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Areas of Application
Social sciences
City Planning
Cities and other governmental agencies forecast tax revenues, infrastructure needs, and opera- tional expenses when setting their annual budgets. Whether predicting population changes, business usage, or housing needs, growth projection models help provide realistic estimates for budgeting purposes. They are also helpful when developing policies such as environmental protections and residential growth ordinances.
☞ The City Planning model is located at \Examples\Continuous\Standard Block Models. The model uses blocks from the Value and Plotter libraries.
Model assumptions
The City Planning model represents office occupancy in a city with a limited amount of offices. A projection provides the number of new businesses that will require office space each month over the next 240 months. There is also an estimate of the number of businesses that will fail.
• 4,000 offices are initially available
• Each business requires an average of 5 offices • 2% of the businesses fail each month
About the model
The model examines how many of the businesses will be able to occupy offices, the number of businesses lost because offices are not available, and what effect business failures have on the availability of offices. This model is notable because it mainly uses the Math block, rather than the Equation block, to calculate data. That way the relation- ships and calculations that occur in the model are shown explicitly.
City Planning model
Growth projections (see the Lookup Table block labeled “Demand”) are derived from a study estimating growth over a 20 year time period.
For clarity, this model is separated into sections:
• OfficeBank:TheHoldingTankrepresentsthenumberofofficesavailable.Theinitial amount of 4000 is reduced as businesses occupy offices and is increased as businesses fail. Multiplying the demand for offices by the expected number of offices required per business (5) gives the amount that will be withdrawn from the office bank. If there are not enough offices available, businesses cannot relocate to this city. These “lost businesses” are also cal- culated.
• BusinessesOccupying:Thenumberofofficesoccupiedeachmonthisdividedbythenum- ber of offices required per business (5) to determine the number of businesses that occupy

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