Statistical power and Type II errors in social work research

In the use of statistical tests of hypotheses, the probability of correctly rejecting the null hypothesis is known as statistical power. A study designed with low statistical power is a study designed with a high probability of failure. The study discussed in this article examined the statistical power of articles published in Social Work Research and Abstracts from 1977 through 1984. The results indicated that almost halt the reported studies could not detect a medium effect size with adequate statistical power.