1 Nuffield Department of Obstetrics and Gynaecology,University of Oxford, John Radcliffe Hospital, Headington,Oxford OX3 9DU, UK, 2 Research Centre for ReproductiveMedicine, Department of Obstetrics and Gynaecology,National Women's Hospital, Auckland, New Zealand and 3 School of Biological and Molecular Sciences, Oxford BrookesUniversity, Headington, Oxford OX3 0BH, UK
Dear Sir,
We wish to report errors in our paper published last year (Muttukrishnaet al., 2000). We have recently discovered that the web-based calculator (http://cebm.jr2.ox.ac.uk/docs/2x2table.html) uses an incorrect formula to calculate confidence intervals for sensitivity. We present revised Tables III and IV
below. Confidence intervals were recalculated using the software Confidence Interval Analysis (2000). This resulted in the same point estimates, but wider confidence intervals and minor alterations to post-test probabilities.
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Notes
4 To whom correspondence should be addressed at: Department of Obstetrics and Gynaecology, Royal Free-UCL Medical School, 8696 Chenies Mews, London WC1E 6HX, UK
References
Altman, D.G., Machin, D., Bryant, T.N. and Gardner, M.J.(2000) Statisticswith Confidence. 2nd Edn, BMJ publications, UK.
Muttukrishna, S., North, R.A., Morris, J. et al. (2000) Serum inhibin A and activin A are elevated prior to the onset of pre eclampsia. Hum. Reprod., 15,16401645.