Percentile Rank

Percentile rank tells you how a score compares with a group by measuring the share of values that fall below it. If 18 out of 25 scores are lower than a student’s score, then 18/25 of the group is below that score, and multiplying by 100 turns that fraction into a percentage. This works because percentile rank is just a relative position in a data set expressed as a percent.

Use this when you want to describe how a test score, height, weight, or other measurement compares to a collection of results. It is especially useful in exams, psychology, health data, and any ranking situation where you want to know what percent of the group a value outperforms.

• Using the number of scores equal to the value instead of only the scores below it
• Forgetting to divide by the total number of values before multiplying by 100
• Confusing percentile rank with the actual score percentile label, which may be rounded or estimated differently