Shryock and Siegel (1973) and Morrison (1971) developed the following guidelines for performing population estimations and projections: The quality of information and data for a given locale, as well as the ability of the data to meet the basic assumptions of the analytic method are key to performing accurate estimates or projections. ^Top 5.2 Estimation and Projection Guidelines
This data can be divided into two categories: Direct information comes from census data and information on births, deaths, and migration. In most cases, they are based on de facto populations. In this case, it is much easier to explain the assumptions than it is to justify personal judgments about future conditions.Įstimates and projections can be for de jure (usual resident) or de facto (physically present) populations. Population estimations and projections are based on the assumptions of the tools rather than judgments of future trends. The tools covered in Lessons 5-8 do not include population forecasting.
For example, if planners expect births to decline in the future, they can modify the age-specific fertility rates when projecting population by age and sex. Planners who choose to forecast may modify the data employed in a projection to reflect their judgment of future trends. Forecasting requires knowledge about past and present social, economic, and demographic trends. The accuracy of estimation and projection tools is based on the rules and assumptions that are embodied in the method used.Ī forecast is a projection that includes judgment statements concerning the future. For example, the population cohort projection method can be used to calculate the population size of males and females by 5-year age groups. While estimations tend to calculate the total population size of a locale, projections calculate the total population size as well as the size of various segments of the population. Population information for past, present, and future conditions can be used to make a projection about the population. Information that reflects change in population size such as the number of housing units, postal or mailing addresses, registered voters, school enrollment, and users of metered water and other utilities.Ī projection is a calculation of the size of the population for a future date in time.Components of population change, including migration, fertility, and mortality.A post-census estimate is typically conducted for the current year.Įstimates involve the use of data that are based on the following information:.An inter-census estimation is for a date between two census takings and usually takes the results of the two censuses into account.There are two types of estimation techniques: inter-census and post-census. What Is the Difference between an Estimate, a Projection, and a Forecast?Ī population estimate is a calculation of the size of a population for a year between census periods or for the current year. 5.1 Estimates, Projections, and Forecasts The lesson concludes with the application of two estimation tools: an inter-census technique for estimating the midyear population and a post-census estimation using the housing unit method. The latter is necessary to calculate vital rates such as the general fertility rate and age-specific fertility rates for different time periods.
1925 NEW YORK CENSUS OA HOW TO
It demonstrates how to calculate both the current population size of a locale and the midyear population size between census periods. It discusses the difference between estimating, projecting, and forecasting the population and provides guidelines for performing accurate estimations and projections.
This lesson focuses on ways to estimate and project the population size of a locale. Skills to estimate population size for two periods in time, the current year and a year between census periods.