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Abstract

This article illustrates a method to estimate the effects on the statistical power of a study that accompany changes in the reliability of the dependent variable. Examples are given where σ is available in the planning stage of a study (such as when standardized tests are to be used), as well as for situations in which the investigator must deal in standard deviation units, i.e., z-scores. When power is very high (e.g., above :95), it will continue to be very high (e.g., above .90) even if reliability is reduced considerably, such as by using a half-lengthened test. But if power falls in the moderate or low range, such increases or decreases of the dependent variable can have a large effect on the statistical power of the study.

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References

Brewer, J.K. On the power of statistical test. American Educational Research Journal, 1972,9, 391-401.

Cleary, T.A. , & Linn, R.L. Error of measurement and the power of a statistical test. British Journal of Mathematical and Statistical Psychology, 1969, 22, 49-55.

Cochran, W.G. Errors of measurement in statistics. Technometrics, 1968, 10, 637- 666.

Cochran, W.G. Some effects or errors of measurement on multiple correlations. Journal of the American Statistical Association, 1970,65, 22-34.

Cohen, J. Statistical power analysis and research results. American Educational Research Journal, 1973, 10, 225-229.

Glass, G.V. , & Stanley, J.C. Statistical methods in education and psychology. Englewood Cliffs, N.J.: Prentice-Hall, 1970 .

Hopkins, K.D. Preventing the number-one misinterpretation of behavioral research, or how to increase statistical power. Journal of Special Education , 1973, 7, 103-107.

Nicewander, W.A. , & Price, J.M. Dependent variable reliability and the power of significance test. Psychological Bulletin, 1978, 85, 405-409.

Sutcliff, J.P. Error of measurement and the sensitivity of a test of significance. Psychometrica, 1958, 23, 9-17.

10.

Winer, B.J. Statistical principles in experimental design (2nd ed.). New York: McGraw-Hill, 1971.

The Effect of the Reliability of the Dependent Variable On Power

Abstract

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