Scaling is the process of constructing a score scale that associates numbers or other ordered indicators with the performance of examinees. Scaling typically is conducted to aid users in interpreting test results. This module describes different types of raw scores and scale scores, illustrates how to incorporate various sources of information into a score scale, and introduces vertical scaling and its related designs and methodologies as a special type of scaling. After completion of this module, the reader should be able to understand the relationship between various types of raw scores, understand the relationship between raw scores and scale scores, construct a scale with desired properties, evaluate an existing score scale, understand how content and standards information are built into a scale, and understand how vertical scales are developed and used in practice.
Keywords: item response theory, IRT, linear transformation, nonlinear transformation, raw score, scale score, scaling, score precision, score reporting, vertical scaling