Browsing by Author "Formann, Anton K."

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    Measuring change by means of a hybrid variant of the linear logistic model with relaxed assumptions
    (1989) Formann, Anton K.; Spiel, Christiane
    The linear logistic model with relaxed assumptions (LLRA) was developed for measuring changes in qualitative data. It assumes item-specific person parameters and thus does not require homogeneous items to be presented to the persons at two points in time. The hybrid variant of this model maintains the multidimensionality of the person parameters, but it allows for different sets of items each of which is presented only once. In the model, a Rasch homogeneous item at2t with possibly differing difficulty corresponds to each item at t1. A short description of both models is followed by a first application of the hybrid LLRA to empirical data from a study on text comprehension. This example not only serves to demonstrate possible results when applying the LLRA, but is also used to outline the principle of hypothesis testing and model controls. Index terms: dichotomous data, linear logistic model, measuring change, Rasch model, text comprehension.
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    Some applications of logistic latent trait models with linear constraints on the parameters
    (1982) Fischer, Gerhard H.; Formann, Anton K.
    The linear logistic test model (LLTM), a Rasch model with linear constraints on the item parameters, is described. Three methods of parameter estimation are dealt with, giving special consideration to the conditional maximum likelihood approach, which provides a basis for the testing of structural hypotheses regarding item difficulty. Standard areas of application of the LLTM are surveyed, including many references to empirical studies in item analysis, item bias, and test construction; and a novel type of application to response-contingent dynamic processes is presented. Finally, the linear logistic model with relaxed assumptions (LLRA) for measuring change is introduced as a special case of an LLTM; it allows the characterization of individuals in a multidimensional latent space and the testing of hypotheses regarding effects of treatments.