Wikipedia:When can you cite a preprint invoking expert SPS?

“ Self-published expert sources may be considered reliable when produced by an established subject-matter expert, whose work in the relevant field has previously been published by reliable, independent publications. ”

This passage from WP:EXPERTSPS is often used to justify the inclusion of non-reliable/non-peer reviewed sources on the basis that they are written by experts. The most common of which being blog posts and preprints. The argument is that since these are experts, these sources become reliable. This would mean nearly all preprints are reliable sources because most preprints are written by experts.

The reality is that peer reviewed articles from experts often contain errors. Clearing peer review just means you get to be part of the scientific debate. Preprints, or other preliminary/non-peer reviewed results, contain even more errors because one of the goals of peer review is to find those errors. Experts make mistakes all the time, and Wikipedia should not try to get ahead of the process just because one expert, or even a team of experts, is claiming a certain discovery ahead of publication.

So when can you invoke an SPS as a reliable source? The short of it is that an SPS is acceptable for routine, non-controversial claims, but that novel claims must still, at the very least, clear the higher bar of peer-review.

When can you invoke SPS?

Routine claims

Non-peer reviewed sources, such as preprints, are perfectly acceptable to sources routine, non-novel claims, such as where a certain person is employed, or some background information that is not central to the paper. For example, using the preprint arXiv:2412.10366, whose abstract reads

“ We study realistic models predicting primordial black hole (PBH) formation from density fluctuations generated in a first-order phase transition. We show that the second-order correction in the expansion of the bubble nucleation rate is necessary for accurate predictions and quantify its impact on the abundance of PBHs and gravitational waves (GWs). We find that the distribution of the fluctuations becomes more Gaussian as the second-order term increases. Consequently, models that predict the same PBH abundances can produce different GW spectra. ”

We could use that source to support uncontroversial statements like

• Marek Lewicki is an astrophysicist working at the University of Warsaw.<ref>arXiv:2412.10366</ref>
• Primordial black holes are a candidate for dark matter.<ref>arXiv:2412.10366</ref>

Because both are routine statements. Other sources might be preferable, like the University of Warsaw staff website, or a book dedicated to primordial black holes, but WP:V and WP:SPS are both met.

Novel claims

However, we could not use that same source for the novel claim that

• Models that predict the same primordial black hole abundances can produce different gravitational wave spectra.<ref>arXiv:2412.10366</ref>

Why? Because that's the new result undergoing evaluation. Any sort of mistake could have happened to jeopardize that conclusion, ranging from

• Computer code mistakes, or unintentional bugs (e.g. writing 'y = mx - b' in code when 'y = mx + b' was meant)
• Flawed assumptions (e.g. assuming all the fish detected in a river are trouts when there's a mix of trout and salmon)
• Flawed statistical analysis / error analysis (e.g. thinking a result is 15.5±0.5 m when it really is 15.5±2.8 m)
• Modeling mistakes (e.g. assuming cows are spherical, when a cubic model would be more appropriate)

Thus if a team of experts is claiming a discovery ahead of peer-review, Wikipedia cannot say something like

The gravitational constant, G, has been determined to be 6.674305±0.000012 N⋅m²/kg².<ref>Smith, J. ... (preprint).</ref>

as if this was an established fact, or even

On July 23, a collaboration from the University of Foobar has determined the gravitational constant, G, to a new precision of 6.674305±0.000012 N⋅m²/kg², improving the accuracy by over 10 times.<ref>Smith, J. ... (preprint).</ref>

as if the determination was recognized by the scientific community.

At most, Wikipedia can say something like

On July 23, a collaboration from the University of Foobar claims to have determined the gravitational constant, G, to a new precision of 6.674305±0.000012 N⋅m²/kg², improving the accuracy by over 10 times.<ref>Smith, J. ... (preprint).</ref>

which is simply that a certain group made a certain claim, and takes no position on whether or not the claim is valid.

However, other considerations, like WP:DUE, WP:NOTNEWS, etc., must still be met. Oftentimes, the answer is simply to wait until the claim appears in a reliable peer-reviewed venue.

Documents hosted on preprint repositories that are not preprints

Note that the above apply only to preprints, which is a term that apply to the versions of a paper prior to formal publication. It is not intended to be an authoritative resource, but rather one which is still in need of peer-review. They usually uploaded to established priority of discovery, but also to get feedback from the academic community, leading to an improved paper, revised arguments, correction of mistakes, etc...

A paper being on a preprint repository like arxiv is not a guarantee that it is a preprint. Several uploads are simply lecture notes, pedagogical material, or technical reports. Those are perfectly allowed under WP:EXPERTSPS.

For example

• arXiv:hep-ph/0511217 – A distilled version of a invited lecture given at the SLAC Summer Institute in 2005. This is clearly a source allowed by WP:EXPERTSPS. It is authored by an acknowleged expert in the field (only distinguished scholars are invited to give lectures), and puts no novel results forward. It summarizes the state of the field (as of 2005).
• arXiv:2101.04168 – A compilation of the first 50 issues of John C. Baez's This Week's Finds of Mathematical Physics. These are as reliable as the original publication, authored by an acknowleged expert in the field (i.e. John C. Baez).
• arXiv:2211.07787 – A translation of a famous paper on quaternions by Olinde Rodrigues, translated by Richard Friedberg a theoretical physicist with an extensive background in mathematics. The paper was originally published in Journal de Mathématiques Pures et Appliquées, should be cited as the original source, but the translated paper can be cite alongside, for convenience to non-English speakers.

See also

• WP:USESPS
• WP:RS
• WP:SPS
• WP:RSE
• WP:MEDRS
• WP:SCIRS
• WP:EXCEPTIONAL