World Library  
Flag as Inappropriate
Email this Article

Percentage point

Article Id: WHEBN0001969007
Reproduction Date:

Title: Percentage point  
Author: World Heritage Encyclopedia
Language: English
Subject: Miramichi (electoral district), Simcoe North, Beauce (electoral district), Halton (electoral district), Portneuf—Jacques-Cartier
Collection: Mathematical Terminology, Statistical Terminology
Publisher: World Heritage Encyclopedia

Percentage point

A percentage point (pp) is the unit for the arithmetic difference of two percentages, e.g. going from 40% to 44% is a 4 percentage point increase.[1] In the literature, the percentage point unit is usually either written out,[2] or abbreviated as pp, p.p. or %.[3] Consider the following hypothetical example: In 1980, 40 percent of the population smoked, and in 1990 only 30 percent smoked. One can thus say that from 1980 to 1990, the incidence of smoking decreased by 10 percentage points although smoking did not decrease by 10 percent (actually it decreased by 25 percent) – percentages indicate ratios, not differences.

Percentage point differences are one way to express a risk or probability. Consider a drug that cures a given disease in 70 percent of all cases, while without the drug, the disease heals spontaneously in only 50 percent of cases. The drug reduces absolute risk by 20 percentage points. Alternatives may be more meaningful to consumers of statistics. The such as the reciprocal (also known as the number needed to treat (NNT)). In this case, the reciprocal transform of the percentage point difference would be 1 / (20%) = 1 / 0.20 = 5, i.e., if 5 patients are treated with the drug, one could expect to heal one more case of the disease than would have occurred in the absence of the drug.

For measurements with percentage as unit, like growth, yield, or ejection fraction, the standard deviation will have percentage points as unit. Mistakenly using percentage as the unit for the standard deviation is confusing since percentage is also used as a unit for the relative standard deviation, i.e. the standard deviation divided by the average value (Coefficient of Variation).

Related units


  1. ^ Brechner, Robert (2008). Contemporary Mathematics for Business and Consumers, Brief Edition. Cengage Learning. p. 190. Retrieved 7 May 2015. 
  2. ^ Wickham, Kathleen (2003). Math Tools for Journalists. Cengage Learning. p. 30. Retrieved 7 May 2015. 
  3. ^ Weisstein, Eric. "Percentage Point.". MathWorld. Retrieved 8 October 2015. 
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.