Concept

Percentile

For statistical data on a population, a percentile represents the percentage of the total data that falls below a given data point. Consider the results of a state-wide standardized test; a graph of the scores from least to greatest might take the following shape.
If a student named Jane scored 80% on this test, her score was better than 96% of the other scores recorded in the state. Therefore, Jane's score was at the 96^(th) percentile of the test scores. Compare some other test scores with the rest of the data using the graph below.

Extra

Percentiles in Normally Distributed Data

Normally distributed data is commonly divided into bands, or subsections, that have the width of one standard deviation σ.

Given that half the population is to the left of the median μ, and the first band to the right of the median contains 34.1% of the population, it can be stated that the 84th percentile for normally distributed data is μ + σ.

Exercises