Typically, achievement gaps between groups of students are measured as either differences in average scores or differences in proficiency rates. But, practitioners, policymakers, and researchers have long recognized that these approaches don't tell the whole story. Average scores, for example, are good at summarizing trends but can mask real…

This letter is an interim response to the October 7, 1991 request from the Committee on Education and Labor and the Subcommittee on Elementary, Secondary, and Vocational Education of the House of Representatives asking for a review of the National Assessment Governing Board (NAGB) achievement levels for the National Assessment of Educational…