Design and Analysis in Nutrional and Physiological Experimentation

Planning, executing, analyzing, and interpreting experiments is part of research in nutrition and physiology.The principles and techniques of these endeavors have been recorded in an extensive literature.My objective is to review the basics of this enterprise and illustrate aspects that are widely misunderstood.The examples are from recent research reported in the Journal of Dairy Science.However, direct references to the original articles will not be cited, and their identity will be masked further by changing names of treatments and other small details.My intention is to point out some common mistakes 1 find widely repeated in the literature, not to criticize a few authors.The authors are only partly at fault.They often have been miseducated by teachers of statistics like me and misguided by well-meaning reviewers of their work.Nor is the main purpose to emphasize errors in this journal, for its standards are higher than most comparable ones publishing scientific research.However, I believe improvements can be made that will benefit your research, and to make the case I want to use real examples from types of investigations that are familiar. Fundamentals of Designed ExperimentsThe investigations I call experiments include several ingredients that are absent in more general observational studies.Experiments are works that utilize experimental units, entities usually assigned by the experimenter to treatments.The treatments are conditions controlled and varied by the experimenter.Often treat-