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Believability of relative risks and odds ratios in abstracts: cross sectional study

BMJ 2006; 333 doi: https://doi.org/10.1136/bmj.38895.410451.79 (Published 27 July 2006) Cite this as: BMJ 2006;333:231

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A statistical quibble

Dr Gotzsche has written an excellent article. I just wish
to point out one minor statistical flaw. Some abstracts
seemed to be criticized for using the chi-square test
without continuity correction. The continuity correction
is an attempt to make the Pearson chi-square test behave
like Fisher's exact test. As Fisher's test is
conservative (i.e., P-values from it are too large) this
is not a good goal, and the uncorrected chi-square
statistic actually provides more accurate P-values in
general. See for example Agresti A, Stat in Med 20:2709;
2001.

Competing interests:
None declared

Competing interests: No competing interests

23 August 2006
Frank E Harrell
Chair, Department of Biostatistics
Vanderbilty University School of Medicine