Biomedical subjects

F Tuerlinckx

Publications and source records attributed to F Tuerlinckx.

3 recordsLinked to original sources

PubMed2001

The effect of ignoring item interactions on the estimated discrimination parameters in item response theory.

Most item response theory models assume conditional independence, and it is known that interactions between items affect the estimated item discrimination. In this article, this effect is further investigated from a theoretical perspective and by means of simulation studies. To this end, a parametric model for item interactions is introduced. Next, it is shown that ignoring a positive interaction results in an overestimation of the discrimination parameter in the two-parameter logistic model (2PLM), whereas ignoring a negative interaction leads to an underestimation of the parameter. Furthermore, it is demonstrated that in some cases the item characteristic curves of the 2PLM and of an item involved in an interaction are quite similar, indicating that the 2PLM can provide a good fit to data with interactions.

Humans↗

PubMed2001

Task perception as a mediating variable: a contribution to the validation of instructional knowledge.

BACKGROUND: From the perspective of the cognitive mediational paradigm, we focus in this study on students' conceptions of the relationship between instructional interventions and learning: 'instructional knowledge'. AIMS: Task perception has been investigated as a procedural manifestation of instructional knowledge. Four research questions directed the study: (1) how do students perceive a task; (2) by which structure can the relations between categories of task perception be represented; (3) do students differ in their task perception; and (4) is there a significant relationship between students' task perception and the learning activities they plan and/or execute. SAMPLE: The sample consisted of 149 university freshmen in educational sciences. METHODS: Students were confronted with a concrete task in a natural setting. Correlations were searched for by phi coefficient. Hierarchical classes analysis was used to search for hierarchical relations and inter-individual differences. Goodman-Kruskal lambda was calculated to estimate the association between students' task perception and the learning activities they planned and executed. The questionnaire and the design of the coding systems were first tried out in a pilot study. RESULTS: Students' task perception can be described in 11 categories. Correlations between those categories were low, but a simple hierarchical structure was discovered. Students can be distinguished according to their task perception into eight groups. Finally, the results indicate a statistically significant association between students' task perception and the learning activities they plan and execute. CONCLUSIONS: The study provides additional evidence to involve 'instructional knowledge' and students' task perception as part of it, as mediating variables in future research.

Adult↗

PubMed2001

A comparison of four methods for simulating the diffusion process.

Four methods for the simulation of the Wiener process with constant drift and variance are described. These four methods are (1) approximating the diffusion process by a random walk with very small time steps; (2) drawing directly from the joint density of responses and reaction time by means of a (possibly) repeated application of a rejection algorithm; (3) using a discrete approximation to the stochastic differential equation describing the diffusion process; and (4) a probability integral transform method approximating the inverse of the cumulative distribution function of the diffusion process. The four methods for simulating response probabilities and response times are compared on two criteria: simulation speed and accuracy of the simulation. It is concluded that the rejection-based and probability integral transform method perform best on both criteria, and that the stochastic differential approximation is worst. An important drawback of the rejection method is that it is applicable only to the Wiener process, whereas the probability integral transform method is more general.

Algorithms↗