It is shown how the difference between the success rates in two treatment groups is related to the treatment-outcome correlation and the overall success rate. A new measure of effect size is proposed, which is easily calculated and readily interpretable in terms of the ratio of success rates in the treatment groups.
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References
1.
Cohen, J.Some statistical issues in psychological research. In B. B. Wolman (Ed.), Handbook of clinical psychology. New York: McGraw-Hill, 1965.
2.
Cohen, J.Statistical power analysis for the behavioral sciences (Rev. ed.). New York: Academic Press, 1977.
3.
Friedman, H.Magnitude of experimental effect and a table for its rapid estimation . Psychological Bulletin, 1968, 70, 245-251.
4.
Glass, G. V. , McGaw, B., and Smith, M. L.Meta-analysis in social research. Beverly Hills: Sage, 1981.
5.
Hays, W. L.Statistics. London: Holt, Rinehart and Winston, 1963.
6.
Rosenthal, R. and Rubin, D. B.A note on percent variance explained as a measure of the importance of effects. Journal of Applied Social Psychology, 1979, 9, 395-396.
7.
Rosenthal, R. and Rubin, D. B.A simple, general purpose display of magnitude of experimental effect. Journal of Educational Psychology, 1982, 74, 166-169.
