{{short description|Statistical principle about ratio of effects to causes}} {{for|the optimal allocation of resources|Pareto efficiency}}{{For|the related probability distribution|Pareto distribution}}{{specific|date=August 2022}} {{Use mdy dates|date=April 2026}} thumb|The Pareto principle may apply to fundraising, i.e., 20% of the donors contributing towards 80% of the total.
The '''Pareto principle''' (also known as the '''80:20 rule''', the '''law of the vital few''' and the '''principle of factor sparsity'''<ref name="NYT">{{cite news|url=https://www.nytimes.com/2008/03/03/business/03juran.html|title=Joseph Juran, 103, Pioneer in Quality Control, Dies|last1=Bunkley|first1=Nick|date=March 3, 2008|work=The New York Times|access-date=January 25, 2018|archive-url=https://web.archive.org/web/20170906182706/http://www.nytimes.com/2008/03/03/business/03juran.html|archive-date=September 6, 2017}}</ref><ref name=":0">{{cite journal|last1=Box|first1=George E.P.|last2=Meyer|first2=R. Daniel|date=1986|title=An Analysis for Unreplicated Fractional Factorials|journal=Technometrics|volume=28|issue=1|pages=11–18|doi=10.1080/00401706.1986.10488093}}</ref>) states that, for many outcomes, roughly 80% of consequences come from 20% of causes (the "vital few").<ref name="NYT"/>
In 1941, management consultant Joseph M. Juran developed the concept in the context of quality control and improvement after reading the works of Italian sociologist and economist Vilfredo Pareto, who wrote in 1906 about the 80:20 connection while teaching at the University of Lausanne.<ref>{{Cite book|last=Pareto|first=Vilfredo|title=Cours d'Économie Politique (in two volumes)|publisher=F. Rouge (Lausanne) & F. Pichon (Paris)|date=1896–1897}} [https://archive.org/details/fp-0148-1 Volume 1] [https://web.archive.org/web/20130531151249/http://www.institutcoppet.org/wp-content/uploads/2012/05/Cours-déconomie-politique-Tome-II-Vilfredo-Pareto.pdf Volume 2]</ref> In his first work, ''Cours d'économie politique'', Pareto showed that approximately 80% of the land in the Kingdom of Italy was owned by 20% of the population. The Pareto principle is only tangentially related to the concept of Pareto efficiency.
Mathematically, the 80:20 rule is associated with a power law distribution (also known as a Pareto distribution). In many natural phenomena certain features are distributed according to power law statistics.<ref name="auto1">{{cite journal|url=https://arxiv.org/PS_cache/cond-mat/pdf/0412/0412004v3.pdf|title=Power laws, Pareto Distributions, and Zipf's law|journal=Contemporary Physics|volume=46|issue=5|pages=323–351|last=Newman|first=MEJ|access-date=April 10, 2011|bibcode=2005ConPh..46..323N|year=2005|arxiv=cond-mat/0412004|doi=10.1080/00107510500052444|s2cid=202719165}}</ref> It is an adage of business management that "80% of sales come from 20% of clients."<ref>{{Cite news|last=Marshall|first=Perry|url=https://www.entrepreneur.com/article/229294|title=The 80/20 Rule of Sales: How to Find Your Best Customers|date=October 9, 2013|work=Entrepreneur|access-date=January 5, 2018|language=en}}</ref>
== History == In 1941, Joseph M. Juran, a Romanian-born American engineer, came across the work of Italian polymath Vilfredo Pareto. Pareto noted that approximately 80% of Italy's land was owned by 20% of the population.<ref name="auto">{{citation|title=''Translation of'' Manuale di economia politica ("Manual of political economy") |first1=Vilfredo|last1=Pareto|first2=Alfred N.|last2=Page|publisher=A.M. Kelley|year=1971|isbn=978-0-678-00881-2}}</ref><ref name="auto1"/> Juran applied the approximation that 80% of problems stem from 20% of the causes to the field of quality management. Later during his career, Juran preferred to describe this as "the vital few and the useful many", to dissuade from an interpretation of the principle as the contribution of the 80% being without value.<ref>{{Cite web|date=March 12, 2019|title=Pareto Principle (80/20 Rule) & Pareto Analysis Guide|url=https://www.juran.com/blog/a-guide-to-the-pareto-principle-80-20-rule-pareto-analysis/|access-date=February 27, 2021|website=Juran|language=en-US}}</ref>
== Mathematical explanation == The demonstration of the Pareto principle is explained by a large proportion of process variation being associated with a small proportion of process variables.<ref name=":0" /> This is a special case of the wider phenomenon of Pareto distributions. If the Pareto index '''α''', which is one of the parameters characterizing a Pareto distribution, is chosen as '''α''' = log<sub>4</sub>5 ≈ 1.16, then one has 80% of effects coming from 20% of causes.<ref>{{Citation |last=Dunford |first=R |title=The Pareto Principle |url=https://pearl.plymouth.ac.uk/bitstream/handle/10026.1/14054/TPSS-2014-Vol7n1_140-148Dunford.pdf |journal=The Plymouth Student Scientist |year=2014 |access-date=October 28, 2022 |archive-date=January 22, 2022 |archive-url=https://web.archive.org/web/20220122121809/https://pearl.plymouth.ac.uk/bitstream/handle/10026.1/14054/TPSS-2014-Vol7n1_140-148Dunford.pdf }}</ref>
The term 80:20 is only a shorthand for the general principle at work. In individual cases, the distribution could be nearer to 90:10 or 70:30. Note that there is no need for the two numbers to add up to the number 100, as they are measures of different things. The Pareto principle is an illustration of a "power law" relationship, which also occurs in phenomena such as bush fires and earthquakes.<ref>{{Citation |last=Bak |first=Per |title=How Nature Works: the science of self-organized criticality |page=89 |year=1999 |publisher=Springer |isbn=0-387-94791-4 |author-link=Per Bak}}</ref> Benoit Mandelbrot offered an explanation for this pattern in the field of economics and social science based on income dynamics in population. According to his reasoning, above a certain minimum income threshold, the probability of an individual's income increasing or decreasing by a fixed proportion (e.g., doubling) remains constant across all income levels. As a consequence, the ratio of individuals earning a given income x to those earning half that amount x/2 remains the same, regardless of the absolute value of x. This scale-invariant property is a defining feature of power-law distributions. Because it is self-similar over a wide range of magnitudes, it produces outcomes completely different from Normal or Gaussian distribution phenomena. The occurrence probability of rare extreme (or catastrophic) events showing power-law distribution may be of several orders of magnitude greater than that associated with other usual models, such as, e.g., Gaussian or exponential. This fact explains the frequent breakdowns of sophisticated financial instruments, which are modeled on the assumption that a Gaussian relationship is appropriate to something like stock price movements.<ref>{{Citation |last=Taleb |first=Nassim |title=The Black Swan |pages=229–252, 274–285 |year=2007 |author-link=Nassim Taleb |title-link=The Black Swan (Taleb book)}}</ref>
=== Derivation of ''α'' for the 80:20 rule ===
As an example, consider the Pareto distribution of wealth. The (Type 1) Pareto distribution is defined as:
<math display="block">p(x)= \begin{cases} \frac{\alpha\,x_\mathrm{m}^\alpha}{x^{\alpha+1}} & x \ge x_\mathrm{m}, \\ 0 & x < x_\mathrm{m}. \end{cases} </math>
where <math>x_m</math> is the scale parameter and <math>\alpha</math> is the shape parameter. The ''x'' variable will represent wealth in (e.g.) dollars, while ''p(x)dx'' will represent the fraction of the population with wealth between ''x'' and ''x+dx'' dollars. Defining ''N'' as the total population, the number of people owning between ''x'' and ''x+dx'' dollars will be <math>N p(x) dx</math> and they will own a total of <math>N x\,p(x) dx</math> dollars.
The total number of people with wealth between <math>x_a</math> and <math>x_b</math> dollars will then be:
:<math>N\int_{x_a}^{x_b} p(x)dx</math>
and they will be holding:
:<math>N \int_{x_a}^{x_b} x\,p(x)dx</math>
dollars of the total wealth. The total wealth is:
:<math>N \int_{x_m}^\infty x\,p(x)dx</math>
dollars. The 80% of the population on the low end of the wealth scale will be those owning between <math>x_m</math> and <math>x_o</math> dollars so that:
:<math>\frac{N\int_{x_m}^{x_o} p(x)dx}{N\int_{x_m}^\infty p(x)dx} = 1-\left(\frac{x_m}{x_o}\right)^\alpha= 0.8</math>
and if they hold 20% of the wealth then:
:<math>\frac{N\int_{x_m}^{x_o} x\,p(x)dx}{N\int_{x_m}^\infty x\,p(x)dx} = 1-\left(\frac{x_m}{x_o}\right)^{\alpha-1}= 0.2</math>
Solving the above two equations for <math>\alpha</math> and <math>x_o</math> yields <math>\alpha=\log_4(5)</math> and <math>x_o=4\, x_m</math>.
=== Gini coefficient and Hoover index === Using the "''A'':''B''" notation (for example, 0.8:0.2) and with ''A'' + ''B'' = 1, inequality measures like the Gini index (G) ''and'' the Hoover index (H) can be computed. In this case both are the same:
: <math>H=G=|2A-1|=|1-2B|=\frac{1}{2\alpha-1} </math>
which in the 80:20 case yields <math>\mathrm{G}\approx 0.756</math>
: <math>A:B = \left( \frac{1+H} 2 \right): \left( \frac{1-H} 2 \right)</math>
== Analysis == thumb|A Pareto analysis in a diagram showing which cause should be addressed first
Pareto analysis is a formal technique useful where many possible courses of action are competing for attention. In essence, the problem-solver estimates the benefit delivered by each action, then selects a number of the most effective actions that deliver a total benefit reasonably close to the maximal possible one.
Pareto analysis is a creative way of looking at causes of problems because it helps stimulate thinking and organize thoughts. However, it can be limited by its exclusion of possibly important problems which may be small initially, but will grow with time. It should be combined with other analytical tools such as failure mode and effects analysis and fault tree analysis for example.{{Citation needed|date=July 2009}}
This technique helps to identify the top portion of causes that need to be addressed to resolve the majority of problems. Once the predominant causes are identified, then tools like the Ishikawa diagram (also called Fish-bone Analysis) can be used to identify the root causes of the problems. While it is common to refer to Pareto as "80:20" rule, under the assumption that, in all situations, 20% of causes determine 80% of problems, this ratio is merely a convenient rule of thumb and is not, nor should it be considered, an immutable law of nature.
The application of the Pareto analysis in risk management allows management to focus on those risks that have the most impact on the project.<ref>David Litten, [http://www.pmhut.com/project-risk-and-risk-management Project Risk and Risk Management], ''Retrieved May 16, 2010''</ref>
Steps to identify the important causes using 80:20 rule:<ref>{{cite web|title=Pareto Analysis|url=http://erc.msh.org/quality/pstools/pspareto.cfm|accessdate=January 12, 2012|url-status=dead|archiveurl=https://web.archive.org/web/20120208180732/http://erc.msh.org/quality/pstools/pspareto.cfm|archivedate=February 8, 2012}}</ref>
# Form a frequency of occurrences as a percentage # Arrange the rows in decreasing order of importance of the causes (i.e., the most important cause first) # Add a cumulative percentage column to the table, then plot the information # Plot (#1) a curve with causes on ''x''- and cumulative percentage on ''y''-axis # Plot (#2) a bar graph with causes on ''x''- and percent frequency on ''y''-axis # Draw a horizontal dotted line at 80% from the ''y''-axis to intersect the curve. Then draw a vertical dotted line from the point of intersection to the ''x''-axis. The vertical dotted line separates the important causes (on the left) and trivial causes (on the right) # Explicitly review the chart to ensure that causes for at least 80% of the problems are captured
== Applications ==
=== Economics === Pareto's observation was in connection with population and wealth. Pareto noticed that approximately 80% of Italy's land was owned by 20% of the population.<ref name="auto"/> He then carried out surveys on a variety of other countries and found to his surprise that a similar distribution applied.{{citation needed|date=August 2022}}
A chart that demonstrated the effect appeared in the 1992 United Nations Development Program Report, which showed that the richest 20% of the world's population receives 82.7% of the world's income.<ref>{{citation|author=United Nations Development Program|title=1992 Human Development Report|year=1992|location=New York|publisher=Oxford University Press}}</ref> However, among nations, the Gini index shows that wealth distributions vary substantially around this norm.<ref>{{cite web|title=Poverty, Growth, and Inequality over the Next 50 Years|first=Evan|last=Hillebrand|publisher=FAO, United Nations – Economic and Social Development Department|date=June 2009|archive-url=https://web.archive.org/web/20171020065423/ftp://ftp.fao.org/docrep/fao/012/ak968e/ak968e00.pdf|archive-date=October 20, 2017|url-status=dead|url=ftp://ftp.fao.org/docrep/fao/012/ak968e/ak968e00.pdf}}</ref>
{| class="wikitable" |+ Distribution of world GDP, 1989<ref name="1992 Human Development Report, Chapter 3">{{citation|url=http://hdr.undp.org/en/reports/global/hdr1992/chapters/|title=Human Development Report 1992, Chapter 3|access-date=July 8, 2007}}</ref> |- ! scope="col" | Quintile of population ! scope="col" | Income |- | Richest 20% | 82.70% |- | Second 20% | 11.75% |- | Third 20% | 2.30% |- | Fourth 20% | 1.85% |- | Poorest 20% | 1.40% |}
The principle also holds within the tails of the distribution. The physicist Victor Yakovenko of the University of Maryland, College Park and AC Silva analyzed income data from the US Internal Revenue Service from 1983 to 2001 and found that the income distribution of the richest 1–3% of the population also follows Pareto's principle.<ref>{{Cite book|last1=Yakovenko|first1=Victor M.|chapter=Two-class Structure of Income Distribution in the USA: Exponential Bulk and Power-law Tail|date=2005|title=Econophysics of Wealth Distributions: Econophys-Kolkata I|pages=15–23|editor-last=Chatterjee|editor-first=Arnab|series=New Economic Windows|publisher=Springer Milan|language=en|doi=10.1007/88-470-0389-x_2|isbn=978-88-470-0389-7|last2=Silva|first2=A. Christian|editor2-last=Yarlagadda|editor2-first=Sudhakar|editor3-last=Chakrabarti|editor3-first=Bikas K.}}</ref>
In ''Talent: How to Identify Energizers, Creatives, and Winners Around the World'', economist Tyler Cowen and entrepreneur Daniel Gross suggest that the Pareto Principle can be applied to the role of the 20% most talented individuals in generating the majority of economic growth.<ref>Paris Aéroport, ''Paris Vous Aime Magazine'', No 13, avril-may-juin 2023, p. 71</ref> A supermarket industry maxim states that 20% of products provide 80% of profits.<ref name="goldberg19840904">{{Cite magazine |last=Goldberg |first=Cheryl J. |date=September 4, 1984 |title=Milk, Butter, Cheese, and PCs |url=https://books.google.com/books?id=vQDibG12bVcC&pg=PA204 |access-date=November 15, 2025 |magazine=PC |pages=204-215 |volume=3 |issue=17}}</ref> According to the ''New York Times'' in 1988, many video rental shops reported that 80% of revenue came from 20% of videotapes (although rarely rented classics such as ''Gone with the Wind'' must be stocked to appear to have a good selection).<ref name="kleinfield19880501">{{Cite news|url=https://www.nytimes.com/1988/05/01/business/a-tight-squeeze-at-video-stores.html?pagewanted=2|url-status=live|title=A Tight Squeeze at Video Stores|last=Kleinfield|first=N. R.|date=May 1, 1988|work=The New York Times|archive-url=https://web.archive.org/web/20150525080808/http://www.nytimes.com/1988/05/01/business/a-tight-squeeze-at-video-stores.html?pagewanted=2|archive-date=May 25, 2015|url-access=subscription|issn=0362-4331|access-date=March 7, 2024}}</ref>
=== Computing === In computer science the Pareto principle can be applied to optimization efforts.<ref name=optimization>{{citation|first1=M.|last1=Gen|first2=R.|last2=Cheng|title=Genetic Algorithms and Engineering Optimization|location=New York|publisher=Wiley|year=2002}}</ref> For example, Microsoft noted that by fixing the top 20% of the most-reported bugs, 80% of the related errors and crashes in a given system would be eliminated.<ref>{{citation|url=http://www.crn.com/news/security/18821726/microsofts-ceo-80-20-rule-applies-to-bugs-not-just-features.htm|title=Microsoft's CEO: 80–20 Rule Applies To Bugs, Not Just Features|first=Paula|last=Rooney|date=October 3, 2002|publisher=ChannelWeb}}</ref> Lowell Arthur expressed that "20% of the code has 80% of the errors. Find them, fix them!"<ref>Pressman, Roger S. (2010). Software Engineering: A Practitioner's Approach (7th ed.). Boston, Mass: McGraw-Hill, 2010. {{ISBN|978-0-07-337597-7}}.</ref>
=== Occupational health and safety === Occupational health and safety professionals use the Pareto principle to underline the importance of hazard prioritization. Assuming 20% of the hazards account for 80% of the injuries, and by categorizing hazards, safety professionals can target those 20% of the hazards that cause 80% of the injuries or accidents. Alternatively, if hazards are addressed in random order, a safety professional is more likely to fix one of the 80% of hazards that account only for some fraction of the remaining 20% of injuries.<ref>{{cite book |last=Woodcock |first=Kathryn |title=Safety Evaluation Techniques |year=2010 |publisher=Ryerson University |location=Toronto, ON |pages=86 |url=http://www.ryerson.ca/woodcock/ |archive-date=March 1, 2021 |access-date=January 14, 2012 |archive-url=https://web.archive.org/web/20210301094738/https://www.ryerson.ca/woodcock/ |url-status=dead }}</ref>
Aside from ensuring efficient accident prevention practices, the Pareto principle also ensures hazards are addressed in an economical order, because the technique ensures the utilized resources are best used to prevent the most accidents.<ref name=USCG001>{{cite web|title=Introduction to Risk-based Decision-Making |url= http://www.uscg.mil/hq/cg5/cg5211/docs/RBDM_Files/PDF/RBDM_Guidelines/Volume%202/Volume%202-Chapter%206.pdf |work=USCG Safety Program |publisher= United States Coast Guard |access-date= January 14, 2012}}</ref>
=== Engineering and quality control === The Pareto principle provides the basis for the Pareto chart, one of the key tools used in total quality control and Six Sigma techniques. The Pareto principle serves as a baseline for ABC-analysis and XYZ-analysis, widely used in logistics and procurement for the purpose of optimizing stock of goods, as well as costs of keeping and replenishing that stock.<ref>{{harvtxt|Rushton|Oxley|Croucher|2000}}, pp. 107–108.</ref> In engineering control theory, such as for electromechanical energy converters, the 80:20 principle applies to optimization efforts.<ref name="optimization" />
The remarkable success of statistically based searches for root causes is based upon a combination of an empirical principle and mathematical logic. The empirical principle is usually known as the Pareto principle.<ref name=" Juran "> Juran, Joseph M., Frank M. Gryna, and Richard S. Bingham. Quality control handbook. Vol. 3. New York: McGraw-Hill, 1974.</ref> With regard to variation causality, this principle states that there is a non-random distribution of the slopes of the numerous (theoretically infinite) terms in the general equation.
All of the terms are independent of each other by definition. Interdependent factors appear as multiplication terms. The Pareto principle states that the effect of the dominant term is very much greater than the second-largest effect term, which in turn is very much greater than the third, and so on.<ref name=" Shainin "> Shainin, Richard D. “Strategies for Technical Problem Solving.” 1992, Quality Engineering, 5:3, 433-448</ref> There is no explanation for this phenomenon; that is why we refer to it as an empirical principle.
The mathematical logic is known as the square-root-of-the-sum-of-the-squares axiom. This states that the variation caused by the steepest slope must be squared, and then the result added to the square of the variation caused by the second-steepest slope, and so on. The total observed variation is then the square root of the total sum of the variation caused by individual slopes squared. This derives from the probability density function for multiple variables or the multivariate distribution (we are treating each term as an independent variable).
The combination of the Pareto principle and the square-root-of-the-sum-of-the-squares axiom means that the strongest term in the general equation totally dominates the observed variation of effect. Thus, the strongest term will dominate the data collected for hypothesis testing.
In the systems science discipline, Joshua M. Epstein and Robert Axtell created an agent-based simulation model called Sugarscape, from a decentralized modeling approach, based on individual behavior rules defined for each agent in the economy. Wealth distribution and Pareto's 80:20 principle emerged in their results, which suggests the principle is a collective consequence of these individual rules.<ref>{{Citation|last1=Epstein|first1=Joshua|title=Growing Artificial Societies: Social Science from the Bottom-Up|url=https://books.google.com/books?id=xXvelSs2caQC|page=208|year=1996|publisher=MIT Press|isbn=0-262-55025-3|last2=Axtell|first2=Robert}} </ref>
=== Health and social outcomes === In 2009, the Agency for Healthcare Research and Quality said 20% of patients incurred 80% of healthcare expenses due to chronic conditions.<ref>{{cite web|url=http://www.projo.com/opinion/contributors/content/CT_weinberg27_07-27-09_HQF0P1E_v15.3f89889.html|title=Myrl Weinberg: In health-care reform, the 20-80 solution|last1=Weinberg|first1=Myrl| website=The Providence Journal|date=July 27, 2009|archive-url=https://web.archive.org/web/20090802002952/http://www.projo.com/opinion/contributors/content/CT_weinberg27_07-27-09_HQF0P1E_v15.3f89889.html|archive-date=August 2, 2009}}</ref> A 2021 analysis showed unequal distribution of healthcare costs, with older patients and those with poorer health incurring more costs.<ref>{{cite web |last1=Sawyer |last2=Claxton |first1=Bradley |first2=Gary |title=How do health expenditures vary across the population? |url=https://www.healthsystemtracker.org/chart-collection/health-expenditures-vary-across-population/#item-discussion-of-health-spending-often-focus-on-averages-but-a-small-share-of-the-population-incurs-most-of-the-cost_2016 |website=Peterson-Kaiser Health System Tracker |publisher=Peterson Center on Healthcare and the Kaiser Family Foundation |access-date=March 13, 2019}}</ref> The 80:20 rule has been proposed as a rule of thumb for the infection distribution in superspreading events.<ref>{{cite journal|last1=Galvani|first1=Alison P.|last2=May|first2=Robert M.|year=2005|title=Epidemiology: Dimensions of superspreading|journal=Nature|volume=438|issue=7066|pages=293–295|doi=10.1038/438293a|pmid=16292292|bibcode=2005Natur.438..293G|pmc=7095140}}</ref><ref name="Lloyd-Smith JO 2005" /> However, the degree of infectiousness has been found to be distributed continuously in the population.<ref name="Lloyd-Smith JO 2005">{{cite journal|last1=Lloyd-Smith|first1=JO|last2=Schreiber|first2=SJ|last3=Kopp|first3=PE|last4=Getz|first4=WM|year=2005|title=Superspreading and the effect of individual variation on disease emergence|journal=Nature|volume=438|issue=7066|pages=355–359|doi=10.1038/nature04153|pmid=16292310|bibcode=2005Natur.438..355L|pmc=7094981}}</ref> In epidemics with super-spreading, the majority of individuals infect relatively few secondary contacts.
=== Dating and relationships === In dating and relationships, the Pareto principle is applied mainly by incel communities, who theorize that 20% of the most attractive men have monopolized 80% of women as romantic partners.<ref>{{cite journal |last1=RAN Practitioners|date=June 17-18, 2021|title=The Incel Phenomenon: Exploring Internal and External Issues Around Involuntary Celibates|url=https://home-affairs.ec.europa.eu/system/files/2021-08/ran_cn_incel_phenomenon_20210803_en.pdf|journal=The Incel Phenomenon|volume= |issue= |publisher=Radicalisation Awareness Network|pages=2 |doi= |access-date=April 3, 2026}}</ref><ref>{{cite journal|last1=Woodward|first1=Alexandra|date=December 2021|title=Incels: Inside the World of Involuntary Celibates|url=https://archive.nyu.edu/bitstream/2451/63962/3/Incels_%20Inside%20the%20World%20of%20Involuntary%20Celibates%20-%20Alexandra%20Woodward.pdf|journal=Center for Global Affairs|volume= |issue= |publisher=NYU School of Professional Studies|pages=5 |doi= |access-date=April 3, 2026}}</ref> This top 20% of men are referred to as "Chads." They are described as being usually good looking, tall, muscular, and wealthy, or otherwise have high status. Incels assert that these attractiveness factors are based on biological determinism. According to this ideology, men who do not fit this top 20% are destined to a life of loneliness and will never have any opportunities to find a sexual partner or a meaningful relationship, due to this statistical unlikelihood. The vast majority of self-described incels (over two-thirds) agree with the 80/20 rule, in this context.<ref>{{cite journal |last1=Costello |first1=William |last2=Whittaker |first2=Joe |last3=Thomas |first3=Andrew G. |date=April 23, 2024 |title=The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates |url=https://labs.la.utexas.edu/buss/files/2025/05/The-Dual-Pathways-Hypothesis-of-Incel-Harm.pdf |journal=Archives of Sexual Behavior |volume= |issue= |publisher=Springer |pages= |doi= |access-date=April 3, 2026}}</ref>
== See also == * {{anl|1% rule}} * {{anl|10/90 gap}} * {{anl|Ninety–ninety rule}} * {{anl|Sturgeon's law}}
== References == {{Reflist}}
== Further reading == * {{Citation |last=Bookstein |first=Abraham |year=1990 |title=Informetric distributions, part I: Unified overview |journal=Journal of the American Society for Information Science |volume=41 |issue= 5|pages=368–375 |doi=10.1002/(SICI)1097-4571(199007)41:5<368::AID-ASI8>3.0.CO;2-C }} * {{Citation |author1=Klass, O. S. |author2=Biham, O. |author3=Levy, M. |author4=Malcai, O. |author5=Soloman, S. |year=2006 |title=The Forbes 400 and the Pareto wealth distribution |journal=Economics Letters |volume=90 |issue=2 |pages=290–295 |doi=10.1016/j.econlet.2005.08.020 }} * {{Citation |title=Living the 80/20 Way: Work Less, Worry Less, Succeed More, Enjoy More |last=Koch |first=R. |year=2004 |publisher=Nicholas Brealey Publishing |location=London |isbn=1-85788-331-4 }} * {{Citation |last=Reed |first=W. J. |year=2001 |title=The Pareto, Zipf and other power laws |journal=Economics Letters |volume=74 |issue=1 |pages=15–19 |doi=10.1016/S0165-1765(01)00524-9 }} * {{Citation |doi=10.1016/0094-1190(80)90043-1 |author1=Rosen, K. T. |author2=Resnick, M. |year=1980 |title=The size distribution of cities: an examination of the Pareto law and primacy |journal=Journal of Urban Economics |volume=8 |issue= 2|pages=165–186 |url= https://escholarship.org/uc/item/9tt5c711}} * {{citation |title=The handbook of logistics and distribution management |last1=Rushton |first1=A. |last2=Oxley|first2= J.|last3= Croucher|first3= P. |year=2000 |edition=2nd |publisher=Kogan Page |location=London |isbn=978-0-7494-3365-9 }}.
== External links == {{Commons category}}
* [https://www.fichansraj.org/post/pareto-rule-of-causes-and-consequences Pareto Principle: Rule of causes and consequences] * [https://www.paretorule.cf/?m=1 ParetoRule.cf : Pareto Rule] {{Webarchive|url=https://web.archive.org/web/20181202202708/https://www.paretorule.cf/?m=1 |date=December 2, 2018 }} * [https://www.paretorule.cf/2018/12/the-pareto-Rule.html?m=1 ParetoRule.cf : The Pareto Rule] {{Webarchive|url=https://web.archive.org/web/20181202202706/https://www.paretorule.cf/2018/12/the-pareto-Rule.html?m=1 |date=December 2, 2018 }} * [http://management.about.com/cs/generalmanagement/a/Pareto081202.htm About.com: Pareto's Principle] {{Webarchive|url=https://web.archive.org/web/20090213165607/http://management.about.com/cs/generalmanagement/a/Pareto081202.htm |date=February 13, 2009 }} * [https://www.simplypsychology.org/pareto-principle.html Simply Psychology: Pareto Principle (The 80-20 Rule): Examples & More] * [https://i2notes.com/2026/02/12/the-pareto-principle-80-20-rule/ The Pareto Principle (80/20 Rule) Practical strategies inside]
{{Vilfredo Pareto}} {{Authority control}}
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