Commentary on 'Designs for dose-escalation trials with quantitative responses'.

Bailey (Statist. Medi 2009; this issue) puts the focus on efficiency in dose-finding studies and shows that some quite simple modifications to much current experimentation can lead to significant efficiency gains. Efficiency has not been the main focus of interest in this field, in particular when dealing with situations requiring other than healthy volunteers. Dr Bailey's results are important, both in theory and in practice and also raise the question as to what ought to be the guiding principle to statistical workers in this field. Safety, although escaping any simple definition, has mostly guided experimentation in dose-finding studies; one reason being that the concept is one on which clinicians and statisticians can come to some broad agreement. Finding such agreement may still be the single major difficulty in these studies, alongside the establishment of criteria that all of the scientists involved believe are the most appropriate and useful ones.