Description

The FIELD model incorporates population projection data transferred from Excel spreadsheets. Population estimates (1980 through 2006) and projections (2007-2011, 2015 and 2025) were prepared by the Hillsborough County City-County Planning Commission on September 22, 2006 for Plant City, Tampa, Temple Terrace and Unincorporated Hillsborough County. The values represent estimates and projections as of April 1st of each year.

The initial population value for 2007 in the FIELD model was based on the 2006 estimate plus a 1/19th share of the population change between the 2006 estimate and the 2025 projection. Projections for 2026 and 2027 were generated by extrapolating the linear trend from 2006 through 2025. The FIELD model uses the difference between the 2027 projection and the 2007 estimate as the population growth that the future land use plan has to address.

The Population Projections Module of the FIELD model is shown above. The Initial Population constant represents the population estimates for all jurisdictions in the year 2007 (the base year of the model). The Annual Population Change, or flow (meaning a rate of increase), is computed for each jurisdiction by subtracting the projected population for the year 2027 population from the 2007 population and then dividing by the number of years (20). This value is subsequently added to the Initial Population (2007) to obtain population projections for each year that the simulation is run in the level, Population. Auxiliary, Cumulative Population Change stores the cumulative population change for all the jurisdictions.

The table in the module above shows the following variables:

• Initial Population (2007 population)

• Annual Change (population)

• 2027 Population

• Cumulative Population Change (for each jurisdiction)

The graph below shows the cumulative population change from the year 2007 to 2027. The cumulative population change is shown in the box above the graph. The jurisdiction for the graph can be selected from the drop-down menu on the top left side of the graph.

Equations Used/Variables Used

• Initial Population (2007 population for each jurisdiction)

• Annual Population Change (for each jurisdiction)

• Population (2027 population for each jurisdiction)

• Cumulative Population Change = Population - Initial Population