Percentile rank

Occasionally the percentile rank of a score is mistakenly defined as the percentage of scores lower than or equal to it[citation needed], but that would require a different computation, one with the 0.5 × F term deleted.

Typically percentile ranks are only computed for scores in the distribution but, as the figure illustrates, percentile ranks can also be computed for scores whose frequency is zero.

In educational measurement, a range of percentile ranks, often appearing on a score report, shows the range within which the test taker's "true" percentile rank probably occurs.

[2] Percentile ranks are commonly used to clarify the interpretation of scores on standardized tests.

Percentile rank 30 is closer on the bell curve to 40 than it is to 20.