Oregon -- Population -- Statistics, Demographic surveys -- Oregon
As mandated by Oregon law (ORS 190.510 to 190.610), the Center for Population Research and Census at Portland State University, acting on behalf of the State Board of Higher Education, annually estimates the July 1 population for each county and incorporated city in Oregon. These population estimates are used in the allocation of certain state tax revenues to cities and counties.
Population figures presented in this report represent all the people who usually reside in the area designated. This includes people living in correctional institutions, nursing homes, and college dormitories. College students are considered residents of the place where they live while attending college. Seasonal populations, such as people living in summer homes, are counted as residents of the place they consider their usual residence.
Population estimates are developed as accurately as possible from standard and tested methods. The specific procedures used depend on the availability of state and local data. State estimates for Oregon are developed by a component method. This technique estimates the population of people under age 65 using two components. The first component is a compilation of vital events (i.e., births and deaths) and the second component is an estimate of net migration into Oregon based on the migration of school-age children. Medicare data are used to estimate the population of those age 65 and older.
County population estimates are determined primarily by the ratio correlation method: this method relates the change in population since the last census to the changes in a set of symptomatic data. The current equation contains state tax returns, school enrollment, births, and voter registration. Changes in the symptomatic data for each county are tracked since the last census to estimate the county's population. County population estimates based on the component method, and changes in housing stock since the last census are also considered, although substantially less weight is given to these estimates.
City population estimates are determined by the housing unit method. Each year, cities report to the Center the changes in their housing stock and the count of persons residing in group quarter facilities (e.g., correctional facilities, college dormitories, and nursing homes). The Center adds in any . population and housing changes caused by annexations. The 1990 U.S. Decennial Census provides benchmark data for each city on the number of housing units, the average number of persons per housing unit, and the number of persons residing in group quarter facilities. These data are updated annually and help the Center determine accurate estimates of a city's population.
Wineberg, Howard and Population Research Center, Portland State University, "Population Estimates for Oregon: July 1, 1997" (1998). Oregon Population Estimates and Reports. 74.