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Topic summary

Random versus fixed effects: choosing rather than defaulting — a second dataset

This is a generated summary. It shows the 9 most-liked posts from a topic of 107, 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.
BS
buffer_shiftTL1Member24 Jan 2025#4
st.diallo, post #3: 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. Go to post

Funnel plots: a plot of study effect size versus sample size that helps detect publication bias. If small studies are missing on the negative side, the funnel is asymmetrical.

27 likes in reply to #3 18mo
G
GEldridgeTL3Regular27 Jan 2025#12

post #11 answers the question as asked. The question underneath it is different.

Pooled estimates and heterogeneity: when trials differ in population, duration, or comparator, a pooled estimate answers a question that no individual trial asked. High heterogeneity means effects genuinely differ across studies. The pooled number is an average of things that should not have been averaged.

27 likes 18mo
CV
ca.vermeulenTL2 Moderator28 Jan 2025#19

On post #15 — agreed on the reasoning, with one qualification.

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.

28 likes 18mo
IO
i.oseiTL2 Moderator31 Jan 2025#32

Picking up post #29: that is the part I would want checked first.

Funnel plots: a plot of study effect size versus sample size that helps detect publication bias. If small studies are missing on the negative side, the funnel is asymmetrical.

32 likes 18mo
VD
vial_deskTL3Regular3 Feb 2025#48
z.szabo, post #28: Publication bias: what did not get published? Small studies with negative results are less likely to be published than large studies with positive results. A forest plot with only large studies on the positive end is a red flag for unpublished small negative studies. Go to post

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.

30 likes in reply to #28 18mo
KD
k.dahlbergTL2 Moderator6 Feb 2025#64

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.

32 likes 18mo
IB
i.balogunTL2 Moderator7 Feb 2025#72

This follows post #69 rather than contradicting it.

Pooled estimates and heterogeneity: when trials differ in population, duration, or comparator, a pooled estimate answers a question that no individual trial asked. High heterogeneity means effects genuinely differ across studies. The pooled number is an average of things that should not have been averaged.

30 likes 18mo
I
IRenaudinTL2Member9 Feb 2025#79
b.teixeira, post #38: post #37 is right about the mechanism and I think understates the practical bit. 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… Go to post

Why forest plots are more informative than pooled numbers: they show the variation across studies, which tells you whether the effect is consistent or heterogeneous. A narrow confidence interval around a meaningless centre is less useful than a wider interval that shows real differences.

31 likes in reply to #38 18mo
AV
ai.vukovicTL2 Moderator10 Feb 2025#85
b.osei, post #62: On post #58 — agreed on the reasoning, with one qualification. 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. Go to post

This follows post #82 rather than contradicting 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.

29 likes in reply to #62 18mo

Read the full topic (107 posts)

Moved from Preprints by s.leclerc. Category placement is not obvious from outside and getting it wrong is expected. This topic will get better answers here. The move is recorded in the public log citing R7.

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