Authors' replyBMJ 1996; 313 doi: https://doi.org/10.1136/bmj.313.7050.166b (Published 20 July 1996) Cite this as: BMJ 1996;313:166
- Martin Prince,
- Anthony Mann,
- Robert Blizard,
- Anne Bird
- Lecturer in psychiatry Professor of epidemiological psychiatry Institute of Psychiatry, London SE5 8AF
- Lecturer in statistics Consultant psychiatrist Royal Free Hospital, London NW3 2QG
EDITOR,—Strictly speaking, it is never possible to prove a null hypothesis. However, lack of support for rejecting a null hypothesis is an important finding in a study in which treatment has been randomly allocated to over 2500 subjects. This sample size would have given us 99.9% power to detect a difference in the rate of change in the scores obtained in the paired associate learning test of >/=0.1 point a year between treatments.
Although it is desirable to test multiple cognitive domains, there are …
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