Why Estimates Differ From Site to Site
Population Estimates for Alaska are produced by the U.S. Census Bureau, the Alaska Department of Labor, and some municipalities. These different series may be similar or they may differ. There are several reasons for the differences, and the user should weigh all of the following factors in picking estimates.
Definitions of Residency: The U.S. Census and the Alaska Department of Labor both estimate permanent full-time residents for Alaska. The number of people temporarily in the state can vary by as much as 20 percent, and some communities may be much more seasonal because of the tourism, fishing, timber, and construction industries. If an individual's usual place of residence is in another state but that person works or lives part of the year in Alaska, that person is not counted as an Alaska resident in these estimates. Some communities may count such people in their estimates.
Different Geography: Different agencies making estimates may define a place with the same name in different ways. The most common form of census error is in defining a geographic boundary accurately or locating individuals relative to a map boundary. Sometimes boundary changes such as city annexations are not corrected before the deadline for producing an annual estimate.
Different Timing of Indicators: Because of the timing of the collection of administrative record indicators, the indicators used in estimates may vary in how current they are. Some U.S. Census Bureau estimates, for example, are made with indicators that are a couple of years old because of the time it takes for the information to reach the bureau from the collecting agencies. Estimates may obviously be made at different times of the year. Because population is constantly changing, estimates produced at different times of the year may differ.
Different Estimate Methods: As indicated, most estimates are produced using administrative record indicators of population change. Different series of indicators used to produce estimates will give somewhat different information. Some estimates, however, are generated by sample survey techniques or may be based on estimating population using housing and households. Some estimates for small places are produced using complete count information.
Different Purposes for Estimates: Most of the time, estimates are produced for planning purposes, and the intent is to produce the most accurate estimates possible. Once in a while, estimates or projections will be produced or commissioned to promote a particular project or community. As a result, the user should always consider the purpose of the estimates.