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Browsing by Author "Haertel, Edward"

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    Applicability of the Rasch model with varying item discriminations
    (1977) Dinero, Thomas E.; Haertel, Edward
    Among the varieties of logistic models, those attributed to Birnbaum (involving the parameters of item discrimination, item difficulty, and person ability) and Rasch (involving only item difficulty and person ability) have received attention. The present research simulated the responses of 75 subjects responding to 30 items under the Birnbaum model and then attempted a fit to the data using the Rasch model. When item discriminations varied from a variance of .05 to .25 within distributions of different form (uniform, normal, and positively skewed), the poorest overall fit appeared within the uniform distribution. For each distribution there was only a slight increase in the lack of fit as the variances increased.
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    An application of latent class models to assessment data
    (1984) Haertel, Edward
    Responses of 17-year-olds to selected 1977-78 National Assessment of Educational Progress (NAEP) mathematics exercises were analyzed, using latent class models. A single model was fitted to data from five independent samples of examinees, each of which responded to a different set of six algebra or prealgebra exercises. Four categories of items were found, defining five levels of content mastery, ranging from examinees unable to solve any of the exercises (43%) through those able to solve all the exercises (19%). The methods demonstrated are broadly applicable to assessment data, including matrix-sampled data, and provide an aggregate description of examinee abilities independent of the specific characteristics of individual exercises administered.