The Importance of Replication in Wildlife Research

Abstract:  Wildlife ecology and management studies have been widely criticized for deficiencies in design or analysis. Manipulative experiments-with controls, randomization, and replication in space and time-provide powerful ways of learning about natural systems and establishing causal relationships, but such studies are rare in our field. Observational studies and sample surveys are more common; they also require appropriate design and analysis. More important than the design and analysis of individual studies is metareplication: replication of entire studies. Similar conclusions obtained from studies of the same phenomenon conducted under widely differing conditions will give us greater confidence in the generality of those findings than would any single study, however well designed and executed.

Key words:  control, experiment, metareplication, observational study, pseudoreplication, randomization, replication, sample survey, science

Table of Contents

• Introduction
• Caution About Causation
• Manipulate, If You Can
• Controls
• Randomization
• Replication
• Other Levels of Replication
• More on Metareplication
• Conclusions
• Literature Cited

Acknowledgments

I am grateful to the many statisticians and biologists who have taught me so much as teachers, colleagues, or students. B. R. Euliss helped prepare the manuscript. Special thanks for valuable comments on this manuscript to D. R. Anderson, L. A. Brennan, K. P. Burnham, L. L. Eberhardt, S. H. Hurlbert, W. P. Kuvlesky, Jr., J. D. Nichols, M. R. Riggs, G. A. Sargeant, A. Stewart-Oaten, and an anonymous referee, all of whom nonetheless deserve to be held blameless for remaining faults. Thanks also to L. A. Brennan for the invitation to write the paper.