Verifiability, not truth

The reliability of Wikipedia concerns the validity, verifiability, and veracity of Wikipedia and its user-generated editing model, particularly its English-language edition. It is written and edited by volunteer editors who generate online content with the editorial oversight of other volunteer editors via community-generated policies and guidelines. Wikipedia carries the general disclaimer that it can be " edited by anyone at any time" and maintains an inclusion threshold of " verifiability, not truth". This editing model is highly concentrated, as 77% of all articles are written by 1% of its editors, a majority of whom have chosen to remain anonymous. The reliability of the project has been tested statistically through comparative review, analysis of the historical patterns, and strengths and weaknesses inherent in its editing process. The online encyclopedia has been criticized for its factual reliability, principally regarding its content, presentation, and editorial processes. Studies and surveys attempting to gauge the reliability of Wikipedia have mixed results, with findings varied and inconsistent. Wikipedia's reliability was frequently criticized in the 2000s but has improved over time; it has been generally praised in the late 2010s and early 2020s.

Select assessments of its reliability have examined how quickly vandalism—content perceived by editors to constitute false or misleading information—is removed. Two years after the project was started, in 2003, an IBM study found that "vandalism is usually repaired extremely quickly—so quickly that most users will never see its effects". The inclusion of false or fabricated content has, at times, lasted for years on Wikipedia due to its volunteer editorship. Its editing model facilitates multiple systemic biases: namely, selection bias, inclusion bias, participation bias, and group-think bias. The majority of the encyclopedia is written by male editors, leading to a gender bias in coverage and the make up of the editing community has prompted concerns about racial bias, spin bias, corporate bias, and national bias, among others. An ideological bias on Wikipedia has also been identified on both conscious and subconscious levels. A series of studies from Harvard Business School in 2012 and 2014 found Wikipedia "significantly more biased" than ''Encyclopædia Britannica'' but attributed the finding more to the length of the online encyclopedia as opposed to slanted editing.

The prevalence of non-neutral or conflict-of-interest editing and the use of Wikipedia for "revenge editing" has attracted publicity for inserting false, biased, or defamatory content into articles, especially biographies of living people. Articles on less technical subjects, such as the social sciences, humanities, and culture, have been known to deal with misinformation cycles, cognitive biases, coverage discrepancies, and editor disputes. The online encyclopedia does not guarantee the validity of its information. It is seen as a valuable "starting point" for researchers when they pass over content to examine the listed references, citations, and sources. Academics suggest reviewing reliable sources when assessing the quality of articles.

Its coverage of medical and scientific articles such as pathology, toxicology, oncology, pharmaceuticals, and psychiatry were compared to professional and peer-reviewed sources in a 2005 ''Nature'' study''.'' The study (which was not in itself peer-reviewed) was cited in many news articles such as this: A year later ''Encyclopædia Britannica'' disputed the ''Nature'' study, whose authors, in turn, replied with a further rebuttal. Concerns regarding readability and the overuse of technical language were raised in studies published by the American Society of Clinical Oncology (2011), ''Psychological Medicine'' (2012), and '' European Journal of Gastroenterology and Hepatology'' (2014). Wikipedia's popularity, mass readership, and free accessibility has led the encyclopedia to command a substantial second-hand cognitive authority across the world.

Wikipedia editing model

Wikipedia allows for anonymous editing; contributors are not required to provide any identification or an email address. A 2007 study at Dartmouth College of the English Wikipedia noted that, contrary to usual social expectations, anonymous editors were some of Wikipedia's most productive contributors of valid content. The Dartmouth study was criticized by John Timmer of the ''Ars Technica'' website for its methodological shortcomings.

Wikipedia trusts the same community to self-regulate and become more proficient at quality control. Wikipedia has harnessed the work of millions of people to produce the world's largest knowledge-based site along with software to support it, resulting in more than nineteen million articles written, across more than 280 different language versions, in fewer than twelve years. For this reason, there has been considerable interest in the project both academically and from diverse fields such as information technology, business, project management, knowledge acquisition, software programming, other collaborative projects and sociology, to explore whether the Wikipedia model can produce quality results, what collaboration in this way can reveal about people and whether the scale of involvement can overcome the obstacles of individual limitations and poor editorship which would otherwise arise.

Fact-checking

Fact-checking of Wikipedia is the process through which Wikipedia editors perform fact-checking of content published in Wikipedia, while fact-checking using Wikipedia is the use of Wikipedia for fact-checking other publications. The broader topic of fact checking in the context of Wikipedia also includes the cultural discussion of the place of Wikipedia in fact-checking. Major platforms including YouTube and Facebook use Wikipedia's content to confirm the accuracy of information in their own media collections. Seeking public trust is a major part of Wikipedia's publication philosophy.

Assessments

Criteria for evaluating reliability

The reliability of Wikipedia articles can be measured by the following criteria:
* Accuracy of information provided within articles
* Appropriateness of the images provided with the article
* Appropriateness of the style and focus of the articles
* Susceptibility to, and exclusion and removal of, false information
* Comprehensiveness, scope and coverage within articles and in the range of articles
* Identification of reputable third-party sources as citations
* Verifiability of statements by respected sources
* Stability of the articles
* Susceptibility to editorial and systemic bias
* Quality of writing

Several "market-oriented" extrinsic measures demonstrate that large audiences trust Wikipedia in one way or another. For instance, "50 percent of Sphysicians report that they've consulted ... ikipediafor information on health conditions", according to a report from IMS Institute for Healthcare Informatics.

Comparative studies

On October 24, 2005, British newspaper ''The Guardian'' published a story titled "Can you trust Wikipedia?" in which a panel of experts were asked to review seven entries related to their fields, giving each article reviewed a number designation from 0 to 10. Most of these reviewed articles received marks between 5 and 8. The most common critiques were poor prose, or ease-of-reading issues (three mentions), omissions or inaccuracies, often small but including key omissions in some articles (three mentions), and poor balance, with less important areas being given more attention and vice versa (one mention). The most common praises were factually sound and correct, no glaring inaccuracies (four mentions), and much useful information, including well-selected links, making it possible to "access much information quickly" (three mentions).

In December 2005, the journal ''Nature'' published results of an attempted blind study seeking reviewer evaluations of the accuracy of a small subset of articles from Wikipedia and ''Encyclopædia Britannica''. The non-peer-reviewed study was based on ''Nature''s selection of 42 articles on scientific topics, including biographies of well-known scientists. The articles were compared for accuracy by anonymous academic reviewers, a customary practice for journal article reviews. Based on their reviews, on average the Wikipedia articles were described as containing 4 errors or omissions, while the ''Britannica'' articles contained 3. Only 4 serious errors were found in Wikipedia, and 4 in ''Britannica''. The study concluded that "Wikipedia comes close to ''Britannica'' in terms of the accuracy of its science entries", although Wikipedia's articles were often "poorly structured".

''Encyclopædia Britannica'' expressed concerns, leading ''Nature'' to release further documentation of its survey method. Based on this additional information, ''Encyclopædia Britannica'' denied the validity of the ''Nature'' study, stating that it was "fatally flawed". Among ''Britannica''s criticisms were that excerpts rather than the full texts of some of their articles were used, that some of the extracts were compilations that included articles written for the youth version, that ''Nature'' did not check the factual assertions of its reviewers, and that many points the reviewers labeled as errors were differences of editorial opinion. ''Britannica'' further stated that "While the heading proclaimed that 'Wikipedia comes close to ''Britannica'' in terms of the accuracy of its science entries,' the numbers buried deep in the body of the article said precisely the opposite: Wikipedia in fact had a third more inaccuracies than ''Britannica''. (As we demonstrate below, 's research grossly exaggerated 's inaccuracies, so we cite this figure only to point out the slanted way in which the numbers were presented.)" ''Nature'' acknowledged the compiled nature of some of the ''Britannica'' extracts, but denied that this invalidated the conclusions of the study. ''Encyclopædia Britannica'' also argued that a breakdown of the errors indicated that the mistakes in Wikipedia were more often the inclusion of incorrect facts, while the mistakes in ''Britannica'' were "errors of omission", making "''Britannica'' far more accurate than ''Wikipedia'', according to the figures". ''Nature'' has since rejected the ''Britannica'' response, stating that any errors on the part of its reviewers were not biased in favor of either encyclopedia, that in some cases it used excerpts of articles from both encyclopedias, and that ''Britannica'' did not share particular concerns with ''Nature'' before publishing its "open letter" rebuttal.

The point-for-point disagreement between these two parties that addressed the compilation/text excerpting and very small sample size issues—argued to bias the outcome in favor of Wikipedia, versus a comprehensive, full article, large sample size study favoring the quality-controlled format of ''Britannica''—have been echoed in online discussions, including of articles citing the ''Nature'' study, e.g., where a "flawed study design" for manual selection of articles/article portions, the lack of study "statistical power" in its comparing 40 articles from over 100,000 ''Britannica'' and over 1 million English Wikipedia articles, and the absence of any study statistical analyses (e.g., reported confidence intervals for study results) has also been noted.

In June 2006, Roy Rosenzweig, a professor specializing in American history, published a comparison of the Wikipedia biographies of 25 Americans to the corresponding biographies found on Encarta and ''American National Biography Online''. He wrote that Wikipedia is "surprisingly accurate in reporting names, dates, and events in U.S. history" and described some of the errors as "widely held but inaccurate beliefs". However, he stated that Wikipedia often fails to distinguish important from trivial details, and does not provide the best references. He also complained about Wikipedia's lack of "persuasive analysis and interpretations, and clear and engaging prose". (Center for History and New Media)

A web-based survey conducted from December 2005 to May 2006 by Larry Press, a professor of Information Systems at California State University at Dominguez Hills, assessed the "accuracy and completeness of Wikipedia articles". Fifty people accepted an invitation to assess an article. Of the fifty, seventy-six percent (76%) agreed or strongly agreed that the Wikipedia article was accurate, and forty-six percent (46%) agreed or strongly agreed that it was complete. Eighteen people compared the article they reviewed to the article on the same topic in the ''Encyclopædia Britannica''. Opinions on accuracy were almost equal between the two encyclopedias (6 favoring ''Britannica'', 7 favoring Wikipedia, 5 stating they were equal), and eleven of the eighteen (61%) found Wikipedia somewhat or substantially more complete, compared to seven of the eighteen (39%) for ''Britannica''. The survey did not attempt a random selection of the participants, and it is not clear how the participants were invited.

The German computing magazine ''c't'' performed a comparison of '' Brockhaus Multimedial'', ''Microsoft Encarta'', and the German Wikipedia in October 2004: Experts evaluated 66 articles in various fields. In overall score, Wikipedia was rated 3.6 out of 5 points (B-). A second test by ''c't'' in February 2007 used 150 search terms, of which 56 were closely evaluated, to compare four digital encyclopedias: Bertelsmann Enzyklopädie 2007, Brockhaus Multimedial premium 2007, Encarta 2007 Enzyklopädie and Wikipedia. It concluded: "We did not find more errors in the texts of the free encyclopedia than in those of its commercial competitors."

Viewing Wikipedia as fitting the economists' definition of a perfectly competitive marketplace of ideas, George Bragues (University of Guelph-Humber), examined Wikipedia's articles on seven top Western philosophers: Aristotle, Plato, Immanuel Kant, René Descartes, Georg Wilhelm Friedrich Hegel, Thomas Aquinas, and John Locke. Wikipedia's articles were compared to a consensus list of themes culled from four reference works in philosophy. Bragues found that, on average, Wikipedia's articles only covered 52% of consensus themes. No errors were found, though there were significant omissions.

'' PC Pro'' magazine (August 2007) asked experts to compare four articles (a small sample) in their scientific fields between Wikipedia, ''Britannica'' and Encarta. In each case Wikipedia was described as "largely sound", "well handled", "performs well", "good for the bare facts" and "broadly accurate". One article had "a marked deterioration towards the end" while another had "clearer and more elegant" writing, a third was assessed as less well written but better detailed than its competitors, and a fourth was "of more benefit to the serious student than its Encarta or Britannica equivalents". No serious errors were noted in Wikipedia articles, whereas serious errors were noted in one Encarta and one ''Britannica'' article.''PC Pro'' magazine, August 2007, p. 136, "Wikipedia Uncovered".

In October 2007, the Australian magazine ''PC Authority'' published a feature article on the accuracy of Wikipedia. The article compared Wikipedia's content to other popular online encyclopedias, namely '' Britannica'' and Encarta. The magazine asked experts to evaluate articles pertaining to their field. A total of four articles were reviewed by three experts. Wikipedia was comparable to the other encyclopedias, topping the chemistry category.

In December 2007, German magazine ''Stern'' published the results of a comparison between the German Wikipedia and the online version of the 15-volume edition of ''Brockhaus Enzyklopädie''. The test was commissioned to a research institute (Cologne-based ''WIND GmbH''), whose analysts assessed 50 articles from each encyclopedia (covering politics, business, sports, science, culture, entertainment, geography, medicine, history and religion) on four criteria (accuracy, completeness, timeliness and clarity), and judged Wikipedia articles to be more accurate on the average (1.6 on a scale from 1 to 6 versus 2.3 for ''Brockhaus'', with 1 as the best and 6 as the worst). Wikipedia's coverage was also found to be more complete and up to date; however, ''Brockhaus'' was judged to be more clearly written, while several Wikipedia articles were criticized as being too complicated for non-experts, and many as too lengthy.

In its April 2008 issue British computing magazine ''PC Plus'' compared the English Wikipedia with the DVD editions of ''World Book Encyclopedia'' and ''Encyclopædia Britannica'', assessing for each the coverage of a series of random subjects. It concluded, "The quality of content is good in all three cases" and advised Wikipedia users "Be aware that erroneous edits do occur, and check anything that seems outlandish with a second source. But the vast majority of Wikipedia is filled with valuable and accurate information."

A 2008 paper in '' Reference Services Review'' compared nine Wikipedia entries on historical topics to their counterparts in ''Encyclopædia Britannica'', ''The Dictionary of American History'' and ''American National Biography Online''. The paper found that Wikipedia's entries had an overall accuracy rate of 80 percent, whereas the other encyclopedias had an accuracy rate of 95 to 96 percent.

A 2010 study assessed the extent to which Wikipedia pages about the history of countries conformed to the site's policy of verifiability. It found that, in contradiction of this policy, many claims in these articles were not supported by citations, and that many of those that were, sourced to popular media and government websites rather than to academic journal articles.

In April 2011, a study was published by Adam Brown of Brigham Young University in the journal '' PS Political Science & Politics'' which examined "thousands of Wikipedia articles about candidates, elections, and officeholders". The study found that while the information in these articles tended to be accurate, the articles examined contained many errors of omission.

A 2012 study co-authored by Shane Greenstein examined a decade of Wikipedia articles on United States politics and found that the more contributors there were to a given article, the more neutral it tended to be, in line with a narrow interpretation of Linus's law.

Reavley et al. (2012) compared the quality of articles on select mental health topics on Wikipedia with corresponding articles in ''Encyclopædia Britannica'' and a psychiatry textbook. They asked experts to rate article content with regard to accuracy, up-to-dateness, breadth of coverage, referencing and readability. Wikipedia scored highest on all criteria except readability, and the authors concluded that Wikipedia is as good as or better than ''Britannica'' and a standard textbook.

A 2014 perspective piece in the ''New England Journal of Medicine'' examined Wikipedia pages about 22 prescription drugs to determine if they had been updated to include the most recent FDA safety warnings. It found that 41% of these pages were updated within two weeks after the warning, 23% were updated more than two weeks later, and the remaining 36% had not been updated to include the warning as of more than 1 year later as of January 2014.

A 2014 study in the ''Journal of the American Pharmacists Association'' examined 19 Wikipedia articles about herbal supplements, and concluded that all of these articles contained information about their "therapeutic uses and adverse effects", but also concluded that "several lacked information on drug interactions, pregnancy, and contraindications". The study's authors therefore recommended that patients not rely solely on Wikipedia as a source for information about the herbal supplements in question.

Another study published in 2014 in '' PLOS ONE'' found that Wikipedia's information about pharmacology was 99.7% accurate when compared to a pharmacology textbook, and that the completeness of such information on Wikipedia was 83.8%. The study also determined that completeness of these Wikipedia articles was lowest (68%) in the category "pharmacokinetics" and highest (91.3%) in the category "indication". The authors concluded that "Wikipedia is an accurate and comprehensive source of drug-related information for undergraduate medical education".

Expert opinion

Librarians' views

In a 2004 interview with ''The Guardian'', self-described information specialist and Internet consultant Philip Bradley said that he would not use Wikipedia and was "not aware of a single librarian who would". He then explained that "the main problem is the lack of authority. With printed publications, the publishers have to ensure that their data are reliable, as their livelihood depends on it. But with something like this, all that goes out the window."

In 2005, the library at Trent University in Ontario stated Wikipedia had many articles that are "long and comprehensive", but that there is "a lot of room for misinformation and bias nda lot of variability in both the quality and depth of articles". It adds that Wikipedia has advantages and limitations, that it has "excellent coverage of technical topics" and articles are "often added quickly and, as a result, coverage of current events is quite good", comparing this to traditional sources which are unable to achieve this task. It concludes that, depending upon the need, one should think critically and assess the appropriateness of one's sources, "whether you are looking for fact or opinion, how in-depth you want to be as you explore a topic, the importance of reliability and accuracy, and the importance of timely or recent information", and adds that Wikipedia can be used in any event as a "starting point".

A 2006 review of Wikipedia by ''Library Journal'', using a panel of librarians, "the toughest critics of reference materials, whatever their format", asked "long standing reviewers" to evaluate three areas of Wikipedia (popular culture, current affairs, and science), and concluded: "While there are still reasons to proceed with caution when using a resource that takes pride in limited professional management, many encouraging signs suggest that (at least for now) Wikipedia may be granted the librarian's seal of approval". A reviewer who "decided to explore controversial historical and current events, hoping to find glaring abuses" said, "I was pleased by Wikipedia's objective presentation of controversial subjects" but that "as with much information floating around in cyberspace, a healthy degree of skepticism and skill at winnowing fact from opinion are required". Other reviewers noted that there is "much variation" but "good content abounds".

In 2007, Michael Gorman, former president of the American Library Association (ALA) stated in an ''Encyclopædia Britannica'' blog that "A professor who encourages the use of Wikipedia is the intellectual equivalent of a dietician who recommends a steady diet of Big Macs with everything".

''Information Today'' (March 2006) cites librarian Nancy O'Neill (principal librarian for Reference Services at the Santa Monica Public Library System) as saying that "there is a good deal of skepticism about Wikipedia in the library community" but that "she also admits cheerfully that Wikipedia makes a good starting place for a search. You get terminology, names, and a feel for the subject."

''PC Pro'' (August 2007) cites the head of the European and American Collection at the British Library, Stephen Bury, as stating "Wikipedia is potentially a good thing—it provides a speedier response to new events, and to new evidence on old items". The article concludes: "For ury the problem isn't so much the reliability of Wikipedia's content so much as the way in which it's used." "It's already become the first port of call for the researcher", Bury says, before noting that this is "not necessarily problematic except when they go no further". According to Bury, the trick to using Wikipedia is to understand that "just because it's in an encyclopedia (free, web or printed) doesn't mean it's true. Ask for evidence ... and contribute."

Articles on contentious issues

A 2006 article for the Canadian Library Association (CLA) discussed the Wikipedia approach, process and outcome in depth, commenting for example that in controversial topics, "what is most remarkable is that the two sides actually engaged each other and negotiated a version of the article that both can more or less live with". The author comments that:

Shi ''et al.'' extended this analysis in discussing "The wisdom of polarized crowds" in 2017 based on content analysis of all edits to English Wikipedia articles relating to politics, social issues and science from its start to December 1, 2016. This included almost 233,000 articles representing approximately 5 percent of the English Wikipedia. They wrote: "Political speech t least in the United Stateshas become markedly more polarized in recent years ... . spite early promise of the world-wide-web to democratize access to diverse information, increased media choice and social networking platforms ... reateecho chambers that ... degrade the quality of individual decisions, ... discount identity-incongruent opinions, stimulate and reinforce polarizing information ... foment conflict and even make communication counter-productive. Nevertheless, a large literature documents the largely positive effect that social differences can exert on the collaborative production of information, goods and services. Research demonstrates that individuals from socially distinct groups embody diverse cognitive resources and perspectives that, when cooperatively combined ... outperform those from homogeneous groups." They translated edit histories of millions of Wikipedia editors into a 7-point political identification scale and compared that with Wikipedia's six-level article quality score (stub, start, C, B, good, featured) assigned via a machine learning algorithm. They found that "articles attracting more attention tend to have more balanced engagement ... ndhigher polarization
is associated with higher quality."

Academia

Academics have also criticized Wikipedia for its perceived failure as a reliable source and because Wikipedia editors may have no expertise, competence, or credentials in the topics on which they contribute. Adrian Riskin, a mathematician in Whittier College commented that while highly technical articles may be written by mathematicians for mathematicians, the more general maths topics, such as the article on polynomials, are written in a very amateurish fashion with a number of obvious mistakes.

Because Wikipedia cannot be considered a reliable source, the use of Wikipedia is not accepted in many schools and universities in writing a formal paper, and some educational institutions have banned it as a primary source while others have limited its use to only a pointer to external sources. The criticism of not being a reliable source, however, may not only apply to Wikipedia but to encyclopedias in general—some university lecturers are not impressed when students cite print-based encyclopedias in assigned work. However, it seems that instructors have underestimated the use of Wikipedia in academia because of these concerns. Researchers and academics contend that while Wikipedia may not be used as a 100 percent accurate source for final papers, it is a valuable jumping off point for research that can lead to many possibilities if approached critically. What may be missing in academia is the emphasis on critical analysis in regards to the use of Wikipedia in secondary and higher education. We should not dismiss Wikipedia entirely (there are less inaccuracies than there are errors of omission) but rather begin to support it, and teach the use of Wikipedia as an education tool in tandem with critical thinking skills that will allow students to filter the information found on the online encyclopedia and help them critically analyze their findings.

An empirical study conducted in 2006 by a Business School lecturer in Information Systems at the University of Nottingham, the subject of a review on the technical website ''Ars Technica'', involving 55 academics asked to review specific Wikipedia articles that either were in their expert field (group 1) or chosen at random (group 2), concluded that: "The experts found Wikipedia's articles to be more credible than the non-experts. This suggests that the accuracy of Wikipedia is high. However, the results should not be seen as support for Wikipedia as a totally reliable resource as, according to the experts, 13 percent of the articles contain mistakes (10% of the experts reported factual errors of an unspecified degree, 3% of them reported spelling errors)."

The Gould Library at Carleton College in Minnesota has a web page describing the use of Wikipedia in academia. It asserts that "Wikipedia is without question a valuable and informative resource", but that "there is an inherent lack of reliability and stability" to its articles, again drawing attention to similar advantages and limitations as other sources. As with other reviews, it comments that one should assess one's sources and what is desired from them, and that "Wikipedia may be an appropriate resource for some assignments, but not for others." It cited Wikipedia co-founder Jimmy Wales' view that Wikipedia may not be ideal as a source for all academic uses, and (as with other sources) suggests that at the least, one strength of Wikipedia is that it provides a good starting point for current information on a very wide range of topics.

In 2007, the ''Chronicle of Higher Education'' published an article written by Cathy Davidson, Professor of Interdisciplinary Studies and English at Duke University, in which she asserts that Wikipedia should be used to teach students about the concepts of reliability and credibility.

In 2008, Hamlet Isakhanli, founder and president of Khazar University, compared the ''Encyclopædia Britannica'' and English Wikipedia articles on Azerbaijan and related subjects. His study found that Wikipedia covered the subject much more widely, more accurately and in more detail, though with some lack of balance, and that Wikipedia was the best source for the first approximation.

In 2011, Karl Kehm, associate professor of physics at Washington College, said: "I do encourage y studentsto use ikipediaas one of many launch points for pursuing original source material. The best Wikipedia entries are well researched with extensive citations".

Some academic journals do refer to Wikipedia articles, but are not elevating it to the same level as traditional references. For instance, Wikipedia articles have been referenced in "enhanced perspectives" provided on-line in the journal ''Science''. The first of these perspectives to provide a hyperlink to Wikipedia was "A White Collar Protein Senses Blue Light", and dozens of enhanced perspectives have provided such links since then. The publisher of ''Science'' states that these enhanced perspectives "include hypernotes—which link directly to websites of other relevant information available online—beyond the standard bibliographic references".

Journalism and use of Wikipedia in the newsroom

In his 2014 book ''Virtual Unreality'', Charles Seife, a professor of journalism at New York University, noted Wikipedia's susceptibility to hoaxes and misinformation, including manipulation by commercial and political organizations "masquerading as common people" making edits to Wikipedia. In conclusion, Seife presented the following advice:

Seife observed that when false information from Wikipedia spreads to other publications, it sometimes alters truth itself. On June 28, 2012, for example, an anonymous Wikipedia contributor added the invented nickname "Millville Meteor" to the Wikipedia biography of baseball player Mike Trout. A couple of weeks later, a ''Newsday'' sports writer reproduced the nickname in an article, and "with that act, the fake nickname became real". Seife pointed out that while Wikipedia, by some standards, could be described as "roughly as accurate" as traditional publications, and is more up to date, "there's a difference between the kind of error one would find in Wikipedia and what one would in ''Britannica'' or ''Collier's'' or even in the now-defunct Microsoft Encarta encyclopedia ... the majority of hoaxes on Wikipedia could never have appeared in the old-fashioned encyclopedias." Dwight Garner, reviewing Seife's book in ''The New York Times'', said that he himself had "been burned enough times by bad online information", including "Wikipedia howlers", to have adopted a very sceptical mindset.

In November 2012, Brian Leveson was accused of having forgotten "one of the elementary rules of journalism" when he named a "Brett Straub" as one of the founders of ''The Independent'' newspaper in his report on the culture, practices and ethics of the British press. The name had been added to the Wikipedia article on ''The Independent'' over a year prior, and turned out to be that of a 25-year-old Californian, whose friend had added his name to a string of Wikipedia pages as a prank. Straub was tracked down by ''The Telegraph'' and commented, "The fact someone, especially a judge, has believed something on Wikipedia is kind of shocking. My friend went on and edited a bunch of Wikipedia pages and put my name there. ..I knew my friend had done it but I didn't know how to change them back and I thought someone would. At one point I was the creator of Coca-Cola or something. You know how easy it is to change Wikipedia. Every time he came across a red linked name he put my name in its place."

A 2016 BBC
...