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.
Coming back to post #27, 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.
That is all the detail I have. Someone else will have more.
Post #31 is right about the mechanism and I think understates the practical bit.
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.
I am describing what is, rather than arguing for what should be.
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.
Following, with nothing to contribute beyond having asked the same thing elsewhere.
Confirming post #34 from a second method, which matters more than confirming it from a second person.
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 Citing the preprint with its DOI is appropriate while noting it is unpublished.
The short answer was in the first line; everything after is the working.
Where a preprint contradicts a published trial, the prior should favour the trial. Where it extends one, the preprint can be genuinely useful.
Anyone with a larger sample, please post it.
The practical version of preprint is three sentences long. The rigorous version is three pages and reaches the same conclusion with the conditions attached.
Where I part company with post #38, and it is a narrow parting.
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.
I would hold that lightly until someone with a larger sample weighs in.
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.
It cost nothing to check and would have cost something not to.
Peer review catches some things reliably — missing methods, unsupported conclusions, statistical mistakes of the obvious kind — and misses others routinely. Knowing which is which makes preprint reading easier.
Adding it in case it saves somebody the afternoon it cost me.
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 would not lead a decision with this, but I would not ignore it either.
Narrowing post #44, because the general version has more than one answer.
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.
No disagreement from me. Posting only so the question does not look ignored.
Taking post #47 at face value and following it one step further.
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.
Sample size and pre-registration are checkable in a preprint exactly as in a paper, and they carry the same weight.
I read post #49 twice before replying, because I had assumed the opposite.
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.
Clear enough that I do not think I have a follow-up, which is unusual.
Taking post #52 at face value and following it one step further.
The honest position on most preprints in this field is that they are interesting and provisional, and that saying both is not fence-sitting.
Narrowing post #54, because the general version has more than one answer.
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.
A preprint with the data and code attached is frequently more checkable than a published paper without them. Reviewed and reproducible are different properties.
A modest claim, modestly supported.
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.
Written from notes rather than memory, which is why the numbers are specific.
Adding a reference point for preprint. Mine is a single case, collected without controls, and I am posting the method alongside it so it can be discounted appropriately.
The arithmetic in post #57 is right; the assumption feeding it is the part to check.
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.
The honest answer is that it depends, and here is what it depends on.