State and County Population Projections ASDC Annual Meeting Carolyn Trent, Socioeconomic Analyst Alabama State Data Center Center for Business and Economic Research November 2, 2012 Culverhouse College of Commerce and Business Administration The University of Alabama
Population Projections • Based on population change between the 2000 and 2010 Censuses and recent birth and death data. Assumptions are made about future trends in fertility and mortality. • Utilize a cohort component model of the form: Pop(new) = pop(old) + births – deaths + in-migration – out-migration • Calculated for the state and counties for 5-year age groups from 0-4 to 80-84 and 85+, for males/females, races white/black and other.
Inputs to the Projections • For the state and each county, the following are compiled: • Population by age/race/sex for 2000 and 2010. • Total number of births by race of mother and sex of child for 2000 through 2010 (from Alabama Center for Health Statistics). • Total number of deaths by race, sex, and age group for 2000 through 2010 (from ACHS). • Census 2000 and 2010 group quarters populations.
Census data inputs • We use bridged-race population estimates from NCHS instead of raw Census data. • These data are calculated by the Census Bureau for NCHS annually to create race categories that are more compatible with race information collected on state vital records. • Collapses the 31 race categories collected in the Census into 4 categories: White, Black or African American, American Indian or Alaska Native, and Asian or Pacific Islander. • The NCHS groupings reallocate the multiple race and some other race Census categories. Hispanics often identify themselves as some other race. • Census 2010 data have Alabama with 3,275,394 white and 1,504,342 black and other residents. The bridged 2010 data give 3,399,975 white and 1,379,761 black and other residents.
Fertility Rates • Using annual birth data by race of mother and sex of child for 2000 to 2010, we calculate the following for the state and each county: • General fertility rate by race for women aged 15 to 44 in 2010, using average births from 2006 to 2010. • Birth rate adjustment factors by race for each 5-year period, based on factors calculated by the Census Bureau for their most recent national projections. • Share of births by race that are male versus female, based on all births from 4/1/2000 to 4/1/2010.
Mortality Rates • We begin with annual death data by 5-year age groups, race, and sex for 2008 to 2010 for the state and each county and calculate: • A one-year mortality rate for each age/race/sex category by averaging the three years of deaths and dividing by the 2010 population. These are converted to multi-year rates. • Mortality adjustment factors for each 5-year period, using actuarial tables from the Social Security Administration. • We substitute in state rates for cells with fewer than 5 deaths on average.
Special Populations • Populations of people in prisons, colleges or universities, or other large institutions are not influenced by the usual demographic factors. • For 18 Alabama counties where at least 2.4 percent of the total population lived in group quarters, special populations were estimated for 2000 and 2010 by age, race, and sex. • These populations were held constant across the projection period. • Fertility rates were adjusted in counties with large university populations.
Producing Projections • The cohort-component program is run separately for each geography, generating projections for 5-year intervals from 2015 to 2040. • The cohort aspect of the projection process is that the population in each 5-year age group is aged over the 10-year intercensal period—i.e., individuals who were 20-24 in 2000 will be 30-34 in 2010. • The unknown part of the projection is migration rates, which are derived as the residual of the change from 2000 to 2010 after adding births to the 2000 base population and subtracting deaths. • Migration rates are dampened for each 5-year projection period under the assumption that the rate of people leaving a county will slow over time as will the rate of individuals moving in. • In this new series of projections, county results are summed across all age/race/sex groups to derive the state totals.
What demographic factors will be at play over the next 30 years? How will Alabama’s population be changing? Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 9
Baby boomers will be turning 65 from 2011 through 2029; retirements will open up jobs for Generation Y Source: U.S. Census Bureau. Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 10
Our population is aging due to demographic factors and longevity increases • Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 11
Alabama’s median age rose from 35.8 in 2000 to 37.9 in 2010 Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 12
Baby Boomers move from ages 46-64 in 2010 to ages 61-79 in 2025 Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 13
In 2040 Gen X will be 58-75 and ages for the larger Gen Y will hit 39-57 • Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 14
A relatively older white population is contributing to slower growth going forward • Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 15
Some counties will thrive over the next 30 years, while others will dwindle Economic development successes, local entrepreneurship, quality of life enhance-ments, retiree attraction, and workforce skills training could improve these trends Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 16
31 Alabama counties lost population between 2000 and 2010. Population change between censuses ranged from a gain of 36.1 percent in Shelby County down to a loss of 16.1 percent in Lowndes County. Alabama population growth was 7.5 percent. Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 17
Most projected growth from 2010 to 2040 will occur in metro area counties. Out-migration and aging will contribute to continued losses in rural counties. Alabama’s population is forecasted to increase 16.5 percent. Alabama State Data Center | Center for Business and Economic Research, The University of Alabama 18
Small area population projections • CBER can calculate population projections for areas down to the block group level. These are done on a contract basis. • Change between the two most recent censuses is used as a starting point. • A variety of other information, including building permits, infrastructure development, and recent or upcoming economic development are collected for the geographies to be projected. • ACS data, such as age of housing stock and income levels, is also used. Land area and housing density are examined. • CBER small area projections have been used for regional transportation plans and in socioeconomic impact studies for highway projects.
Check website for data • Projections are posted to CBER website http://cber.cba.ua.edu under Data, Maps, and Presentations. • They can also be accessed from the ASDC site’s Data section. • Detailed age/race/sex projections will not be posted due to their size, but will be available on CD from CBER for purchase. Thank you!