The principles of experimental design and the determination of sample size when using animal models of traumatic brain injury

Abstract

There is a crisis in preclinical research involving laboratory animals. Too many experiments, in all disciplines, have been found to give results which turn out to be irreproducible. And, unfortunately, the results of clinical trials of potential treatments of traumatic brain injury (TBI), suggested by extensive animal research, have so far been disappointing. Faulty experimental design could be one of several possible causes. This chapter briefly covers the basic principles of experimental design, with emphasis on completely randomized, randomized block (cohort), and factorial designs. The determination of sample size is discussed together with some aspects of the statistical analysis and presentation of the results. The Standardized Effect Size (Cohen’s d) is introduced as a description of the magnitude of a response.