Vertical Scaling

In educational measurement, evaluation of students’ growth in knowledge, skills, or aptitude over time has important implications to educators and policy makers. One common method of measuring growth is through the use of vertical scales. Vertical scaling is a special form of linking, which aims at adjusting score differences on tests that differ in content and/or difficulty. Successful linking enables educators and researchers to make statements such as “a score of 155 on Test X corresponds to a score of 365 on Test Y,” where the content specifications in Tests X and Y need not be exactly the same. Vertical scaling is intended to establish the concordance relationship between scores on tests measuring educational achievement or aptitude at different academic grades. Proper vertical scaling enables ...