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The Analysis Of Partial Credit Scoring, Geoff Masters
The Analysis Of Partial Credit Scoring, Geoff Masters
Prof Geoff Masters AO
This article discusses a range of issues in the practical application of an item response theory (IRT) method for partial credit scoring. After a brief discussion of partial credit scoring as an alternative to right-wrong scoring in the measurment of educational achievement, an IRT model for partial credit analysis is developed and described. This model is presented as a straightforward and logical application of Rasch's dichotomous model to a sequence of ordered response alternatives. The distinctive nature of the item parameters in the model is described and these parameters are contrasted with two more familiar sets of parameters: Thurstone thresholds …
Item Discrimination: When More Is Worse, Geoff Masters
Item Discrimination: When More Is Worse, Geoff Masters
Prof Geoff Masters AO
High item discrimination can be a symptom of a special kind of measurement disturbance introduced by an item that gives persons of high ability a special advantage over and above their higher abilities. This type of disturbance, which can be interpreted as a form of item bias, can be encouraged by methods that routinely interpret highly discriminating items as the best items on a test and may be compounded by procedures that weight items by their discrimination. The type of measurement disturbance described and illustrated in this paper occurs when an item is sensitive to individual differences on a second, …