Verifiability means that readers should be able to verify that claims in Wikipedia are supported by reliable sources. Editors should provide a reliable source for quotations and for any material that is challenged or is likely to be challenged.
Wikipedia:Verifiability is one of Wikipedia's core content policies. The others are Wikipedia:No original research and Wikipedia:Neutral point of view. They should be interpreted in context with one another.
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 should be attributed to a reliable published source, preferably using an inline citation. [1] The source should be cited clearly and precisely to enable readers to find the text that supports the article content in question.
Any material lacking a reliable source may be removed, but editors may object if you remove material without giving them a chance to provide references. If you want to request a source for an unsourced statement, editors may tag a sentence by adding the {{ fact}} template, a section with {{ unreferencedsection}}, or the article with {{ refimprove}} or {{ unreferenced}}. Editors may also consider moving it to the talk page and requesting sources. The exception to this is that any unsourced material may be removed from biographical material about living persons at any time, and should be removed immediately if it is likely to be contentious.
Sources
Reliable sources
Articles should usually cite reliable independent sources with a reputation for fact-checking and accuracy. [2] Reliable sources are needed for good citations and avoiding plagiarism. Sources should be relevant to the topic and directly support the information presented in the article.
In general, the most reliable sources are peer-reviewed journals; books published in university presses; university-level textbooks; material published by respected publishing houses; writing and speeches of established experts. As a rule of thumb, more stringent fact-checking and greater professional reputation indicate higher reliability. 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.
Questionable sources
Questionable sources are those with a poor reputation for fact-checking. Such sources include websites and publications that express views that are widely acknowledged as extremist, are promotional in nature, or rely heavily on rumors and personal opinions. Questionable sources should only be used in articles about themselves. (See below.)
Self-published sources (online and paper)
Anyone can create a website or pay to have a book published, then claim to be an expert in a certain field. For that reason, self-published books, newsletters, personal websites, open wikis, blogs, forum postings, and similar sources are largely not acceptable.
Self-published material may be acceptable when produced by an established expert whose work in the relevant field has been released by a reliable publisher, or has been noted for expertise by reliable sources or otherwise possesses a professional reputation. Caution should be exercised: If the information is important, it likely someone else has published material about it.
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.
Articles and posts on Wikipedia may not be used as sources.
Self-published and questionable sources in articles about themselves
Self-published and questionable sources may be used as sources in articles about themselves, so long as:
- it is not contentious;
- it is not unduly self-serving;
- there is no reasonable doubt as to who authored it;
- the article is not based primarily on such sources.
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, so that readers can easily verify that the source material has been used correctly.
Where editors use a non-English source to support material that others might challenge, or translate any direct quote, they need to quote the relevant portion of the original text in a footnote or in the article, so readers can check that it agrees with the article content. Translations published by reliable sources are preferred over translations made by Wikipedia editors.
Exceptional claims require exceptional sources
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 BLPs.
Exceptional claims in Wikipedia require reliable sources; if such sources are not available, the material should not be included.
See also
- Wikipedia:Template messages/Sources of articles
- WikiProject Fact and Reference Check
- Forum for Encyclopedic Standards
- WikiProject Resource Exchange
- Wikipedia:Free online resources
- Wikipedia:NPOV, V and OR
Notes and references
- ^ For more details, please consult Wikipedia:Citing_sources#How_to_cite_sources.
- ^ 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.
Further reading
- Jimmy Wales. "WikiEN-l insist on sources", WikiEN-l mailing list, July 19, 2006.
Verifiability means that readers should be able to verify that claims in Wikipedia are supported by reliable sources. Editors should provide a reliable source for quotations and for any material that is challenged or is likely to be challenged.
Wikipedia:Verifiability is one of Wikipedia's core content policies. The others are Wikipedia:No original research and Wikipedia:Neutral point of view. They should be interpreted in context with one another.
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 should be attributed to a reliable published source, preferably using an inline citation. [1] The source should be cited clearly and precisely to enable readers to find the text that supports the article content in question.
Any material lacking a reliable source may be removed, but editors may object if you remove material without giving them a chance to provide references. If you want to request a source for an unsourced statement, editors may tag a sentence by adding the {{ fact}} template, a section with {{ unreferencedsection}}, or the article with {{ refimprove}} or {{ unreferenced}}. Editors may also consider moving it to the talk page and requesting sources. The exception to this is that any unsourced material may be removed from biographical material about living persons at any time, and should be removed immediately if it is likely to be contentious.
Sources
Reliable sources
Articles should usually cite reliable independent sources with a reputation for fact-checking and accuracy. [2] Reliable sources are needed for good citations and avoiding plagiarism. Sources should be relevant to the topic and directly support the information presented in the article.
In general, the most reliable sources are peer-reviewed journals; books published in university presses; university-level textbooks; material published by respected publishing houses; writing and speeches of established experts. As a rule of thumb, more stringent fact-checking and greater professional reputation indicate higher reliability. 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.
Questionable sources
Questionable sources are those with a poor reputation for fact-checking. Such sources include websites and publications that express views that are widely acknowledged as extremist, are promotional in nature, or rely heavily on rumors and personal opinions. Questionable sources should only be used in articles about themselves. (See below.)
Self-published sources (online and paper)
Anyone can create a website or pay to have a book published, then claim to be an expert in a certain field. For that reason, self-published books, newsletters, personal websites, open wikis, blogs, forum postings, and similar sources are largely not acceptable.
Self-published material may be acceptable when produced by an established expert whose work in the relevant field has been released by a reliable publisher, or has been noted for expertise by reliable sources or otherwise possesses a professional reputation. Caution should be exercised: If the information is important, it likely someone else has published material about it.
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.
Articles and posts on Wikipedia may not be used as sources.
Self-published and questionable sources in articles about themselves
Self-published and questionable sources may be used as sources in articles about themselves, so long as:
- it is not contentious;
- it is not unduly self-serving;
- there is no reasonable doubt as to who authored it;
- the article is not based primarily on such sources.
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, so that readers can easily verify that the source material has been used correctly.
Where editors use a non-English source to support material that others might challenge, or translate any direct quote, they need to quote the relevant portion of the original text in a footnote or in the article, so readers can check that it agrees with the article content. Translations published by reliable sources are preferred over translations made by Wikipedia editors.
Exceptional claims require exceptional sources
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 BLPs.
Exceptional claims in Wikipedia require reliable sources; if such sources are not available, the material should not be included.
See also
- Wikipedia:Template messages/Sources of articles
- WikiProject Fact and Reference Check
- Forum for Encyclopedic Standards
- WikiProject Resource Exchange
- Wikipedia:Free online resources
- Wikipedia:NPOV, V and OR
Notes and references
- ^ For more details, please consult Wikipedia:Citing_sources#How_to_cite_sources.
- ^ 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.
Further reading
- Jimmy Wales. "WikiEN-l insist on sources", WikiEN-l mailing list, July 19, 2006.