Principles: The need for better experimental design

Many experiments could be improved with better experimental design and statistical analysis. Badly designed experiments can lead to incorrect conclusions and wasted time and scientific resources. Such experiments are unethical if they involve animals or humans. Good experimental design requires clearly defined objectives and control of the major sources of variation. In this article, a small mouse experiment involving the response of a liver enzyme to the administration of an antioxidant is used to illustrate some important design concepts such as the control and partitioning of sources of variation using factorial and randomized block designs and the estimation of appropriate sample sizes. Scientists clearly need better training in experimental design with better access to consultant statisticians for more complex situations.