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Download full textHolland, Paul W.; Thayer, Dorothy T. – 1985
An alternative definition has been developed of the delta scale of item difficulty used at Educational Testing Service. The traditional delta scale uses an inverse normal transformation based on normal ogive models developed years ago. However, no use is made of this fact in typical uses of item deltas. It is simply one way to make the probability…
Descriptors: Difficulty Level, Error Patterns, Estimation (Mathematics), Item Analysis
