Why a preprint's supplementary material is often the best part

Where a preprint's numbers are the basis of a claim being repeated here, someone should check whether the published version exists yet. That check is nearly always overdue.

Say it is a preprint in the first line rather than the last. Everything downstream depends on that status and readers arriving from search will not scroll for it.

Adding it because I spent an afternoon working it out and nobody should have to twice.

This is the sort of exchange that makes the archive worth searching.

I had written a reply contradicting post #16 and deleted it. Here is what survived.

Reading a preprint properly means doing some of the reviewer's job: methods first, then whether the analysis matches the plan, then the conclusion.

Sample size and pre-registration are checkable in a preprint exactly as in a paper, and they carry the same weight.

None of the above is medical advice and I am not qualified to give any.

This is the first time the answer has come with its own limits attached. Appreciated.

Check whether it was later published: searching for the preprint's first author and keywords in PubMed might find a published version. The published version is the stronger citation if it exists.

A qualification I should have led with rather than closed on.

This follows post #21 rather than contradicting it.

Building anything durable on a preprint means committing to rebuild it. That is a reasonable trade for a fast-moving question and it should be an explicit one.

Coming back to post #21, because the follow-up matters more than the original answer.

Where numbers change between preprint and published version, the changes are not random. They tend toward a smaller effect and a more carefully hedged claim.

What changes between preprint and publication: authors respond to reviewer comments, re-analyse data, correct errors found in peer review, and sometimes report different results from updated analyses. The published version is not the same as the preprint.

I have separated what I observed from what I concluded, which does not always happen.

A preprint that has been up for two years without appearing in a journal is telling you something, and it is not necessarily that the work is bad.

That is the version I would defend. It is not the version I started with.

Version numbers on a preprint server matter. Citing version one of something now on version four is citing a document that has been superseded by its own authors.

Flagging that the sources on this are thinner than the confidence in the thread suggests.

Reading back through, this was answered upthread and I missed it. My fault.

Confirming post #25 from a second method, which matters more than confirming it from a second person.

Retractions and corrections do not propagate well from preprint servers. A citation that was fine when made can quietly become wrong.

Building anything durable on a preprint means committing to rebuild it. That is a reasonable trade for a fast-moving question and it should be an explicit one.

Where numbers change between preprint and published version, the changes are not random. They tend toward a smaller effect and a more carefully hedged claim.

Noting that I have skin in this question and have tried to discount for it.