Dear all,
A phase II clinical trial is to find out whether a drug changes one of the
markers in cancer patient. The expression of the marker will be in 4
categories negative, weak, moderate and strong. The investigators expect some
changes (downwards) in the markers, say 30% of the patients, before and after
the treatment, i.e. from strong to moderate, from moderate to weak or from weak
to negative. How can I calculation the sample size for this kind of trial?
Any suggestions or advice are highly appreciated.
Thank you very much in advance.
Jenny
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