Montori, Victor M., M.D. wrote:
> Dear list,
> Studies can be small and well powered or small and underpowered. The second
> type as you correctly state suggests carelessness in designing the study.
Victor / listActually the issue that I struggle with regarding power as a
quality issue is precisely whether or not it does (necessarily) suggest
carelessness, or certainly carelessness that should be generalised to other
aspects of the design. There are, as you point out, many reasons why large
samples might not be available. The opportunity to prospectively plan data
pooling on a national / international scale is just not always there, although
I agree that it should be aspired to.
What we are left with is the question as to whether or not is complete
ignorance better than some reduction in uncertainty from a small trial (even if
the reduction is marginal), whether it is ethically justified to impose on
patients for small knowledge gains and just how else to assess effectiveness
when sample sizes must be small.
My uncertanty remains!
Peter
--
Peter Griffiths
Lecturer, Research in Nursing Studies Section
Florence Nightingale Division of Nursing and Midwifery
King's College London
Waterloo Rd
London, UK
SE1 8WA
+44 171 872 3012 (DDI)
+44 171 872 3219 (Fax)
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