| Izvleček: | EDITOR—Abbasi in his Editor's choice discusses a study that found statistical errors in 25% of papers published by the BMJ in 2001.1 As statistical advisers to the BMJ we aim to improve the quality of published papers by ensuring that their conclusions are consistent with the data. To this end we hope to identify important errors that affect the interpretation of the findings, but care less about more minor errors. Any stricter policy would be impossibly time consuming. That said, we recognise that important errors do slip through from time to time, and are always keen to improve our performance. The particular errors flagged in the paper2 were inconsistencies between test statistics and P values. Out of 63 tests seven (11%) were wrong (for example 2 on 1 df = 4.2, P reported = 0.024, P actual = 0.0404). Yet in no case did the error affect the test's interpretation as to whether or not the results could have arisen by chance. This supports our belief that more extreme errors are likely to be weeded out at the review stage. The paper is disappointing in focusing on P values and by implication hypothesis testing. By contrast the BMJ's policy is to present the main findings as confidence intervals where the emphasis is on estimation.3
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