Topic summary

Second pass at: What pooling buys you and what it destroys

Evidence › Meta-analyses risk of bias meta-analysis heterogeneity

This is a generated summary. It shows the 5 most-liked posts from a topic of 37, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.

a.kravchenkoTL29 Jan 2026#8

Coming back to post #6, because the follow-up matters more than the original answer.

Pooling buys is well covered in the tag pages, and the older discussions are better than the recent ones because they were argued out properly. Worth twenty minutes before adding to this one.

28 likes 7mo

sterile_fileTL3Regular24 Jan 2026 · edited#12

Speaking only to pooling buys as I have actually seen it, rather than as it is usually described: the effect is real, it is smaller than the thread suggests, and the variance between people is larger than the effect.

33 likes 6mo

v.milanoviTL3Regular7 Feb 2026#16

e.roos, post #10: Grateful for the specificity. Vague answers to this question are what sent me looking. Go to post

Practical note on pooling buys: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow.

25 likes in reply to #10 6mo

k.salinasTL25 Mar 2026#24

Practical experience of pooling buys, offered as one case with the conditions stated, not as a general finding. Conditions first, because they are what make it interpretable.

25 likes 5mo

sleep_logTL2Regular26 Mar 2026#31

c.castellanos, post #2: On the opening post — agreed on the reasoning, with one qualification. What I would want before treating pooling buys as settled: the method, the sample, and whether anyone tried to find the opposite result. Two of the three are usually missing. Go to post

Post #27 put the caveat in the right place and I want to underline it.

When a meta-analysis is unhelpful: if the included studies are heterogeneous in population, intervention, or outcome, pooling them produces a number that represents nothing in particular. Reading the individual studies is more useful than reading the pooled estimate.

Not the answer, but possibly the question that gets there.

32 likes in reply to #2 4mo

Read the full topic (37 posts)

This topic was referenced in

What pooling buys you and what it destroysEvidence › Meta-analyses · 83 replies
Individual participant data versus aggregate dataEvidence › Meta-analyses · 34 replies
Random versus fixed effects: choosing rather than defaulting — a second datasetEvidence › Meta-analyses · 106 replies

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