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POPULATION ESTIMATES, PROJECTIONS, AND FORECASTS - Coggle Diagram
POPULATION ESTIMATES, PROJECTIONS, AND FORECASTS
Demographers employ several techniques in attempting to understand how pop-ulations at a future date (or at a date later than that for which data are available) will resemble or differ from their current state.
These are generally classed into three categories, each of which is based on a specific set of assumptions and mathematical formulations: (1) estimation, (2) projection, and (3) forecasting.
To understand the past rather than to predict the future; apparently the way to think effectively about a set of observed birth and death rates is to ask what it would lead to if continued.
Central Date
The point in time (usually the most recent point) for which authoritative data on demographic characteristics exists.
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 the projection is made and the date to which it applies.
Forecast
An assessment of a future state of affairs, including the future state of population characteristics, based on any or all of several sources: projection, scientific theory, intuition, and even sheer guesses.
Population Estimate
An assessment of a population’s size or other characteristics at a present or near-future date, for which we have no immediately current information.
stimates are actually updates of old data, based on the most recent data available.
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Exponential Growth
Traces the smooth, upward sloping curve.
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Logistic Growth
Assumes that neither absolute growth nor growth rates remain constant over the period under observation.
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