Socio-Economic Tools - Population Measurement
This section offers a number of tools and techniques which can be used in determining the future trends of the community. This section is not intended to be a textbook on projection techniques and methodologies. It is intended to provide examples that can be used in measuring future trends of the community .
Population projections are the foundation upon which planning decisions are based regarding the demand for future public and private services. Population projections demonstrate if an area will experience increases or decreases in their population. Typically population projections are made for a twenty year period with five to ten year intervals. The following tables and graphs demonstrate the use of population projections over a thirty year period including a table which analyzes population changes in the number of persons and by percentage. Population projections are usually available from a number of different sources including: state planning agencies; regional planning agencies; councils of government; state transportation agencies; state water resources agencies; universities or companies who develop and provide population data for a fee. Municipalities can also develop their own population projection using a variety of available models or basing projections on past growth patterns and the availability of land for future development.
Population Density Forecasts- (in persons per square mile)
These forecasts are relatively easy to derive using population projection data and the area of the municipality. See attached table.
House and Household Size Forecast
This provides interesting and useful information on the number of new household formations (an important factor in housing and other service demands) and household size. This projection information is fairly sophisticated to develop and would usually only be available from a state, regional, or county planning agency which routinely develops these types of projections.
Employment Projections- Employment projections are another important indicator of the economic growth and health of the community. These data are usually developed by employment sectors such as retail, office, industrial, federal government, state and local government, self-employed and other. This information may be available at a variety of different size areas ranging form counties to sub-planning areas. This information is difficult to develop and will usually only be available from state, county or regional planning agencies.
Information on changes in employment by numerical change and percentage may also be available and portrays the projected economic growth in the community. See attached table.
Build Out Projections
Build out data is a blend of population and housing data which demonstrates increases in population and housing over a period of time and measures whether either will meet or exceed a created build out figure for the municipality. This can be an effective indicator of a communities need to employ growth management techniques to manage or slow down growth if projections will exceed the community's build out over the next twenty years.
Future housing needs are determined by three factors: population growth, vacancy rates, and persons-per-household trends. Reduction in housing vacancy rates reduces the need for additional new housing construction by using more of the existing housing stock to accommodate projected population growth. However the decline in vacancy rates can be offset by a reduction in person-per-household ratios, which is occurring throughout the United States. A reduction in persons-per-household results in the need for more dwelling units to accommodate the same population.
The three factors of population growth, vacancy rates, and persons per household allow for a reasonable forecast of the demand for additional housing in a municipality. The attached tables demonstrate the historical and projected population, vacancy rates and persons-per-household trends and the resulting housing unit projection
Housing projections can be developed based upon the information and techniques described above. They are also usually available from state, regional and county planning agencies.