|Figure 21-2: Percentage distribution of source of variation in instruction expenditures per student in unified public elementary and secondary school districts: Selected school years, 1989-90 through 2008-09|
NOTE: The Theil coefficient measures variation for groups within a set (i.e., states within the country) and indicates relative variation and any differences that may exist among them. It can be decomposed into components measuring between-state and within-state variation in expenditures per student. It has a minimum value of zero, and increasing values indicate increases in the variation, with a maximum possible value of 1.0. For more information on the variation in expenditures per student and the Theil coefficient, see Appendix C – Commonly Used Measures. For more information on the Common Core of Data (CCD), see Appendix B – Guide to Sources.
SOURCE: U.S. Department of Education, National Center for Education Statistics (NCES), Common Core of Data (CCD), "NCES Longitudinal School District Fiscal-Nonfiscal (FNF) File, Fiscal Years 1990 through 2000" and "School District Finance Survey (Form F-33)," 2004–05 and 2008–09.