 | This is anessay on theVerifiability policy and theCiting Sources guideline. It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one ofWikipedia's policies or guidelines, as it has not beenthoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints. |
 | This page in a nutshell: When citing material in an article, it is better to cite a couple of great sources than a stack of decent or sub-par ones. |
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Wikipedia policy requires all content within articles to beverifiable. While addinginline citations is helpful, adding too many can causecitation clutter, making articles look untidy in read mode and difficult to navigate in markup edit mode. If a page features citations that are mirror pages of others, or which simply parrot the other sources, they contribute nothing to the article's reliability and are detrimental to its readability.
One cause of "citation overkill" isedit warring, which can lead to examples like "Graphism is the study[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] of ...". Extreme cases have seen fifteen or more footnotes after a single word, as an editor tries to strengthen their point or the overall notability of the subject with extra citations, in the hope that others will accept that reliable sources support it. Similar circumstances can also lead to overkill with legitimate sources, when existing sources have been repeatedly removed or disputed on spurious grounds or against consensus.
Another common cause of citation overkill is simply that people want the source they've seen to be included in the article too, so they just tack it onto the end of existing content without making an effort to actually add anynew content.
The purpose of any article is first and foremost to beread – unreadable articles do not give our readers any material worth verifying. It is also important for an article to be verifiable. Without citations, we cannot know that the material isn't just made up, unless it is a case ofcommon sense (seeWP:BLUE). A good rule of thumb is to cite at least one inline citation for each section of text that may bechallenged or is likely to be challenged, or for direct quotations. Two or three may be preferred for more controversial material or as a way of preventinglinkrot for online sources, but more than three should generally be avoided; if four or more are needed, considerbundling (merging) the citations.
Not only does citation overkill impact the readability of an article, it cancall the notability of the subject into question by editors. A well-meaning editor may attempt to make a subject which does not meet Wikipedia'snotability guidelinesappear to be notable through sheer quantity of sources, without actually paying any attention to thequality of the sources. Ironically, this serves as a red flag to experienced editors that the article needs scrutiny and that each citation needs to be verified carefully to ensure that it was really used to contribute to the article.
It is possible that an editor who is trying to promote an article toGA-class (good article status) might add citations to basic facts such as "...the sky is blue..."[6]. While this might be a good thing in their eyes, the fact that thesky is blue does notusually require a citation. In all cases, editors should usecommon sense. In particular, remember thatWikipedia is not a dictionary and we do not need citations for the meanings of everyday words and phrases.
A common form of citation overkill is adding sources to an article without regard as to whether they support substantive or noteworthy content about the topic. This may boost the number of footnotes and create a superficial appearance of notability, which can obscure a lack of substantive, reliable, and relevant information. This phenomenon is especially common in articles about people and organizations.
Examples of this type of citation overkill include:
Some people might try to rest notability on a handful of sources that do not contribute, while other people might try to build the pile of sources up into the dozens or even hundreds instead – so this type of citation overkill may require special attention. Either way, the principle is the same: Sources support notability based on what they say about the topic, not just the number of footnotes present. An article with just four or five really good sources is considered better referenced than an article that cites 500 bad ones.
Overloading an article with bad citations can backfire if the article is nominated for deletion. Participators may not want to look at all one hundred citations, and they may instead choose to look at just a smaller sample. If they find only unreliable sources or sources that do not discuss the subject in depth, they could recommend deletion. The good sources could be missed.
Draft articles with excessive citations are likely to be ignored by volunteer reviewers in thearticles for creation (AfC) process, contributing to the backlog and resulting in a delay of several months before the draft is reviewed, usually only to be declined.
Material that is repeated multiple times in an article does not require an inline citation for every mention. If you say an elephant is a mammal more than once, provide one only at the first instance.
Avoid cluttering text with redundant citations like this:
In addition, as perWP:PAIC, citations should be placed at the end of the passage that they support. If one source alone supports consecutive sentences in the same paragraph, one citation of it at the end of the final sentence is sufficient. It is not necessary to include a citation for each individual consecutive sentence, as this is overkill. This does not apply to lists or tables, nor does it apply whenmultiple sources support different parts of a paragraph or passage.
This is correct:
This is also correct, but is an example of overkill:
If consecutive sentences are supported by the same reference, and that reference's inline citation is placed at the end of the paragraph as described atWP:CITETYPE, an editor may want to consider using Wikipedia'shidden text syntax<!-- --> to place hiddenref name tags at the end of each sentence. Doing so may benefit others adding material to that paragraph in the future. If that happens, they can uncomment the hidden citations and switch to citing references after every sentence. Having hidden citations could cause confusion, especially among inexperienced editors, so the approach is strictly optional and should be used cautiously.
Another common form of citation overkill is to cite multiple reprintings of the same content in different publications – such as several different newspapers reprinting the samewire service article, or a newspaper or magazine article getting picked up by anews aggregator – as if they constituted distinct citations. Such duplicated citations may be piled up as multiple references for the same fact or they may be split up as distinct footnotes for different pieces of content, so watching out for this type of overkill may sometimes require special attention.
This type of overkill should be resolved by merging all of the citations into a single one and stripping unhelpful repetitions – when possible, the retained citation should be the originator of the content rather than a reprinter or aggregator, but if this is not possible (e.g. some wire service articles) then retain themost reliable and widely distributed available reprinter (for example, if the same article has been linked to bothThe New York Times andThe Palookaville Herald, thenThe New York Times should be retained as the citation link.)
A similar case is redundant citation of an article that got its information from an article we have already cited. An exception, to many scientific and technical editors, is when we cite a peer-reviewedliterature review and also cite some of the original research papers the review covers. This is often felt to provide better utility for academic and university-student users of Wikipedia, and improvedverifiability of details, especiallyin medical topics. Similar concerns about thebiographies of living people may sometimes result in "back-up" citations to original reportage of statements or allegations that are later repeated by secondary sources that provide an overview.
In controversial topics, sometimes editors will stack citations that do not add additional facts or really improve article reliability, in an attempt to "outweigh" an opposing view when the article covers multiple sides of an issue or there are competing claims. This is something like aPoV fork andedit war at once, happening inside the article's very content itself, and is an example of the fallacy ofproof by assertion: "According to scholars in My School of Thought,Claim 1.[1][2][3][4][5] However, experts at The Other Camp suggest thatClaim 2.[6][7][8][9][10]"
If this is primarily an inter-editor dispute over acore content policy matter (point of view,source interpretation, orverifiability of a claim), talk page discussion needs to proceed toward resolving the matter and balancing the article. If the dispute seems intractable among the regular editors of the article, try therequests for comments process; the applicable NPOV, NOR or RSnoticeboard; orformal dispute resolution.
If the matter is the subject of real-world dispute in reliable sources, our readers actually need to know the conflict exists and what its parameters are (unless one of the conflicting views is afringe viewpoint). Competing assertions with no context are not encyclopedic. Instead, the material should be rewritten to outline the nature of the controversy, ideally beginning withsecondary sources that independently describe the conflicting viewpoints or data, with additional, less independent sources cited only where pertinent, for verification of more nuanced claims made about the views or facts as represented by the conflicting sources. Sources that are opinional in nature – op-eds, advocacy materials, and otherprimary sources – can usually simply be dropped unless necessary to verifyquotations that are necessary for reader understanding of the controversy.
Contrary views (and approaches to addressing their concerns) include:
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Try to construct passages so that an entire sentence or more can be cited to a particular source, instead of having sentences that each require multiple sources.
Sometimes it may be possible to salvage sources from a citekill pileup by simply moving them to other places in the article. Sometimes, a source which has been stacked on top of another source may also support other content in the article that is presently unreferenced, or may support additional content that isn't in the article at all yet, and can thus be saved by simply moving it to the other fact or adding new content to the article.
If there are six citations on a point of information, and the first three are highly reputable sources (e.g., books published by university presses), and the last three citations are less reputable or less widely circulated (e.g., local newsletters), then trim out those less reputable sources.
If all of the citations are to highly reputable sources, another way to trim their number is to make sure that there is a good mix oftypes of sources. For example, if the six citations include two books, two journal articles, and two encyclopedia articles, the citations could be trimmed down to one citation from each type of source. Comprehensive works on a topic often include many of the same points. Not all such works on a topic need be cited – choose the one or ones that seem to be the best combination of eminent, balanced, and current.
In some cases, such as articles related to technology or computing or other fields that are changing very rapidly, it may be desirable to have the sources be as up-to-date as possible. In these cases, a few of the older citations could be removed.
For many subjects, some sources are official or otherwise authoritative, while others are only interpretive, summarizing, or opinionated. If the authoritative sources are not controversial, they should generally be preferred. For example, a company's own website is probably authoritative for an uncontroversial fact like where its headquarters is located, so newspaper articles need not be cited on that point. TheWorld Wide Web Consortium's specifications are, by definition, more authoritative about HTML and CSS standards than third-party Web development tutorials.
If there is a good reason to keep multiple citations, for example, to avoid perennial edit warring or because the sources offer a range of beneficial information, clutter may be avoided by merging the citations into a single footnote. This can be done by putting, inside the reference, bullet points before each source, as inthis example, which producesall of the sources under a single footnote number. Within a simple text citation, semicolons can be used to separate multiple sources.
Each of these articles has been corrected. Links here are to previous versions where a citation problem existed.