Before logistic model
After the discussion of the background information relating to population projection, we are going to take a close look at one of the most famous mathematical models for population projection ---- the logistic model. In order to understand the logistic model, we need to understand exponential model first, since the logistic model is developed based on the exponential model.
The significance of the exponential model is to reflect a geometric population growth, which is inherited by the logistic model. The geometric population growth is first proposed in 1798 by Thomas Robert Malthus in his An Essay on the Principle of Population, as It Affects the Future Improvement of Society, With Remarks on the Speculations of Mr. Godwin, Mr. Condorcet and Other Writers. He stated that “Population, when unchecked, increased in a geometric ratio.” He also believed that “Subsistence increases only in an arithmetical ratio.” Therefore, Malthus predicted that human society will eventually end up with famine. This publication had tremendous influences on studies of population and it made Malthus become the founder of the exponential population model.
