Population Projections Flashcards
On average, there are ____ births every 8 seconds
1 birth
On average, there are _____ deaths every 11 seconds?
1 death
On average, how many international migrants (net) every 32 seconds?
1 migrant
What’s the net gain of one person ever _____ seconds?
15 seconds
What’s the main purpose of the Census?
Determine population for congressional electoral districts.
What repalced the long form census in obtaining socioeconomic information for tracts and up?
American Community Survey
How often is ACS done?
Every year; however, not the same group every year; therefore, to get a statistical average, you must look at results from several years of ACS data. Every five years for tracts.
This method takes the population estimate of a larger area and uses proportion/ratios to estimate for a smaller area?
Step down method. Uses utilty hookups and drivers licenses, etc.
What is the typical population representation method?
Population triangle
Total number of births/population.
Total number of deaths/population
Total migration/population
Crude birth/death/migration rate.
Refined crude rates.
Measure of degree of population replacement
Nnumber of births/female population in childbearing years.
avg. US repalcement rate = 2.1
Fertility Rate (can be age specific)
What are the two fundamental drivers of population change?
Natural Change = Births - Deaths
Net Migration = immigration - outmigration
Population projection method where you take past rates and just extend into the future indefinitely.
Linear, exponential, and Gompertz methods
Population growth is exponential - NOT linear. Exponentital function used for fast-growing population.
Gompertz function (biology) has a carrying capacity, “S”-shaped curve that levels off at carrying capacity.
Trend Extrapolation
Projection based method where you take large population rate/data, use an identified ratio, and apply to a smaller area.
Ratio Method (step down) - small area proportional to larger area.
Distributed Housing Unit Method -
Pop(t) = housing units(t) X occupancy rate X household size
Use above-method with your building permit data, etc. Planners have good data on number of households.
Allocation Method
(Fundamental) Population Equation
Pop(t+1) = Pop(t) + Births(t to t+1) - Deaths(t to t+1) + net migration (t to t+1)
Population is just the population at one time + births at that time - deaths at that time + migration at that time.
Migration is much harder to track than births and deaths. Weakest part of population projection.
Best projection method.
Cohort Survival/Cohort Component
