What Do Standardized Test Scores, and Percentiles, Mean?

Often when schools do standardized testing, they report the scores in percentiles.

Percentiles are not the same thing as percentages (percents), even though they sound like they should be. Percentages are what most teachers use when grading their student’s work.Percentiles are numbers that show how a child compares to others. They are used on standardized tests that have been given to a large group of students before—this is the norm group.

If your child takes a regular test in the classroom, the chances are pretty good the teacher will give her a grade based on how many points she missed out of the total number of possible points. For example, if there are 100 points on the test and your daughter misses 15 points, her score will be 85 percent. This is calculated by dividing the points earned (85) by the number of possible points (100) and then multiplying that answer by 100. Note that this score does not tell you how well she did compared to other students.

Standardized tests, in contrast to regular tests, are given to large groups of students at various age levels. Students who take the same test later have their scores compared to a large norm group made up of students who took the test before. A percentile compares your child’s performance to these students who are the same age. An 85th percentile score means that your son scored better than 85 percent of the students in that large comparison group. Another way to think about it is this: If you had 100 students in the comparison group who are the same age, your child did better than 85 of them. This would be a very high percentile score.

When some parents see that their child’s result is in the 50th percentile, they think their child did poorly on the test. Instead, this means the student is right where you expect she should be! This is average. Above the 50th percentile is above average. Below the 50th percentile is below average.

Another score you are likely to see is the “Grade Equivalent” score. I will write about that in my blog post next week, here at SchoolFamily.com.

Parents, teachers, and students worry a lot about these tests and percentile results, so it is important to understand what the scores mean when you receive them.

For ideas for how to help your child manage the stress of taking standardized tests, read my earlier blog post about high stakes testing.