| Abstract: | Norm-referenced standardized achievement tests are designed, and commonly used, for obtaining group scores. Various methods are used to calculate and express group scores in terms of common derived scores, such as percent ile ranks. Publishers' scaled scores are ordinarily used in these procedures, with the result that the group scores can possess anomalous characteristics. The group scores can vary widely, depending on not only the measure of central tendency but also the type of derived score employed. A reason for this situation is hypothesized to be the use of inappropriate statistical procedures to develop publishers' scaled scores. Practitioners need to be aware of this problem and to document their procedures when calculating and reporting group scores. Test publishers are urged to avoid the use of scaling procedures that are seen as responsible for this problem. |
