Wikipedia:Reliable sources/rewrite

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Some sources are more reliable than others. Sources that are more reliable are preferred over those that are less reliable. However, reliability is not a binary condition; rather, there are degrees of reliability.

Why use reliable sources?

Sources are used for one of three purposes within Wikipedia.

To support an assertion made in an article. Sources used in this manner should be directly referenced for the point that is being supported.
To provide amplifying material around an assertion to provide context or illustration to the reader. Sources used in this manner can be directly referenced or provided under the References heading.
Author credit, see Wikipedia:Copyrights for further discussion.

For these three purposes, the level of reliability around those sources assures the reader that what is being presented meets the Wikipedia standards for verifiability, originality, and neutrality. Accurate citation allows the reader to go to those sources and gives appropriate credit to the author of the work.

Assessing the reliability of the sources used in an article allows the editor to caveat the statements made, identifying where weaknesses are present and where there may be alternative positions on a statement, with a qualitative opinion presented on the relative arguments based on the quality of sources.

If all sources for a given statement or topic are of low reliability this should indicate to the reader that the content should be treated with a degree of scepticism or that the topic is not suitable for inclusion.

Aspects of reliability

In assessing the suitability of a source for the purposes of research a number of aspects should be considered:

Attributability—The more we know about the originator, either organisation or individual, of source material, the better. This helps us measure of the authority of the content:

Expertise of the originator with respect to the subject—An academic expert in one subject is more reliable when writing about that subject than when writing about another. For example, a biologist is more reliable when writing about biology than when writing about nuclear physics.

Bias of the originator with respect to the subject—If an author has some reason to be biased, or admits to being biased, this should be taken into account when reporting his or her opinion. This is not to say that the material is not worthy of inclusion, but please take a look at our policy on Neutral point of view.

Editorial oversight—A publication with a declared editorial policy will have greater reliability than one without, since the content is subject to verification. Self published sources such as personal web pages, personally published print runs and blogs have not been subject to any form of independent fact-checking and so have lower levels of reliability than published news media (The Economist) and other sources with editorial oversight, which is less reliable itself than professional or peer reviewed journal (Nature).

Replicability—Can the conclusions of the source be reached using the information available or is there any indication of gaps in the thinking or process of derivation. Essentially are there any leaps of faith in the source:

Declaration of sources—A source which is explicit about the data from which it derives its conclusions is more reliable than one which does not, ideally a source should describe the collection process and analysis method.

Confidentiality—Sources which are considered confidential by the originating publisher may hold uncertain authority. Given that the original cannot be used to validate the reference then these should be treated with caution.

Corroboration—Do the conclusions match with other sources in the field which have been derived independently. If two or more independent originators agree, in a reliable manner, then the conclusions become more reliable. Care must be taken to establish that corroboration is indeed independent, to avoid an invalid conclusion based on uncredited origination.

Recognition by other reliable sources — A source may be considered more reliable if another source which is generally considered reliable cites or recommends it.

Age of the source and rate of change of the subject—Where a subject has evolved or changed over time a long standing source may not be accurate with respect to the current situation. To interpret utility one must appreciate how the subject has changed and has that change impacted on any of the salient points of the source information. Historical or out of date sources may be used to demonstrate evolution of the subject but should be treated with caution where used to illustrate the subject. Should now newer sources be available it is reasonable to caveat use of sources with an indication of the age and the resulting reduction in reliability.

Persistence—Should a reader go to the cited source to validate a statement, or to gain further understanding of the topic, then the form cited should remain stable, continuing to contain the information used by the editor to support the words. In this sense a book or journal citation is superior to an online source where the link may become broken. Some web resources have editorial policies which lead to a lack of persistence therefore web citations should be treated with caution.

These issues are particularly pertinent to Wikipedia where various editors involved in an article may have their own expertise or position with respect to the topic. Not all sources are comparable in their reliability with respect to a topic, and some sources will have differing degrees of reliability with respect to the subject in different contexts.

In general, a topic should use the most reliable sources that are available to its editors. Common sense is required to determine what sources to use; this guideline cannot be applied robotically. If you have questions about a source's reliability, discuss with other editors on the article's talk page, or if the source is already used in the article, you can draw attention to it with the {{unreliable}} template.

Types of source material

Three classes of course exist, each of which can be used within Wikipedia:

Primary—The provision of direct evidence about the subject. Primary sources would be produced by a participant or direct observer. Official reports, letters and eyewitness accounts. Primary material may require interpretation, interpolation, extrapolation or corroboration each of which would constitute original research. Wikipedia articles may use primary sources only if they meet the preceding principles and then only to make purely descriptive claims about the topic.

Secondary—The informed and expert interpretation, interpolation, extrapolation or corroboration of primary sources to synthesise a conclusion. In general, Wikipedia articles should rely on reliable secondary sources.

Tertiary—Summarised material drawn from secondary sources. These sources may lack adequate coverage of the topic to be considered comprehensive where arguments are subtle and nuanced. Tertiary sources can be used to support the declaration of simple data such as dates and dimensions however should be avoided if secondary sources provide coverage.

Ideally a topic should contain reference to a number of independent sources to demonstrate a rigorous approach to the development of the article.

Convenience links

Also see Wikipedia:Convenience links

The term "convenience link" is typically used to indicate a link to a copy of a resource somewhere on the internet, offered in addition to a formal citation to the same resource in its original format. For example, an editor providing a citation to Adam Smith's famous work The Wealth of Nations might choose to include both a citation to a published copy of the work and a link to the work on the internet, as follows:

Smith, Adam (1904) [1776]. Edwin Cannan (ed.). The Wealth of Nations (Fifth ed.). London: Methuen and Co., available at Wikisource

Such links are unique in how reliablility is applied. It is important to ensure that the copy being linked is a true copy of the original, without any comments, amendations, edits or changes. When the "convinience link" is hosted by a site that is considered reliable on its own, this is relatively easy to assume. However, when such a link is hosted on a less reliable site, the linked version should be checked for accuracy against the original.

Examples

See Wikipedia:Reliable sources/examples for examples of sources and to what degree editors consider them to be reliable or not.

References

External links

How to Read a Primary Source, Reading, Writing, and Researching for History: A Guide for College Students, Patrick Rael, 2004.
How to Read a Secondary Source, Reading, Writing, and Researching for History: A Guide for College Students, Patrick Rael, 2004.