The population growth model referred as the “Malthusian” model uses Birth
and death processes as the stochastic main components of population change.
The model gives rise to an exponential growth which assumes a constant
population growth rate and this can only work in the absence of any
constraints for a population to grow in a multiplicative manner. But in real life
the population change is subject to the internal and external forces such as
war, catastrophes and other natural disasters. Consequently, the population
projections and estimates under Malthusian were found to be far away from
the population true value and this affects negatively the planning process and
policy formulations. The development NPGR/APGR new methods were found
to be appropriate and effective since they generate the projections and
estimates that are closer to the true value. Upon the development of the new
methods, adjustment was made to the Malthusian model and then applied to
the real data of population of Rwanda and the estimates were found to be
closer to the true value at least 0.5% versus 4-16% for Malthusian model.