Statistical analysis features in most of the papers published in medical journals and while clinical researchers need a basic knowledge of research methodology, they do not necessarily need to be expert in statistical techniques. The presentation will begin with a rapid overview of the training and skills of the statistical consultant and the his/her role in the research group. Then, from the description of some common errors in medical research, reasons will be given for involving such experts in the research project; many issues will be presented showing how a statistician can help: choice of the design, questionnaires, displaying data, choice of statistical analysis and finally sample size and power calculations. Lastly emphasis will be given to the need to consult the statistician early in the planning of a study and not just in the final analysis of the data once they have been collected.