%0 Electronic Article %A Burns, Edward %I SAGE Publications %D 1982 %D 1982 %G English %@ 0022-4669 %@ 1538-4764 %~ Katalog UB TU-Chemnitz %T Bivariate Normal Distribution Estimates of The Prevalence of Reading Disabilities %V 16 %J The Journal of Special Education %V 16 %N 4 %P 431-437 %U http://dx.doi.org/10.1177/002246698201600406 %X The bivariate normal distribution can be used to determine the prevalence of reading disabilities when the primary variables are reading achievement and IQ and when the correlation between reading and IQ is known or can be estimated. In the case where the reading achievement z score cutoff is <– 1.0 (z scores less than– 1.0) and the IQz score cutoff is > -.7 (z scores greater than -.7), and the correlation between reading and IQ is .65, the proportion of reading-disability cases is .0576. This is in contrast to using only a reading z score cutoff of < −1.0, which would result in a proportion of .1587 based on the normal distribution. Using IQ to limit classification as reading disabled will decrease the proportion of reading-disability cases, depending on the z score cutoff points and the correlation between reading and IQ. As the correlation between reading and IQ increases, for any two cutoff points, the proportion of reading-disability cases decreases. The author discusses the advantages and disadvantages of using the bivariate normal distribution to estimate the prevalence of reading disabilities. %Z https://katalog.bibliothek.tu-chemnitz.de/Record/ai-49-aHR0cDovL2R4LmRvaS5vcmcvMTAuMTE3Ny8wMDIyNDY2OTgyMDE2MDA0MDY %U https://katalog.bibliothek.tu-chemnitz.de/Record/ai-49-aHR0cDovL2R4LmRvaS5vcmcvMTAuMTE3Ny8wMDIyNDY2OTgyMDE2MDA0MDY