Critical features of veterinary field trials

The field trials of drug and vaccine efficacy published in The Veterinary Record in the last five years were reviewed. The reviewers showed that in addition to some excellent studies with clear and concise design and analysis, there was a considerable lack of detail in reporting the method of allocation of animals to treatments, whether groups of animals or individual animals were allocated to treatments, whether the trials were blind, and a lack of formal analysis of the results. A considerable number of studies had problems with clustering of data. Some critical features of the design and analysis of a clinical field trial are discussed and improvements are proposed.