The current set of population projections for the state and its counties was released by the North Carolina Office of State Budget and Management in September of 2011 and updates the release of May 2011. This projection series uses a new model from that used in previous years. State and county total population projections are now made using times series trends (exponential smoothing and ARIMA models).
Like the previous model, this model considers both the trend growth of 1990-2000, the annual non-institutional growth from July 1, 2000 through July 1, 2009 derived from the set of July 2000-2009 Smoothed County estimates (intercensal estimates) and the July 1, 2010 Certified population estimates released by the State Demographer in May/September of 2011, as well as the 2000 and 2010 Census. For the current set of projections, the assumption is that migration (and, hence, growth) for July 1, 2011 through July 1, 2031 is also a function of the "trend" growth based on the 1990-2010 base decades, and the average annual non-institutional growth through July 1, 2010 derived from the set of July 2010 Certified County Estimates which was released by the State Demographer in September of 2011.
For the current set of projections, an exponential smoothing or ARIMA model was selected that most accurately projected the 2010 Census while maintaining a low MAPE for each county using 1990-2010 data, and the county totals were summed to obtain projections for the entire state.
BASIC DATA.... Return to Index
The most fundamental basis for these projections are population values for North Carolina and its counties from the Census Bureau's 2010 Census of Population. Since the last projection series, there have been a few minor corrections based on Census Bureau boundary changes.
METHODOLOGY.... Return to Index
The basic county trend projections produced for this series were modified for the growth of certain institutions. Institutions such as colleges, universities, military installations, and, to a lesser extent, prisons and some state hospitals, house persons of particular age groups. These populations will substantially grow or decline only by administrative action. There are thirteen counties in North Carolina the age structure of which is significantly affected by institutions. These counties (with major institution type) are Avery (prisons and college), Craven (military), Cumberland (military), Durham (university), Jackson (university), Madison (university), New Hanover (university), Onslow (military), Orange (university), Pasquotank (university and prisons), Pitt (university), Wake (university and prisons), and Watauga (university).
Many counties, as well as the state as a whole, experienced some growth in institutional populations between 2000 and 2010. It was assumed that all institutional populations would remain constant after 2010.
Information contained herein is current as of October 5, 2011.