This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
I would keep preprint and the decision it usually gets used for separate in this thread. They are related and they are not the same question, and merging them is why the last one went badly.
Server repositories: medRxiv for medicine, bioRxiv for biology. Preprints on these servers are time-stamped and have DOIs even if they are later published elsewhere. Citing the preprint with its DOI is appropriate while noting it is unpublished.
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 Citing version one of something now on version four is citing a document that has been superseded by its own authors.
Happy to expand any of that if it is the useful part.
On post #60 — agreed on the reasoning, with one qualification.
Screening on a preprint server is minimal and is not review. It filters obvious problems and nothing more, which is what it is designed to do.
Scoping that to what I have actually seen rather than what I have read.
Post #63 is right about the mechanism and I think understates the practical bit.
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.
That is my reading. Someone else read the same page differently and was reasonable.
Building on post #66 rather than restating it.
Always label it as a preprint in any discussion. A preprint is not a published trial and it is not settled knowledge. Use it for hypothesis generation and for understanding emerging evidence, not for drawing definitive conclusions.
If the premise is wrong, everything after it is decoration.
Post #68 put the caveat in the right place and I want to underline it.
How to cite a preprint: author last name, first initial, et al. Title. Server name [preprint]. Posted date. Doi. Include the server name and note that it is a preprint.
The claim is narrower than it sounds, and deliberately so.
Saving this. It is the version I will quote when the question comes round again.
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.
Worth separating two things that post #72 runs together.
If you cite a preprint in a maintained document here, the convention is to label it in the sentence and to note the check date. The document review will catch the update.
I am reporting what happened, not recommending it.
This follows post #72 rather than contradicting it.
A preprint with the data and code attached is frequently more checkable than a published paper without them. Reviewed and reproducible are different properties.
I would be interested in a counterexample if anyone has one.
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.
Narrowing post #75, because the general version has more than one answer.
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.
That is the version I use. It may not be the version that is correct.
Post #75 and I disagree about the size of the effect, not about the direction.
Adding the boring version of preprint, because the interesting version keeps getting posted and the boring one is usually right.
Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.
Before the thread moves on from preprint — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from an n of four and from an n of four hundred.
I had written a reply contradicting post #75 and deleted it. Here is what survived.
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.
Worth reading the earlier posts in this thread before acting on mine.
Confirming post #79 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.
That is one dataset and I would not build a rule on 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.
This follows post #80 rather than contradicting it.
Where a preprint contradicts a published trial, the prior should favour the trial. Where it extends one, the preprint can be genuinely useful.
I have left out the parts I could not verify.
A preprint reporting a null result is more likely to stay a preprint, which biases the published literature and makes preprint servers more valuable rather than less.
Reading it again, the caveat matters more than the finding.
Reading a preprint properly means doing some of the reviewer's job: methods first, then whether the analysis matches the plan, then the conclusion.
Everything in post #82 holds. The case it does not cover is the one I have.
I read the earlier replies on preprint twice before writing this, because I had assumed the opposite and wanted to be sure I was disagreeing with what was said rather than what I expected.
Marking my place. If it changes for me I will come back and say so.
Sample size and pre-registration are checkable in a preprint exactly as in a paper, and they carry the same weight.
The arithmetic in post #88 is right; the assumption feeding it is the part to check.
Server repositories: medRxiv for medicine, bioRxiv for biology. Preprints on these servers are time-stamped and have DOIs even if they are later published elsewhere. Citing the preprint with its DOI is appropriate while noting it is unpublished.
It is worth stating the boring hypothesis before the interesting one.