Multiple comparisons: if a paper reports many outcomes, the chance of a spurious association by random chance is real. Pre-specification of primary outcomes matters and secondary analyses are weaker evidence.
Immortal time bias in a claims-database study posts 31–35
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Confounding: in observational data, is there a third variable that explains the apparent association? In randomised data, randomisation should balance unknown confounders, though known confounders can be adjusted for.
This follows post #30 rather than contradicting it.
Publication bias: a single published positive trial is weaker evidence than multiple published trials with consistent results. Asking whether there are unpublished negative trials is a fair critical question.
I read post #32 twice before replying, because I had assumed the opposite.
Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.
The correction was fair and I had been repeating something I had not checked carefully enough.
This topic was referenced in
- Critiquing an observational claim about a class effect — one year onEvidence › Study critique · 9 replies
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