Standardized achievement testing is intended to provide an objective assessment of how much students have learned in school. The results of these tests are usually interpreted using norm-referenced comparisons of a nationally representative sample of students, although some standardized achievement tests also provide absolute standards. These tests are available from several different publishers and provide information about the individual student, the entire school, school district, or state. Standardized achievement tests are usually accompanied by precise instructions for administration and scoring. They generally are intended for commercial purposes, although not all such tests were constructed for this reason.