Our perceptions of such phenomena are filtered through these structures or models, and we feel reassured if a pattern is there. Our urge to create such patterns, and where there are none – to create new ones, is possibly one of the defining characteristics of cognitive function. In this respect, early attempts at explaining demographic trends were founded upon the basis of diagrammatic and simple mathematical formulae and in essence were relatively crude, amounting to little more than a simple trend over time derived from the addition of new births and the subtraction of deaths.
However, the quantitative revolution that emerged in the 1960s witnessed a development in the range of attitudes and opinions in this field, as well as in others. A number of key players emerged to align themselves with what was being stated at that time and we will briefly cover them in a moment. Further, the emergence for example of industrialisation and increased mobility or “migration” in the developing world, together with the ability to grow more food with less using better technology, improved sanitation and an improvement and gradual eradication of previously life-threatening disease, had, over time, substantially altered the structure of a population. Thus, the need and desire to explain, and indeed anticipate the behaviour of a population became of critical importance. The development of theories and models to achieve this became increasingly more desirable and prominent.