The Regression Discrepancy Model (RDM) was originally offered as a method to increase accuracy in assessing severe discrepancy by accounting for regression effects and measurement error. However, demonstration that the RDM realizes its goal of accurate, nonbiased assessment of IQ-achievement discrepancies has not been provided. The RDM's mathematical equations are examined, particularly the initial equation evaluating significant difference between IQ and achievement scores. Results from the initial equation are shown to be related to IQ levels and to bias the detection of severe discrepancy at lower IQ levels. Methods to minimize or remove this bias are proposed.
Get full access to this article
View all access options for this article.
References
1.
Algozzine, B., & Ysseldyk, J.E. (1983). Learning disabilities as a subset of school failure: The oversophistication of a concept. Exceptional Children, 50, 242‐246.
2.
Algozzine, B., & Ysseldyke, J.E. (1987). Questioning discrepancies: Retaking the first step 20 years later. Learning Disability Quarterly, 10, 301‐312.
3.
Algozzine, B., Ysseldyke, J.E., & Shinn, M. (1982). Identifying children with learning disabilities: When is a discrepancy severe. Journal of School Psychology, 20, 299‐305.
4.
Bennett, D., & Clarizio, H.F. (1988). A comparison of methods for calculating severe discrepancy. Journal of School Psychology, 26, 359‐369.
5.
Boodoo, G.M. (1984). A multivariate perspective for aptitude-achievement discrepancy in learning disability assessment. The Journal of Special Education, 18, 39‐44.
6.
Braden, J.P. (1987). A comparison of regression and standard score discrepancy methods for learning disabilities identification: Effects on racial representation. Journal of School Psychology, 25, 23‐29.
7.
Braden, J.P., & Algina, J. (1989). A method for determining the probability of special education eligibility. Journal of School Psychology, 27, 5‐13.
8.
Braden, J.P., & Weiss, L. (1988). Effects of simple difference versus regression discrepancy methods: An empirical study. Journal of School Psychology, 26, 133‐142.
9.
Clarizio, H.F., & Phillips, S.E. (1989). Defining severe discrepancy in the diagnosis of learning disabilities: A comparison of methods. Journal of School Psychology, 27, 383‐391.
10.
Cone, T.F. (1986, March). The LD parable: A very unfortunate assumption. NASP Communique, 14, 8‐9.
11.
Hammill, D.D. (1990). On defining learning disabilities: An emerging consensus. Journal of Learning Disabilities, 23, 74‐84.
Macmann, G.M., Barnett, D.W., Lombard, T.J., Belton-Kocher, E., & Sharpe, M.N. (1989). On the actuarial classification of children: Fundamental studies of classification agreement. The Journal of Special Education, 23, 127‐149.
14.
McDermott, P.A., & Watkins, M.W. (1985). Microcomputer systems manual for McDermott multidimensional assessment of children. San Antonio, TX: Psychological Corp.
15.
McLeskey, J., Waldron, N.L., & Wornhoff, S.A. (1990). Factors influencing the identification of black and white students with learning disabilities. Journal of Learning Disabilities, 23, 362‐366.
16.
Payne, R.W., & Jones, H.G. (1957). Statistics for the investigation of individual cases. Journal of Clinical Psychology, 13, 115‐121.
17.
Reynolds, C.R. (1981). The fallacy of "two years below grade level for age" as a diagnostic criterion for reading disorders. Journal of School Psychology, 19, 350‐357.
18.
Reynolds, C.R. (1984). Critical issues in learning disabilities. The Journal of Special Education, 18, 451‐476.
19.
Reynolds, C.R. (1985). Toward objective diagnosis of learning disabilities. Special Services in the Schools, 2, 161‐176.
20.
Reynolds, C.R. (1990). Conceptual and technical problems in learning disability diagnosis. In C.R. Reynolds & R.A. Kamphaus (Eds.), Handbook of psychological and educational assessment of children: Intelligence and achievement (pp. 571–592). New York: Guilford.
21.
Reynolds, C.R., & Stanton, J. (1990). The discrepancy determinator-Revise. [Computer program]. Bensalem, PA: Train.
22.
Reynolds, C.R., Berk, R.A., Boodoo, G.M., Cox, J., Gutkin, T.B., Mann, L., Page, E.B., & Willson, V.L. (1983). Critical issues in learning disabilities. Washington, DC: U.S. Department of Education, Special Education Work Group on Measurement Issues in the Assessment of Learning Disabilities.
23.
Salvia, J., & Ysseldyke, J.E. (1987). Assessment in special and remedial educatio. (4th ed.). Boston: Houghton Mifflin.
24.
Slate, J.R., & Hunnicutt, L.C. (1988). Examiner errors on the Wechsler scales. Journal of Psychoeducational Assessment, 6, 280‐288.
25.
Shepard, L. (1980). An evaluation of the regression discrepancy method for identifying children with learning disabilities. The Journal of Special Education, 14, 79‐91.
26.
Thorndike, R.L. (1963). The concepts of over-and underachievement. New York: Columbia University Teachers College.
27.
Willson, V.L., & Reynolds, C.R. (1984). Another look at evaluating aptitude-achievement discrepancies in the diagnosis of learning disabilities. The Journal of Special Education, 18, 27‐37.
28.
Wilson, L.R., & Cone, T. (1984). The regression equation method of determining academic discrepancy. Journal of School Psychology, 22, 95‐110.
