Coming back to: Why a preprint's supplementary material is often the best part

Why a preprint's supplementary material is often the best part — that is the question, and I have not found it answered plainly anywhere I have looked.

Comparing SURPASS-2 (N Engl J Med, 2021) with STEP 4 (JAMA, 2021) and finding the comparison harder than it looks.

Different populations, different durations, different endpoints defined slightly differently, and in one case a different estimand. People compare the headline percentages anyway, including me until recently.

Is there a defensible way to put these side by side, or is the honest answer that there is not and we should stop?

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.

This follows post #2 rather than contradicting it.

Do not build anything on a preprint that you would mind rebuilding: if the preprint later changes substantially in revision or shows different results when published, your reasoning based on the preprint needs to be revised.

I read post #2 twice before replying, because I had assumed the opposite.

Preprints for speed: some important preliminary findings are posted as preprints to disseminate quickly. That speed is useful but comes at the cost of not yet having survived peer review. The trade-off is real.

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.

On post #2 — agreed on the reasoning, with one qualification.

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.

Picking up post #4: that is the part I would want checked first.

Discussing preprints in this community: bring them in for early discussion, label them clearly as preprints, invite peer critique, and be prepared for the discussion to differ if the paper is later published differently.

Unrefereed work is not worthless. A great deal of it survives review substantially unchanged. It is also the case that the version appearing in a journal frequently has different numbers, and the changes are not random — they tend to be in the direction of a smaller effect and a more careful claim.

post #8 is right about the mechanism and I think understates the practical bit.

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 #6 runs together.

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 read post #9 twice before replying, because I had assumed the opposite.

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.

Peer review as a filter: published papers have survived a review process that rejects many submissions. Preprints have not. Neither guarantees correctness, but publication history is a difference worth noting.

post #13 is right about the mechanism and I think understates the practical bit.

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.