What are scaled scores, and how can they be compared between tests in the Assessment Series?

What are scaled scores?

Scaled scores on the CommonLit Assessment Series tests are scores that account for both the number of questions students answered correctly and the difficulty level of the questions on a test. This ensures that students’ scores reflect their abilities even if one Assessment Series test is slightly easier or harder than another.

CommonLit reports students’ scores on a scale that runs from 150-250, with higher scores indicating higher student performance. These scores can help you identify which students may have struggled with the assessment(s) and which students performed well. They also provide a way to measure students’ growth once they have taken two assessments in the series. 

Please note, if you see an asterisk next to a student's scaled score, this indicates that the student responded to less than 80% of the questions on an Assessment Series test. CommonLit’s scoring procedure treats not answering a question the same as getting a question wrong, so a student who skips a lot of questions may have an artificially low scaled score.

ℹ️ A students' scaled score also determines their student performance group. You can read more about performance groups in our other support article: How does CommonLit define Below & Approaching Grade Level, On Grade Level, and Above Grade Level?

How can scaled scores be compared between the Pre, Mid, and Post-Assessments?

Because scaled scores on different tests can be directly compared with one another, they allow you to measure student growth over time. That means that, even if one test is slightly easier or harder than another, students' scaled scores can be compared across those two tests. In other words, if a student’s score increases significantly from the Pre-Assessment to the Post-Assessment and the assessments were given under consistent conditions, that change can be more directly attributed to an increase in the student’s reading ability.

Student scores can also fluctuate slightly between each administration of an assessment because of a number of factors (e.g., their level of concentration on a given day), so small changes in student scores from the Pre- to the Post-Assessment are not indicative of either growth or decline in student ability. CommonLit’s data displays indicate what amount of growth is considered "significant" in each grade level.