Population Projections Matthew C. Harris, Ph.D. Center for Business and Economic Research Tennessee State Data Center Department of Economics Haslam College of Business University of Tennessee Nov. 18, 2014

Demographic Data - Sources Decennial Census American Community Survey Census Bureau Population Estimates Population Projections

Mandated by Article 1, Section 2 of U.S. Constitution Based on actual counts of persons Used to determine number of members in House of Representatives from each state Provides the base population for the annual population estimates series Decennial Census

Calculated number of people living in an area at a specific point in time. Derived using models that account for changes in: – Births – Deaths – Net Migration Used to control/inform ACS, CPS, etc. Used for denominators by state/local government agencies and non-profits as denominators in rate calculations and program fund allocations. Population Estimates

Estimates of the population for future dates Relies on assumptions about future births, deaths, and net migration. Used by government, business, and non-profits for planning purposes and demand forecasts. Population Projections

A ‘cohort-component’ model – Single Age – Sex – Race/Ethnicity - County Birth: county-age-race specific birth rates Death: Statewide death rates, augmented by SSA tables for changing life-expectancy. Net Migration – Use decennial census data. What We Do

Net Migration is Unobservable – Birth and death are documented in vital statistics ‘Tennessee Department of Health’ – Net migration is the ‘residual’ Population is known Births are known Deaths are known Net Migration makes up the difference Most volatile component of population change Most critical component of short-term population change. The Elephant in the Room

Tennessee State Data Center Census Population Estimates Where can you find projections

YearPopulationAnnual Growth % 19703,923, ,591,1201.7% 19904,877,1850.6% 20005,689,2831.6% 20106,346,1051.1% (estimated) 20136,495,9780.7% Where are we now Since 2010, the State has: grown more slowly than anticipated grown at its slowest rate in the last 20 years.

Net Migration: – : Average Net Migration of 40K – : Average Net Migration of 27K Births: – : Average of 84K per year – : Average of 79,588 per year Deaths: – : Average of 58K per year – : Average of 60K per year Overall: – : TN was 11 th fastest growing state in U.S. – : TN is 25 th fastest growing state in U.S. Short term fluctuations

Pending 2014 Pop. Est. release – – will probably contain some downward adjustment to reflect decreased net migration across the state. – Don’t want to let short term decreased mobility lead to over correction. – Last 3 years do not look typical – purpose of pop projections is to guide future planning efforts, not serve as a substitute for inter-censal estimates. – Long term picture for population growth is healthy: Non-farm employment is increasing. TN promise should increase our appeal as a business location – Upward trajectory should resume – not if, but when Revision

We model population growth as a pure population process. – Births – Deaths – Historical Net Migration We do NOT include structural economic factors: – Structural Economic Changes – Planned Development – Infrastructure Changes What We Do

To include economic data in a model, you need: – Consistent variables and consistent impact. An issued commercial development permit has to mean the same thing in County X as it does in County Y. – Accurate forecasts of all economic variables included. When accurate, including economic variables may be helpful. Forecast error in economic variables may (and often does) make overall population forecasts less accurate. – Most economic variables are even noisier than net migration. Incorporating them ALSO requires an understanding of who those variables bring in to a given county. – Population growth is actually a pretty stable process. If we know it matters...

CountyPopulation Change Davidson31918 Rutherford18425 Williamson15721 Knox12388 Hamilton12208 Shelby11825 Montgomery11788 Sumner8243 Wilson7955 Sevier3694 Volunteering Some Data... Biggest Gainers (Absolute Change) Since 2010 Decennial Census

CountyPopulation Change Roane-1133 Hardeman-947 Giles-739 Obion-676 Claiborne-653 Weakley-571 Greene-564 Haywood-563 Campbell-478 Hickman-432 Volunteering Some Data... Smallest Gainers (Absolute Change) Since 2010 Decennial Census

CountyPercentage Change Williamson8.5% Rutherford7.1% Wilson7.0% Montgomery6.8% Sumner5.1% Davidson5.1% Sevier4.1% Sequatchie4.0% Loudon3.9% Hamilton3.6% Volunteering Some Data... Biggest Gainers (Percentage Change) Since 2010 Decennial Census

CountyPercentage Change Hardeman-3.5% Haywood-3.0% Giles-2.5% Obion-2.1% Roane-2.1% Hancock-2.1% Claiborne-2.0% Hickman-1.7% Lewis-1.6% Weakley-1.6% Volunteering Some Data... Smallest Gainers (Percentage Change) Since 2010 Decennial Census

Middle Tennessee continues to lead population growth. – Urbanization/Suburbanization continue Tennessee is growing more racially diverse – but at a slower rate than the rest of the U.S. 2000: 13.5% of Tennessee residents were born outside the South. 2010: 20% of Tennessee residents were born outside the South. Overall Population Trends

State Population in 50 years intervals YearPopRatioAvg. Growth year Trend150 year Trend A very long term view