How to calculate percentile ranks

Written by david ferris
  • Share
  • Tweet
  • Share
  • Pin
  • Email
How to calculate percentile ranks
Use percentiles to evaluate test performance. (cholesteral test supplies image by Pix by Marti from Fotolia.com)

Percentile ranking is a valuable statistical tool with many applications. Percentiles are employed in evaluating standardised tests, measuring group performance and evaluating distribution of wealth across a population. On tests, a percentile is the percentage of scores less than a given score. Percentiles are useful for evaluating things such as test scores because they convert raw data into a simpler form that is easier to understand.

Skill level:
Moderate

Other People Are Reading

Instructions

  1. 1

    Organise the data in numerical order from lowest to highest, where the rank of each datum represents "i." For example, the third-lowest score will be "i3" when plugged into the formula.

  2. 2

    Calculate "n," the number of observations. For example, in a classroom test, it would be the number of test-takers.

  3. 3

    Compute percentile using the formula P = (100(i - 0.5))/n, where "i" equals the rank from Step 1 and "n" is the total number of observations. For example, on a seven-person test, to figure out the percentile for the third-lowest score, you would calculate (100(3-.5))/7, which equals 35.7, or the 35.7 percentile.

Don't Miss

Resources

Filter:
  • All types
  • Articles
  • Slideshows
  • Videos
Sort:
  • Most relevant
  • Most popular
  • Most recent

No articles available

No slideshows available

No videos available

By using the eHow.co.uk site, you consent to the use of cookies. For more information, please see our Cookie policy.