Abstract
A “strong” mathematical model for the relation between observed scores and true scores is developed. This model can be used
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1.
To estimate the frequency distribution of observed scores that will result when a given test is lengthened.
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To equate true scores on two tests by the equipercentile method.
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To estimate the frequencies in the scatterplot between two parallel (nonparallel) tests of the same psychological trait, using only the information in a (the) marginal distribution(s).
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4.
To estimate the frequency distribution of a test for a group that has taken only a short form of the test (this is useful for obtaining norms).
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5.
To estimate the effects of selecting individuals on a fallible measure.
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6.
To effect matching of groups with respect to true score when only a fallible measure is available.
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7.
To investigate whether two tests really measure the same psychological function when they have a nonlinear relationship.
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8.
To describe and evaluate the properties of a specific test considered as a measuring instrument.
The model has been tested empirically, using it to estimate bivariate distributions from univariate distributions, with good results, as checked by chi-square tests.
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References
Appell, P. and Kampé de Fériet, J. Fonctions hypergeometriques et hyperspheriques. Polynomes d' Hermite. Gauthier-Villars, 1926.
Buckingham, R. A.Numerical methods. London: Pitman, 1957.
Bückner, H. F. Numerical methods for integral equations. In J. Todd (Ed.),A survey of numerical analysis. New York: McGraw-Hill, 1962.
Cochran, W. G. Some methods for strengthening the common x2 tests.Biometrics, 1954,10, 417–451.
Eisenberg, H. B., Geoghagen, R. R. M., and Walsh, J. E. A general probability model for binomial events with application to surgical mortality.Biometrics, 1963,19, 152–157.
Elderton, Sir W. P.Frequency curves and correlation. (3rd ed.). Cambridge, England: Cambridge Univ. Press, 1938.
Erdélyi, A., Magnus, W., Oberhettinger, F., and Tricomi, F. G.Higher transcendental functions. Vol. 1. New York: McGraw-Hill, 1953.
Fox, L. and Goodwin, E. T. The numerical solution of non-singular linear equations.Phil. Trans. roy. Soc. London (Series A), 1952–53,245, 501–535.
Gulliksen, H. O.Theory of mental tests. New York: Wiley, 1950.
Hirschman, I. I. and Widder, D. V.The convolution transform. Princeton: Princeton Univ. Press, 1955.
Jeffries, J. and Orrall, F. The numerical solution of Fredholm integral equations of the first kind. (Unclassified report reproduced by the Armed Services Technical Information Agency.) Arlington, Va.: Arlington Hall Station. November 1960. AD 250–862.
Kantorovich, L. W. and Krylov, V. I.Approximate methods of higher analysis. New York: Interscience, 1958.
Keats, J. A. and Lord, F. M. A theoretical distribution for mental test scores.Psychometrika, 1962,27, 59–72.
Kendall, M. G. and Stuart, A.The advanced theory of statistics. New York: Hafner, 1958.
Kunz, K. S.Numerical analysis. New York: McGraw-Hill, 1957.
Lord, F. M. A theory of test scores.Psychometric Monogr., No. 7. Richmond, Va.: William Byrd Press, 1952.
Lord, F. M. An approach to mental test theory.Psychometrika, 1959,24, 283–302.
Lord, F. M. Use of true-score theory to predict moments of univariate and bivariate observed-score distributions.Psychometrika, 1960,25, 325–342.
Lord, F. M. Estimating true measurements from fallible measurements (Binomial Case)—expansion in a series of beta distributions. Res. Bull. 62-23. Princeton, N. J.: Educ. Test. Serv., 1962.
Lord, F. M. True-score theory—The four parameter beta model with binomial errors. Res. Bull. 64-6. Princeton, N. J.: Educ. Test. Serv., 1964.
Medgyessy, P.Decomposition of superpositions of distribution functions. Budapest: Publishing House of the Hungarian Academy of Sciences, 1961.
Phillips, D. L. A technique for the numerical solution of certain integral equations of the first kind.J. Ass. comput. Machinery, 1962,9, 84–97.
Pollard, H. Distribution functions containing a Gaussian factor.Proc. Amer. math. Soc., 1953,4, 578–582.
Rasch, G.Probabilistic models for some intelligence and attainment tests. Copenhagen, Denmark: Nielsen and Lydiche (M. Simmelkiaer), 1960.
Teicher, H. On the mixture of distributions.Ann. math. Statist., 1960,31, 55–73.
Tricomi, F. G.Integral equations. New York: Interscience, 1957.
Trumpler, R. J. and Weaver, H. F.Statistical astronomy. Berkeley: Univ. California Press, 1953.
Tucker, L. R. A note on the estimation of test reliability by the Kuder-Richardson formula (20).Psychometrika, 1949,14, 117–120.
Twomey, S. On the numerical solution of Fredholm integral equations of the first kind by the inversion of the linear system produced by quadrature.J. Ass. comput. Machinery, 1963,10, 97–101.
Walsh, J. E. Corrections to two papers concerned with binomial events.Sankhyā, Ser. A., 1963,25, 427.
Walther, A. and Dejon, B. General report on the numerical treatment of integral and integro-differential equations. InSymposium on the Numerical Treatment of Ordinary Differential Equations, Integral and Integro-Differential Equations—Proceedings of the Rowe Symposium (20–24 September 1960). Basel/Stuttgart: Birkhauser Verlag, 1960. Pp. 645–671.
Young, A. Approximate product-integration.Proc. roy. Soc., A, 1954,224, 552–561.
Young, A. The application of product-integration to the numerical solution of integral equations.Proc. roy. Soc., A, 1954,224, 561–573.
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This work was supported in part by contract Nonr-2752(00) between the Office of Naval Research and Educational Testing Service. Reproduction in whole or in part for any purpose of the United States Government is permitted. Many of the extensive computations were done on Princeton University computer facilities, supported in part by National Science Foundation Grant NSF-GP579. The last portion of the work was carried out while the writer was Brittingham Visiting Professor at the University of Wisconsin. The writer is indebted to Diana Lees, who wrote many of the computer programs, checked most of the mathematical derivations, and gave other invaluable assistance throughout the project.
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Lord, F.M. A strong true-score theory, with applications. Psychometrika 30, 239–270 (1965). https://doi.org/10.1007/BF02289490
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DOI: https://doi.org/10.1007/BF02289490