The medical sciences are evidence-based, and because it is a field in which wrong information can be harmful, it is important that questions and answers also be evidence-based. The quality of references matters, as validity varies widely - from internationally validated clinical guidelines to an individual's opinion blog.

This is a discussion of the strength of evidence that is accepted here. Please edit the answers, and add comments at the bottom if you want.

Here is a previous discussion that can be brought into this discussion: Permissibility of non-medical sources


2 Answers 2


Excellent Sources

Sources that provide information based on validated clinical decision rules, meta-analysis of high-quality studies, etc.

More examples can be found in the reliable sources list

Appropriate Sources for Common Knowledge

Sources that are trustworthy enough to use them as references for common knowledge:

  • WebMD, Medscape, Mayo Clinic
  • Wikipedia.org (if it is directly pertinent and you've looked at the reference supporting the specific information as sometimes it is wrong; prefer to use the references cited in Wikipedia directly)

Good Sources but not easily accessible, so use alternatives when possible:

  • UpToDate: (a clinical resource commonly used, peer reviewed and evidence-based with extensive high quality resources; however, much of its content requires a rather pricey subscription. If possible, link to the references they use.)
  • Primary literature articles behind pay walls

Poor Sources

Sources that are not verifiable by other users:

  • Individuals' blogs (Note: if the site links to high quality resources, use those resources as your links instead of the blog)
  • Family members
  • "I know a doctor who..."
  • "I am a doctor who..."
  • "When this happened to me, I..."


  • Clinical/professional education and experience does offer insight; however, but no one here can be validated as a professional. Therefore other evidence is always preferred. However, under some circumstances a professional can refer to experience if (1) it's not the primary source of evidence and (2) if prefaced appropriately "In my clinical experience, I have never seen this manifested..."

  • Concerning junk science; although it should be more common on the bottom of our list of quality sources than near the top, no journal or book or study represents the ultimate truth. Check the questions and aims, the methodology, the statistics, results and conclusions of your sources. Do not trust blindly everything that turns up on PubMed. Quality comes even there in a range of colours.

  • Science is no belief system but a process. A single study is good but usually not enough to reach conclusive evidence. Check the age of these publications, look for contradictions, retractions or refutations, conflicting information or conflicts of interests. Use more than one source if possible and weigh the facts available to you. Do likewise with the answers you read here. Check the reasoning, the sources and the conclusions for their soundness. Then comment and vote.

Some help for reading, understanding and interpreting scientific and medical papers:

Trisha Greenhalgh: How to read a paper the basics of evidence-based medicine

Caroline De Brún & Nicola Pearce-Smith: Searching skills toolkit : finding the evidence

Iain K. Crombie: The pocket guide to critical appraisal : a handbook for health care professionals

Ben Yudkin: Critical reading : making sense of research papers in life sciences and medicine

How to document sources

(extract from @LangLangC's now deleted answer)

The internet never forgets!

This is a myth. Links change, pages vanish, whole domains might evaporate or worse, change hands to owners doing the opposite of what was once there. Not all of them are archived at archive.org. sometimes nothing seems to have changed but the content of a page is changed in subtle ways. Wikipedia for example is an evolving project, pages are dynamic in their content. It is justified to call that source unstable.

Unless very basic things are referred to Wikipedia links should point to a specific version of the page.

But more importantly:

Even if a "Good Source" is not easily accessible, and you are encouraged to use alternatives when possible, then there is one way to improve on that situation that should also apply to most other citations.

Example being:

Primary literature articles behind pay walls

If you have access, then retype or copy and paste quotes from your sources. It will be a legal challenge as well as unpractical to do that with whole articles or whole books.

But the dosage makes the poison. Used sparingly this is used effectively. The core concepts or crucial statements from a primary source behind a paywall or from a printed book are even more conveniently to check then. That part quoted is more protected from link-rot and this kind of redundancy increases robustness all around.

Using short but crucial quotes improves every source.

  • 4
    This is nit picky, but when using Wikipedia, the reference supporting a statement should be read. I have found too many instances when a wiki writer misrepersented the source or the source was about something altogether different! Wiki is written by whoever wants to write it. Web MD also provides sources, which should be looked at, as does the Mayo site and the Cleveland clinic site. Commented Sep 20, 2017 at 17:26
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    Edited, thanks!
    – DoctorWhom
    Commented Sep 21, 2017 at 1:26
  • 1
    What about source monitoring regarding quality? There are things called "junk-science" and how do we address that, even among the (usually) 'excellent sources'? Commented Sep 23, 2017 at 19:36
  • @LangLangC Using comments, flags and down votes. Every major journal has some bad articles sneaked in there. We can educate answerers of that.
    – Narusan
    Commented Sep 23, 2017 at 20:07
  • Seems like a line of defence one step too late – if it is not in the 'FAQ or sth' that 'appeals to authority' and blindly trusting certain sources are nod good. Evaluation of sample size, reach, effect size, design quality, theoretical framework etc. are all and always to be considered. Haven't started on statistics yet… Commented Sep 23, 2017 at 20:17
  • Rigorous fact checking is encouraged.
    – DoctorWhom
    Commented Sep 23, 2017 at 22:14
  • @Narusan-in-coma Yes definitely, but how do I do that? I can't seem to find the option...
    – DoctorWhom
    Commented Oct 10, 2017 at 1:28
  • @Narusan-in-coma lol I apparently started to ignore that little button at some point and had to re-discover it
    – DoctorWhom
    Commented Oct 12, 2017 at 3:15
  • Maybe you could link in the reliable sources question into this answer somewhere? Commented Apr 11, 2019 at 8:20
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    All of the links for help for reading, understanding and interpreting scientific and medical papers" are broken.
    – MattDMo
    Commented May 30, 2021 at 17:05

What if the references aged and are obsolete. Will we require numbred references. what style one should use? If you require references, where is the style guide?

  • I don't think APA or AMA etc are going to be required, just a link or other way to find the info from which the answer comes
    – DoctorWhom
    Commented Jun 7, 2019 at 3:03
  • @DoctorWhom - I agree with you but to a point. If a question or answer is printed for future reference in paper notes and the content is links only, the references in the question and answer are lost as the link content is not printed. Psychology.SE prefers a references section in APA format (or similar - with author and year at the beginning of each citation) and that rectifies the problem. Commented Aug 4, 2019 at 10:13

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