Sample size: how many participants are needed in a cohort study?

BMJ 2014; 349 doi: (Published 12 November 2014) Cite this as: BMJ 2014;349:g6806

This Endgames article (BMJ 2014;349:g6557, doi:10.1136/bmj.g6557) contains an error in the last sentence of the third paragraph of the answers section. This sentence should have read: “An improvement in precision requires an increased sample size (b is true); for example, to have precision within three percentage points for the estimated prevalence of 20% would require a sample size of 683 [not 1537, as was published] participants.”


Cite this as: BMJ 2014;349:g6806

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