Differential diagnosis of ability in school children / by David Segel.

  • Segel, David.
Date:
1934
Catalogue details

Licence: In copyright

Credit: Differential diagnosis of ability in school children / by David Segel. Source: Wellcome Collection.

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    SECOND METHOD OF MAKING A DIFFERENTIAL DIAGNOSIS This method of discovering idiosyncrasies was developed by Kelley.** This method of making a differential diagnosis allows for the differences in variables of a group in the two or more measures involved by assuming standard deviations equiv- alent, whereas the first method does not do this. It involves the use of standard scores. Take the difference between any two test scores in different subjects, such as X; — Xo. These differences cannot be interpreted directly. They must first be expressed as deviations from the grade means divided by the standard deviation. This makes standard scores — —M expressed as follow: Z; = aioe LZ, = ee 1 2 Their standard deviations are then equal tol. There- fore, in standard scores the difference between X, Ay eo As el and X2 will be eas minus SSS or Z; — Zo. 1 2 33 Kelley, T. L. A new method for determining the signifi- cance of differences in intelligence and achievement scores. Journal of Educational Psychology, Vol. XIV, No. 6, Septem- ber, 1923, pp. 321-33. *It should be noted that the calculation of differences . between standard scores, i.e. such as ee — eee is & 1 2 different process than finding equivalent scores from the equa- : tion X,; = M, + 2k: — M.) even though they are both