The correct application of appropriate statistical methods in clinical trials is essential for deriving valid conclusions. This paper covers a number of the key principles, with particular relevance to studies in herpes zoster. The distinct roles of the P-value and the confidence interval are investigated and their use in the assessment of the equivalence of two treatments evaluated. The principle of intent-to-treat is discussed and is seen to be vitally important for obtaining correct conclusions. The definition of end-points in the assessment of pain in herpes zoster is controversial; it is argued here that the only valid approach is to consider the time from start of treatment to complete cessation of all pain. Finally, methods for the evaluation of time to event data are explained in general terms, and particular drawbacks relevant to herpes zoster are discussed.
