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Chapter 10: Population Estimates, Projections, and Forecasts - Coggle…

- - - - Population forecasts can apply to the short, middle, and long term
        
        Forecasting techniques are usually classed as either quantitative or qualitative
        
        Forecasting takes us beyond population science and into other fields such as business, economics, and technology studies
- - - - Employs the basic concepts and techniques of matrix math
        
        Po x L = Pt
- - - - Estimates are necessary because it is practically impossible to collet data continuously, especially the amount and type gathered by government census operations
        
        Central date: The point in time for which authoritative data on demographic characteristics exists
        
        The size of a population at midyear of that central date is used as the denominator of crude birth rates, death rates, and other measures
        
        A projection depicts likely population characteristics at a future date based on a set of explicitly stated assumptions about what is expected to occur between the time of the projection is made and the date to which it applies
        
        A forecast is neither fact nor sheer fiction.
        
        It is an assessment of a future state of affairs, including the future state of population characteristics, based on any or all of several sources.
- - - - Extrapolation: The process of estimating or projecting from a central date that assumes that growth will continue according to one of the growth models
  - - - Assume the net migration is zero
        
        By ruling out-migration as a growth component, it's easier to understand how one applies an already fairly complex technique
- - - - Growth = Natural Increase + Net Migration
  - - - Cohort Survival Method
        
        Assumes a closed population in which net migration is set at zero
        
        Cohort Survival
        
        Employed to estimate the size of each cohort and of the population 10 years later
      - Components Methods that Include Migration
        
        The Components II Method
        
        The Administrative Records Method
        
        The Ratio Correlation Method
  - - - Pt = Po x e^GR x t
        
        The basis for estimates and projections that assume a continual increase in the rate of growth between two dates
    - - Pt = k/[(1+b) x (e^-aT)]
        
        The basis for estimates and projections that assume that the rate of growth increased to a maximum and then decreases until it nears or reaches ZPG
    - - The Geometric Series
        
        Pt = Po x (1+GR)^t
        
        The basis for estimates and projections that assume a periodic increase in the rate of growth between 2 dates
    - - The Linear Model
        
        Pt = Po + (Po x GR x t)
        
        Assumes that the rate of change between 2 dates will be constant throughout the interval
- - - - Projection
        
        Forecasting