2 ms·

I would think that any standardized measure claiming to accurately measure beyond 2.5 sds would be a very noisy measure, almost pointlessly so

tokenadult 17y ago
any standardized measure claiming to accurately measure beyond 2.5 sds would be a very noisy measure, almost pointlessly so Yes. Even better than saying "measure" would be to say "estimate of rank order," but indeed it has been well known for a long time that IQ tests have their greatest error of estimation at the high end of the IQ scale. Lewis Terman, the developer of the first widely used school IQ test in the United States, the Stanford-Binet, noted that error of estimation in IQ scores increases as IQ scores are above the mean. "The reader should not lose sight of the fact that a test with even a high reliability yields scores which have an appreciable probable error. The probable error in terms of mental age is of course larger with older than with young children because of the increasing spread of mental age as we go from younger to older groups. For this reason it has been customary to express the P.E. [probable error] of a Binet score in terms of I.Q., since the spread of Binet I.Q.'s is fairly constant from age to age. However, when our correlation arrays [between Form L and Form M] were plotted for separate age groups they were all discovered to be distinctly fan-shaped. Figure 3 is typical of the arrays at every age level. http://learninfreedom.org/Terman%201937%20Figure%203.gif http://learninfreedom.org/Terman%201937%20Figure%203.gif "From Figure 3 it becomes clear that the probable error of an I.Q. score is not a constant amount, but a variable which increases as I.Q. increases. It has frequently been noted in the literature that gifted subjects show greater I.Q. fluctuation than do clinical cases with low I.Q.'s . . . . we now see that this trend is inherent in the I.Q. technique itself, and might have been predicted on logical grounds." (Terman & Merrill, 1937, p. 44) Terman, Lewis & Merrill, Maude (1937). Measuring Intelligence: A Guide to the Administration of the New Revised Stanford-Binet Tests of Intelligence. Boston: Houghton Mifflin.

tokenadult 17y ago

any standardized measure claiming to accurately measure beyond 2.5 sds would be a very noisy measure, almost pointlessly so Yes. Even better than saying "measure" would be to say "estimate of rank order," but indeed it has been well known for a long time that IQ tests have their greatest error of estimation at the high end of the IQ scale. Lewis Terman, the developer of the first widely used school IQ test in the United States, the Stanford-Binet, noted that error of estimation in IQ scores increases as IQ scores are above the mean. "The reader should not lose sight of the fact that a test with even a high reliability yields scores which have an appreciable probable error. The probable error in terms of mental age is of course larger with older than with young children because of the increasing spread of mental age as we go from younger to older groups. For this reason it has been customary to express the P.E. [probable error] of a Binet score in terms of I.Q., since the spread of Binet I.Q.'s is fairly constant from age to age. However, when our correlation arrays [between Form L and Form M] were plotted for separate age groups they were all discovered to be distinctly fan-shaped. Figure 3 is typical of the arrays at every age level. http://learninfreedom.org/Terman%201937%20Figure%203.gif http://learninfreedom.org/Terman%201937%20Figure%203.gif "From Figure 3 it becomes clear that the probable error of an I.Q. score is not a constant amount, but a variable which increases as I.Q. increases. It has frequently been noted in the literature that gifted subjects show greater I.Q. fluctuation than do clinical cases with low I.Q.'s . . . . we now see that this trend is inherent in the I.Q. technique itself, and might have been predicted on logical grounds." (Terman & Merrill, 1937, p. 44) Terman, Lewis & Merrill, Maude (1937). Measuring Intelligence: A Guide to the Administration of the New Revised Stanford-Binet Tests of Intelligence. Boston: Houghton Mifflin.