The Possible Impact of Observer Bias on Some Avian Research
American Ornithologists' Union
Observer-expectancy bias is systematic error produced in observational data by an observer's expectations or wishes. The error is strongly associated with observations made on variables that required subjective assessment (Rosenthal 1969). Such assessments are common in some avian research, and an expectancy is usually inherent in hypothesis testing, an important tool of predictive science (Romesburg 1981). Researchers in some disciplines that are sensitive to the problem commonly employ techniques such as blind experiments, film records, and interobserver reliability checks to reduce or monitor the bias. Ornithologists, unfortunately, usually do not employ such techniques (Balph and Balph 1983). We probed the impact on avian research of this form of bias in two ways. First, we reviewed the results of some experiments designed to measure the bias in recording the activity of animals, and second, we applied the error found in these studies to some recent investigations to demonstrate how bias might affect the results.
D.F. Balph and H.C. Romesburg. 1986. The Possible Impact of Observer Bias on Some Avian Research. The Auk, 103:831-832.