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Regression Fallacies in the Matched Groups Experiment

Published online by Cambridge University Press:  01 January 2025

Robert L. Thorndike*
Affiliation:
Teachers College, Columbia University

Abstract

This paper is concerned particularly with certain regression effects which appear whenever matched groups are drawn from populations which differ with regard to the characteristics being studied. It is shown that regression will produce systematic differences between specifically matched. The size and direction of these differences depends upon the differences between the parent populations both in the matching and in the experimental variables and upon the correlation between the matching and experimental variables. Formulas are presented for estimating the expected regression effect. Several alternative procedures are suggested for avoiding the erroneous conclusions which the regression effect is likely to suggest.

Type
Original Paper
Copyright
Copyright © 1942 The Psychometric Society

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References

* McNemar, Quim. Sampling in psychological research. Psychol. Bull., 1940, 37, 331-365.

* Crissey, O. L. Mental development as related to institutional and educational residence. University of Iowa Studies in Child Welfare, 1937, 18, No. 1, p. 81

* For a discussion of analysis of covariance, see Snedecor, G. W. Statistical Methods. Ames, Iowa: Collegiate Press, 1938

For Lindquist, E. F. Statistical Analysis in Educational Research. New York: Houghton Mifflin, 1940.

* Johnson, P. O. and Neyman, J. Tests of Certain Linear Hypotheses and Their Application to some Educational Problems. Statistical Research Memoirs, 1936. 1

* Peters, C. C. A Method of Matching Groups for Experiment With No Loss of Population. J. educ. Research, 1941, 34, 606-612.