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An Introduction to the U.S. Demographic System

An Introduction to the U.S. Demographic System. John F. Long www.usademography.com. Introduction. U.S. demographic system evolved over time: Rough guesswork in colonial times Decennial censuses since 1790 Birth and death registration in the early 1900’s

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An Introduction to the U.S. Demographic System

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  1. An Introduction to the U.S. Demographic System John F. Long www.usademography.com

  2. Introduction • U.S. demographic system evolved over time: • Rough guesswork in colonial times • Decennial censuses since 1790 • Birth and death registration in the early 1900’s • Estimates and projections in the last half of the 20th century • “Integrated” Accounting system implicit in the American Community Survey

  3. Inventory vs. Accounting • Inventory Approach • Population Stocks • Decennial Census Enumeration • Independent Counts • Mechanism of Population Change Ignored • Accounting Approach • Population Flows • Tracking of Components of Population Change • Estimates and Projections • Demographic Analysis • Combined Approach

  4. Decennial Census Counts An Inventory Approach

  5. U.S. Population: Census Counts from 1790 and Projections for 1860-1930 Source: U.S Census Bureau, Decennial Censuses 1790-1930 ; Abraham Lincoln, “Annual Message to Congress: December 1, 1862”.

  6. Need for an Accounting System • To estimate population change between censuses • To explain population change • To aid government and business policy and planning • To project future population • To plan and evaluate censuses

  7. Births Migration Migration Deaths

  8. Basic Demographic Accounting Px+1t+1 = Pxt + B (if x<0) - Dx + Ix - Ox where, Pxt is the population age x in a given place at time t B is the number of births in a given place between t and t+1 Dx is then number of deaths age x in a given place between t and t+1 Ix is the number of in-migrants age x to a given place between t and t+1 Ox is the number of out-migrants age x from a given place between t and t+1.

  9. Development of Demographic Accounting Approach • Nationwide birth and death registration began in the early 1900’s • Estimates and projections for states, counties, and places developed in the last half of the 20th century • Demographic Analysis became a key tool to evaluate decennial census quality • “Integrated” accounting system implicit in the American Community Survey for the 21st century

  10. Elements of US Demographic Accounting System • Master Address Files • Decennial Censuses • Birth and Death Registers (NCHS) • Immigration Data (INS & ACS) • Domestic Migration Data (IRS) • Adjustments and Corrections • American Community Survey

  11. Master Address Files • Importance of tying population to geography • Address canvassing prior to census year • Corrections during census operation • Updates between censuses • Provides “frame” for census and survey operations • Issues with permits, construction, demolitions, and conversions • Addresses vs. physical location.

  12. Decennial Census Counts • Base on which all of system is built • Provides ground truth check of accounting system • Key demographic data collected: location, relationship, sex, age, race, Hispanic origin

  13. Measure Death and Birth Components • Birth Registration • Ties birth to place of residence of mother • Race data is for parents not child – and uses older classification system • Completeness of registration is assumed • Death registration • Ties death to place of residence or last address? • Race is not self reported • Completeness and speed of tabulation is an issue

  14. Estimating International Migration Flows • Legal immigration • Difference between residence change and legal status change • Problems with place of intended residence • Completeness issues • Legal Emigration • Lack of data collection when leaving the country • Problems of using other countries data • Illegal immigration • Methods are often indirect • Question of census coverage • Alternative data from the American Community Survey

  15. Measuring Domestic Migration • Use of matched IRS returns to provide county in and out migration • Coverage of IRS data • Assigning age, race, hispanic origin, and sex data • Timing of data collection and tabulation

  16. Develop Yearly Population Estimates and Controls • Develop annual national, state, county, and place data for funding and other administrative uses • Provide county age, race, sex, Hispanic origin controls for the American Community Survey • Issues of timeliness and accuracy of input data

  17. Problems with an Accounting System • Errors in specifying the system can multiply over time • Errors in data input can cause faulty results • Structure of the system may change over time

  18. Factory Extra Inventories Shipping Fired Boss More Overtime Pay !

  19. Reconcile with new decennial census data • Need to recalibrate estimates from demographic accounting with decennial census results • Census coverage error vs. population estimation error • Incorporating “error of closure” corrections into new estimates.

  20. Reconciling Inventory and Accounting Systems • Audit of the current demographic accounts • Differences with a Population Register • Potential inconsistencies in the system • Future Hazards and Opportunities

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