Wikipedia:Verifiability
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This page documents an official English Wikipedia policy, a widely accepted standard that should normally be followed by all editors. Any edit to this page should reflect consensus. If in doubt, consider discussing changes on the talk page. |
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This page in a nutshell: Material challenged or likely to be challenged, and all quotations, must be attributed to a reliable, published source. |
| Wikipedia policy |
|---|
| Global principles |
| What Wikipedia is not Ignore all rules |
| Content standards |
| Neutral point of view Verifiability No original research Biographies of living persons |
| Working with others |
| Civility No personal attacks Harassment No legal threats Consensus Dispute resolution |
| More |
| Full list of policies List of guidelines |
The threshold for inclusion in Wikipedia is verifiability, not truth—that is, whether readers are able to check that material added to Wikipedia has already been published by a reliable source, not whether we think it is true. Editors should provide a reliable source for quotations and for any material that is challenged or likely to be challenged, or the material may be removed.
Wikipedia:Verifiability is one of Wikipedia's core content policies. The others are Wikipedia:No original research and Wikipedia:Neutral point of view. Jointly, these policies determine the type and quality of material that is acceptable in Wikipedia articles. They should not be interpreted in isolation from one another, and editors should familiarize themselves with all three. To discuss the reliability of particular sources, see the reliable sources noticeboard.
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[edit] Burden of evidence
- For how to write citations, see Wikipedia:Citing sources
The burden of evidence lies with the editor who adds or restores material. All quotations and any material challenged or likely to be challenged must be attributed to a reliable, published source using an inline citation.[1] The source cited must clearly support the information as it is presented in the article.[2] The source should be cited clearly and precisely to enable readers to find the text that supports the article content in question. Editors should cite sources fully, providing as much publication information as possible, including page numbers when citing books.
If no reliable, third-party sources can be found for an article topic, Wikipedia should not have an article on it.
Any material lacking a reliable source may be removed, but editors might object if you remove material without giving them sufficient time to provide references, and it has always been good practice, and expected behavior of Wikipedia editors (in line with our editing policy), to make reasonable efforts to find sources oneself that support such material, and cite them.
If you want to request a source for an unsourced statement, consider tagging a sentence by adding the {{fact}} template, a section with {{unreferencedsection}}, or the article with {{refimprove}} or {{unreferenced}}. Alternatively, you may leave a note on the talk page requesting a source, or you may move the material to the talk page.
Do not leave unsourced or poorly sourced information that may damage the reputation of living persons or organizations in articles and do not move it to the talk page (See Wikipedia:Biographies of living persons for details of this policy). As Wikipedia founder Jimmy Wales has put it:
I can NOT emphasize this enough. There seems to be a terrible bias among some editors that some sort of random speculative 'I heard it somewhere' pseudo information is to be tagged with a 'needs a cite' tag. Wrong. It should be removed, aggressively, unless it can be sourced. This is true of all information, but it is particularly true of negative information about living persons.
–Jimmy Wales [3]
[edit] Sources
- See also: Wikipedia:Neutral point of view, Wikipedia:Biographies of living persons, and Wikipedia:No original research#Primary, secondary and tertiary sources
[edit] Reliable sources
Articles should rely on reliable, third-party published sources with a reputation for fact-checking and accuracy.[4] Reliable sources are necessary both to substantiate material within articles and to give credit to authors and publishers in order to avoid plagiarism and copyright violations. Sources should directly support the information as it is presented in an article and should be appropriate to the claims made: exceptional claims require high-quality sources.
In general, the most reliable sources are peer-reviewed journals and books published in university presses; university-level textbooks; magazines, journals, and books published by respected publishing houses; and mainstream newspapers. As a rule of thumb, the greater the degree of scrutiny involved in checking facts, analyzing legal issues, and scrutinizing the evidence and arguments of a particular work, the more reliable it is.
Academic and peer-reviewed publications are highly valued and usually the most reliable sources in areas where they are available, such as history, medicine and science. Material from reliable non-academic sources may also be used in these areas, particularly if they are respected mainstream publications. The appropriateness of any source always depends on the context. Where there is disagreement between sources, their views should be clearly attributed in the text.
For a guideline discussing the reliability of particular types of sources, see Wikipedia:Reliable sources (WP:RS). Because policies take precedence over guidelines, in the case of an inconsistency between this page and that one, this page has priority, and WP:RS should be updated accordingly. To discuss the reliability of specific sources, consult the Wikipedia:Reliable sources/Noticeboard.
All articles must adhere to Wikipedia's neutrality policy, fairly representing all majority and significant-minority viewpoints that have been published by reliable sources, in rough proportion to the prominence of each view. Tiny-minority views and fringe theories need not be included, except in articles devoted to them.
Reliable sources may be print-only, electronic-only or be available in both print and electronic formats.
[edit] Self-published and other questionable sources
[edit] Self-published sources
Anyone can create a website or pay to have a book published. For this reason, it is usually not acceptable in Wikipedia to cite self-published books, newsletters, personal websites, open wikis, blogs, knols, podcasts, vcasts, patents, patent applications, forum postings, and similar sources.[5]
Self-published work is acceptable to use in some circumstances, with limitations. For example, material may sometimes be cited which is self-published by an established expert on the topic of the article, whose work in the relevant field has previously been published by reliable third-party publications. However, caution should be exercised when using such sources: if the information in question is really worth reporting, someone else is likely to have done so. For example, a reliable self-published source on a given subject is likely to have been cited on that subject as authoritative by a reliable source.
Self-published sources should never be used as third-party sources about living persons, even if the author is a well-known professional researcher or writer; see WP:BLP#Reliable sources.
Self-published work by non-experts may also be used in limited circumstances, as described below.
Articles and posts on Wikipedia, or other websites that mirror Wikipedia content, may not be used as sources.
[edit] Questionable sources
Just because a source is not self-published does not automatically make it reliable. Questionable sources are those with a poor reputation for fact-checking. Such sources include websites and publications that rely heavily on rumors and personal opinions, are promotional in nature, or express views that are widely acknowledged as extremist or pseudoscience. Because of this, they can be treated similarly to the way self-published sources are treated. Questionable sources should only be used as sources of information about themselves as described below. Any contentious claims the source has made about third parties should not be repeated in Wikipedia, unless those claims have also been discussed by a reliable source.
[edit] Using self-published and questionable sources as sources on themselves
Self-published or questionable sources may be used as sources of information about themselves, especially in articles about themselves, without the requirement that they be published experts in the field, so long as:
- the material used is relevant to the notability of the subject of the article;
- it is not unduly self-serving;
- it does not involve claims about third parties;
- it does not involve claims about events not directly related to the subject;
- there is no reason to doubt its authenticity;
- the article is not based primarily on such sources;
[edit] Non-English sources
Because this is the English Wikipedia, for the convenience of our readers, editors should use English-language sources in preference to sources in other languages, assuming the availability of an English-language source of equal quality, so that readers can easily verify that the source material has been used correctly. Where editors translate any direct quote, they should quote the relevant portion of the original, non-English text in a footnote or in the article. Translations published by reliable sources are preferred over translations made by Wikipedia editors.
[edit] Exceptional claims require exceptional sources
- See also: Wikipedia:Fringe theories
Certain red flags should prompt editors to examine the sources for a given claim:
- surprising or apparently important claims not covered by mainstream sources;
- reports of a statement by someone that seems out of character, embarrassing, controversial, or against an interest they had previously defended;
- claims that are contradicted by the prevailing view within the relevant community, or which would significantly alter mainstream assumptions, especially in science, medicine, history, politics, and biographies of living persons. This is especially true when proponents consider that there is a conspiracy to silence them.
Exceptional claims in Wikipedia require high-quality sources; if such sources are not available, the material should not be included. Also be sure to adhere to other policies, such as the policy for biographies of living persons and the undue weight provision of Wikipedia:Neutral point of view.
[edit] See also
- Wikipedia:Core content policies
- Wikipedia:Free online resources
- Wikipedia:Fringe theories
- Wikipedia:Template messages/Sources of articles
- WikiProject Fact and Reference Check
- WikiProject Resource Exchange
[edit] Notes
- ^ When content in Wikipedia requires direct substantiation, the established convention is to provide an inline citation to the supporting references. The rationale is that this provides the most direct means to verify whether the content is consistent with the references. Alternative conventions exist, and are acceptable if they provide clear and precise attribution for the article's assertions, but inline citations are considered 'best practice' under this rationale. For more details, please consult Wikipedia:Citing sources#How to cite sources.
- ^ When there is dispute about whether the article text is fully supported by the given source, direct quotes from the source and any other details requested should be provided as a courtesy to substantiate the reference.
- ^ Jimmy Wales (2006-05-16). ""Zero information is preferred to misleading or false information"". WikiEN-l electronic mailing list archive. Retrieved on 2006-06-11.
- ^ The word "source", as used in Wikipedia, has three related meanings: the piece of work itself, the creator of the work, and the publisher of the work. All three affect reliability.
- ^ "Blogs" in this context refers to personal and group blogs. Some newspapers and other periodicals host interactive columns that they call blogs, and these may be acceptable as sources so long as the writers are professionals and the blog is subject to the organization's full editorial control. Where a news organization publishes the opinions of a professional but claims no responsibility for the opinions, the writer of the cited piece should be attributed (e.g., "Jane Smith has suggested..."). Posts left by readers may never be used as sources.
[edit] Further reading
- Jimmy Wales. "WikiEN-l insist on sources", WikiEN-l mailing list, July 19, 2006.
- False Authority On the importance of looking for many sources.
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