A REASSESSMENT OF STATISTICAL POWER ANALYSIS IN HUMAN COMMUNICATION RESEARCH

Authors


John P. Garrison (Ph.D., University of Nebraska-Lincoln, 1978) is assistant professor of speech communication at Auburn University, Auburn, Alabama 36830. Garrison is also president of Learning Research Associates, Inc., Lincoln, Nebraska 68516. Peter A. Andersen (Ph.D., Florida State University, 1975) is assistant professor of speech communication at West Virginia University, Morgantown, West Virginia 26506. This study accepted for publication February 12, 1979.

Abstract

This study conducted a statistical power analysis of 64 articles appearing in the first four volumes of Human Communication Research, 1974–1978. Each article was examined, using Cohen's revised handbook, assuming nondirectional null hypotheses and an alpha level of .05. Statistical power, the probability of rejecting a false null hypothesis, was calculated for small, medium, and large experimental effect sizes and averaged by article and volume. Results indicated that the average probability of beta errors appears to have decreased over time, providing a greater chance of rejecting false null hypotheses, but this also raised several power-related issues relevant to communication research in general.

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