Cohort Survival Demographic Models

1
Cohort SurvivalDemographic Models

• CP 6019 Quantitative and Computer Methods

2
Basic Components of Demographic Change

• Births from county vital records
• Deaths from county vital records
• Migration no ongoing source of information
• In migration
• Out migration
• Net migration

3
Cohort Categories

• Age cohorts
• 5, 10, 15, or 20 year cohort groups
• Sex male and female
• Race white, African-American, etc

4
Sources of Migration Rates

• Census long form information
• Regression equation based upon school enrollment,
  power connections, drivers licenses, etc.
• Estimate by residual method

5
Residual Migration Calculation

• Secure birth and death counts for historical
  period (1970 to 1990) and population at beginning
  and end of historical period (1970 and 1990)
• Take births minus deaths to get natural increase
• Calculate difference between 1970 population and
  1990 population, subtract natural increase
• This residual must be net migration

6
Cohort Model Principles

• Calculate birth, death, survival, and net
  migration rates for the historical period by age
  cohort (and race and sex cohorts, if possible)
• Apply those rates to the current population to
  calculate expected births, deaths, and migrants
  in the future
• Add the current population, births, and net
  migrants for each cohort, subtract deaths
• Sum over all cohorts for projected population