Testing 101: How to Understand and Use Percentile Ranks

Most car insurance companies offer high school students a discount if the student can prove he or she is academically “above average.” The standard to qualify for the discount is a “B” average on the student’s transcript. The creation and maintenance of a high school transcript is one of the features and benefits of our popular Diploma Program. But, what if you’re not in a diploma program that results in a transcript? Many insurance companies will accept the results of an achievement test. The score they use to determine if a student is above average is the National Percentile Rank. A percentile rank score of 60 or above is considered above average.

The National Percentile Rank score (NP) typically follows the Raw Score (RS) as you look across the page of an achievement test report from left to right. Once again it will be helpful for you to reference our sample report (click to view) as I explain this score. On our sample report, the first subtest is Reading. Across from this test title is 20/34. This is the Raw Score. The score next to this is 34 which is the National Percentile Rank score. It is right below the letters NP which stand for National Percentile.

The National Percentile score ranks raw scores from highest to lowest and shows where an individual’s raw score falls in comparison. The lowest score that is reported is 1; the highest is 99. Here’s how the scale breaks down:

1- 4: lowest
5-10: low
11-22: well below average
23-40: slightly below average
41-59: average
60-77: slightly above average
78-89: well above average
90-95: high
96-99: highest

A common misconception confuses percentile ranks with percentages. The confusion shows up in the question, “Why, if I got a perfect score answering every question correctly, isn’t my percentile rank a 100?”

Again, a percentile is a comparison of one particular student’s performance to a sampling of other students. Thinking of this score in terms of a bell-shaped curve helps to visualize it. The 34 on the sample report tells us that this student’s score for this subtest was better than 34 percent of students nationwide who took the same test. A score of 34 indicates the student’s performance was slightly below average. “Average” is defined as a score falling between (and including) 41 and 59, the center of the “bell.”

The value of a national percentile rank is that it is based on a national sampling of student performance rather than simply a smaller and local one. Smaller samplings may reflect state or regional populations. They are often less helpful and can even be misleading. In other words, consider a student whose intelligence and performance is in the “average range.” Compare his or her test performance to a group of “high-octane, over-achiever types” and where do you think his percentile rank will be? Near or at the bottom. Likewise, compare him or her to a group of students for whom education is unimportant and who could care less about learning, and the percentile rank will likely be near the top. I say likely because some “under achievers” are really smart but are bored by the instructional setting in which they find themselves. The basic principle is, the larger the number of students your student is compared to, the more realistic the picture the test will present of your student’s performance and standing.

In my next article I’ll comment on Normal Curve Equivalents and Stanines. I know, sounds real exciting…but it’s helpful to know what they mean.

Thanks for Reading,

Curt Bumcrot, MRE

• Our test dates for Washington are now available, including an upcoming test on Thursday, August 19th at the Firmly Planted Resource Center.
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