Percentiles
What are percentiles?
The percentiles of a distribution are a set of 101 numbers that break data from a continuous variable into 100 equal parts.
When should you use percentiles?
Use percentiles as you would use quantiles for any integer percentage of the data. For example, if you administered an exam to your students and you wanted to find the score at which below 80% of the students scored, you would calculate the 80th percentile.
How do you calculate percentiles?
Use the formula for quantiles to calculate percentiles.
Statistical software, like JMP, can also calculate percentiles. Different software might use different formulas. Be sure to check the software’s documentation to find which formula is used.
Examples of percentiles
For the cereal calories data, you can see some common quantiles, including some percentiles, in the figure below.
As another example, examine some percentiles for the data in the Univariate Statistics Data. You can visualize the quantiles using the quantile box plot and see the value of some quantiles, including some percentiles, in the Quantiles report.
