Browsing by Author "Wilson, Mark"

Now showing 1 - 8 of 8
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    Complex composites: Issues that arise in combining different modes of assessment
    (1995) Wilson, Mark; Wang, Wen-chung
    Data from the California Learning Assessment System are used to examine certain characteristics of tests designed as the composites of items of different modes. The characteristics include rater severity, test information, and definition of the latent variable. Three different assessment modes-multiple-choice, open-ended, and investigation items (the latter two are referred to as performance- based modes)-were combined in a test across three different test forms. Rater severity was investigated by incorporating a rater parameter for each rater in an item response model that then was used to analyze the data. Some rater severities were found to be quite extreme, and the impact of this variation in rater severities on both total scores and trait level estimates was examined. Within-rater variation in rater severity also was examined and was found to have significant variation. The information contribution of the three modes was compared. Performance-based items provided more information than multiple-choice items and also provided greatest precision for higher levels of the latent variable. A projection-like method was applied to investigate the effects of assessment mode on the definition of the latent variable. The multiple-choice items added information to the performance-based variable. The results of the analysis also showed that the projection-like method did not practically differ from the results when the latent trait was defined jointly by both the multiple-choice and the performance-based items. Index terms: equating, linking, multiple assessment modes, polytomous item response models, rater effects.
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    Detecting and interpreting local item dependence using a family of Rasch models
    (1988) Wilson, Mark
    This paper describes a method for detecting and interpreting disturbances of the local independence assumption among items that share common stimulus material or other substantive features. Dichotomous and polytomous Rasch models are used in an example to analyze Structure of the Learning Outcome (SOLO) superitems and examine the results for local independence problems. The results indicate that some disturbances were present among particular subsets of the items. Index terms: local independence, partial credit model, one-parameter logistic model, Rasch model, rating scale model.
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    The Effect of Two Cooling Protocols on Quality of Liquid Boar Semen
    (1998-09-18) Lorton, Steven; Ga1l, Thomas; Wilson, Mark
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    Impact of season on reproduction
    (2006-09-23) Wilson, Mark
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    Lameness hurts sow reproduction
    (2009-09-19) Wilson, Mark; Ward, Terry; Rapp, Christof
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    The ordered partition model: An extension of the partial credit model
    (1992) Wilson, Mark
    An item response model, called the ordered partition model, is designed for a measurement context in which the categories of response to an item cannot be completely ordered. For example, two different solution strategies may lead to an equivalent degree of success because both strategies may result in the same score, but an examiner may want to maintain the distinction between the strategies. Thus, the data would not be nominal nor completely ordered, so may not be suitable for other polytomous item response models such as the partial credit or the graded response models. The ordered partition model is described as an extension of the partial credit model, its relationship to other models is discussed, and two examples are presented. Index terms: ordered partition model, partial credit model, partial order model, polytomous IRT model, Rasch model.
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    Quantification of Bacteria in Fractionat~d Boar Ejaculates
    (1998-09-18) Gall, Tom; Wilson, Mark; Althouse, G. C.