Topic summary

Second pass at: A pooled estimate that changed when one trial was added

Evidence › Meta-analyses effect size risk of bias publication bias meta-analysis Wiki

This is a generated summary. It shows the 5 most-liked posts from a topic of 31, 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.

f.laurentTL2 Moderator5 May 2026#1

Community wiki post. Any member at trust level 3 or above can edit this post; every edit is recorded. Last edited by n.rowntree on 9 Jun 2026.

9 Jun 2026 — n.rowntree: Corrected an arithmetic slip in the second example.

Editors: n.rowntree, bench_notes, buffer_sheet

On the subject in the title: Second pass at: A pooled estimate that changed when one trial was added Working notes rather than a conclusion.

Session topic: SELECT (N Engl J Med, 2023). Please read it before posting; the discussion is much better when everyone has.

The question I would like us to start with is what the trial set out to estimate, rather than what it found. Once that is on the table we can talk about whether the design could have answered it, and only then about the numbers.

Specific things I would like covered: the population and how far it generalises, how discontinuation was handled, whether the comparator was a fair one, and what the absolute rather than relative effect looks like.

I will summarise at the end and the summary will feed the relevant digest page.

39 likes 3mo

r.mensahTL2 Moderator14 May 2026#5

Picking up post #2: that is the part I would want checked first.

Number needed to treat from a meta-analysis: can be computed from the pooled estimate if the baseline risk is specified. More interpretable than pooled relative effects.

29 likes 2mo

j.ivaturiTL2 Moderator28 May 2026#15

Sensitivity analysis: the authors re-run the meta-analysis excluding studies one at a time, or by quality, to see whether the pooled estimate changes. Robust results stay similar even when individual studies are excluded.

29 likes 2mo

j.vogelTL2 Moderator4 Jun 2026#21

post #20 answers the question as asked. The question underneath it is different.

Study quality and weighting: some meta-analyses weight all studies equally; others weight by study size or study quality. The choice affects the result and should be stated and justified.

28 likes 2mo

o.abrahamsenTL3Regular14 Jun 2026#30

Inclusion and exclusion criteria: a meta-analysis is only as good as its inclusion criteria. If the criteria are too broad, apples and oranges get pooled. If they are too narrow, the meta-analysis answers a overly specific question.

29 likes 1mo

Read the full topic (31 posts)

This topic was referenced in

Prediction intervals and why they are more honest than confidence intervalsEvidence › Meta-analyses · 25 replies
[2026 update] Heterogeneity as information rather than as a nuisanceEvidence › Meta-analyses · 4 replies
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