## ERIC - Projections of Education Statistics to 1985-86., 1977

The mean absolute percentage error is one way to express the forecast accuracy of past projections. This measure expresses the average of the absolute values of errors in percentage terms, where errors are the differences between past projections and actual data. For example, based on past editions of *Projections of Education Statistics*, the mean absolute percentage errors of public school enrollment ingrades prekindergarten-12 for lead times of 1, 2, 5, and 10 years were 0.3, 0.6, 1.3, and 2.6 percent, respectively. In contrast, mean absolute percentage errors of private school enrollment in grades prekindergarten through 8 for lead times of 1, 2, 5, and 10 years were 3.5, 4.9, 9.2, and 7.9 percent, respectively. For more information on mean absolute percentage errors, see in appendix A.

**Population estimates and projections**. Population estimates for 1980 to 2009 and population projections for 2010 to 2020 from the U.S. Census Bureau were used to develop the state-level enrollment projections. The set of population projections used in this year's *Projections of Education Statistics* are the Census Bureau's set of interim state-level population projections by age and sex (April 2005). In order for the state-level population projections to be consistent with the most recent historical estimates released by the Census Bureau, these projections were adjusted to line up with the most recent historical estimate for each state. This was done through the use of ratio adjustments in which, for each combination of state, age, and sex, the population projections from 2010 to 2020 were multiplied by the ratio of the population estimate for 2009 to the population projection for 2009.

## US Dept of Education Projections of Education Statistics to 2022 1

This edition of *Projections of Education Statistics* contains projected trends in public elementary and secondary enrollment by grade level from 2009 to 2020 for each of the 50 states and the District of Columbia, as well as for each region of the country. The state enrollment projections were produced in two stages:

This edition of *Projections of Education Statistics* provides projections for key education statistics, including enrollment, graduates, teachers, and expenditures in elementary and secondary public and private schools, as well as enrollment and degrees conferred at postsecondary degree-granting institutions. Included are national data on enrollment and graduates for the past 15 years and projections to the year2021. Also included are state-level data on enrollment in public elementary and secondary schools and public high schools from 2003, with projections to 2021. This report is organized by the level of schooling with sections 1, 2, 3, and4 covering aspects of elementary and secondary education and sections 5 and 6 covering aspects of postsecondary education.This edition of *Projections of Education Statistics* provides projections for key education statistics, including enrollment, graduates, teachers, and expenditures in elementary and secondary public and private schools, as well as enrollment and degrees conferred at postsecondary degree-granting institutions.