percRank {CMO}R Documentation

A function to calculate Percent Ranks foreach entry of a given vector

Description

A percentile rank is typically defined as the proportion of scores in a distribution that a specific score is greater than or equal to. For example, a test score which is greater than 90% of the scores of people taking the test is said to be at the 90th percentile (percentile rank 90).

Usage

percRank(x)

Arguments

x The input vector

Details

Percentile ranks are commonly used to clarify the interpretation of scores on standardized tests. For the test theory, the percentile rank of a raw score is interpreted as the percentages of examinees in the norm group who scored below the score of interest (Crocker & Algina, 1986). Unlike a normal distribution of scores, which are bell shaped, the distribution of percentile ranks is uniform and is rectangular in shape.

Value

Returns a vector with percent ranks for each entry in the input vector

Author(s)

Christian Montel

References

Crocker, L., & Algina, J. (1986). Introduction to classical and modern test theory. New York: Harcourt Brace Jovanovich College Publishers.

http://en.wikipedia.org/wiki/Percentile_rank

Examples

#generate some data
d <- c(3,2,5,9,1,10,4,6,8,7)
percRank(d)

[Package CMO version 1.02 Index]