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Section V. Draft Countv Profile (Data) Element Orange Countv Comprehensive Plan C Projections C1?. Population Projections Background • Population Projections are educated guesses or estimates for future population based on sets of assumptions about potential growth. Projections provide an important framework for estimating the extent of future impacts on human, economic and environmental conditions resulting from the increased demand for the use of land and resources. To maintain objectivity and provide different scenarios for future growth trends, alternative methods have been used for the County Profile Element, yielding a low, medium, and high projection of future population growth. • Population projections maybe provided in {} to reflect the range of values yielded through different projection methodologies. Methodology • Adjusted Migration Model: a sophisticated methodology based on a series of assumptions and controls as prepared by the NC Office of Budget, Planning and Management, Demographic Section. This model takes into account factors such as migration rates, births; deaths, age - cohorts, institutional effects (such as university enrollments), growth trends and growth estimates. • Exponential extrapolation - uses the average annual growth rates between the decades of (1980 -1990) and (1990 - 2000). While more sophisticated methods exist, the relatively simple extrapolation formulas have been found to be accurate in predicting future population size, particularly in fast - growing areas with sub -areas of less than 100,000 persons. A more detailed explanation can be found in the Appendix. • Linear extrapolation: assumes population will change by identical increments in each interval of future time and is calculated based on the average population change in the decades (1980- 2000). This method is considered to be an accurate method for moderately growing areas, at a rate of up to 25 %. A more detailed explanation can be found in the Appendix • The Exponential and Linear population projections contained herein are based strictly on previous mathematical growth rates, and do not include adjustments for amount of developable land; economic trends or conditions; current land use policies; and/or other similar factors. The constraints of land and policy on projected populations will be factored in as coordinated land use conditions and policies unfold. An average of the Exponential and Linear population projections is provided as an example in the comparative chart. 9/6/2007 cl