4.2.17 Discussion Of Analysis
Through the building of the Charmville population model, it was possible to identify the endogenous factors which impact upon the population (noting that Annual migrating-out is exogenous). Changes to the initial population are produced through additions by birthing rate and dying rate, and deductions by rate of migrating-in and rate of migrating-out. There is low birthing rate. This has the effect of making contributions to the population but these are made at decreasing rates (on a percentage basis) over time.
The strategy adopted by the local government authorities is to allow greater numbers of migrants to come to Charmville to live. This is made possible through the issuing of an appropriate number of new building permits. The effect of this strategy is confirmed by providing feedback from the issuing of permits into the population model through a new auxiliary variable Expansion. In this way the ideal planned population growth and expected growth are aligned.
Whilst this strategy appears to produce the desired results, it may not make Charmville residents happy. It gives preference to outsiders to settle in Charmville. Further, it does not take into account the possibility that as the families of current Charmville residents grow they will need to settle in homes of their own. Other mechanisms would be necessary to allow for this. This suggests the need for a housing sector. Indeed, through the building of a module for calculating the numbers of building permits need we have begun to create a sector to help us analyse the need to build houses.
A range of other strategies might be investigated, including:
- Encouraging young mothers to have additional children. In the existing model, the proportion of females having babies in any one year is 3.5%, and remains constant throughout the simulation. A small increase in this proportion will result in a continued growth in population, possibly to the point where the ideal population and expected population align. In the last iteration of the population model, the variable Child-bearing proportion of females was established as Graph function. Investigating the extent to which the model is sensitive to Birthing is now a simple matter of setting Expansion to zero and inserting trial data into the Child-bearing proportion of females variable. This should reveal that a steady increase in Child-bearing proportion of females from an initial value of 3.5% to 3.9% over a 10 year period will provide the planned growth (without any increase in migrating-in).
- Increasing the dwelling occupancy rate from the current level of 2.1 per dwelling, through a scheme which provides incentives for children to live at home for longer periods. This might be achieved by an initiative which provides a campus of the University of Metropolis at Charmville, thereby encouraging students not to travel and live in Metropolis.
Each of these possible strategies can be accommodated by relatively simple changes to the Charmville population model.