Why use scale scores?
The advantage of using scale scores rather than raw scores or percentage reporting is that the scale makes it possible to compare results from different tests, as long as they are measuring the same variable (that is, the same collection of skills, knowledge and understanding). Using scale scores, we can compare the performance of students in different grades in the same year, of a particular grade from one year to the next, or of the same students from one year to the next.
