Showing papers by "Tilburg University published in 1982"

Cross-Cultural Generalization and Universality

Abstract: Different meanings of the concept universality are distinguished and ordered according to the degree to which they are open to empirical control. Universality and specificity are considered as relative rather than absolute concepts. A relationship between the analysis of universality and the analysis of comparability or psychometric equivalence of data is established. An integrated approach to the analysis of universality and equivalence within the context of Generalizability Theory is outlined and illustrated with an example.

Changes of Achilles Tendon Reflex Amplitudes During a Fixed Foreperiod of Four Seconds

Abstract: Preparation for a voluntary foot or finger response was studied by evoking Achilles tendon (T) reflexes. Reflexes were evoked simultaneously in both legs at 13 points between 100 and 4300 msec after the warning signal. With this paradigm, the time course of changes in reflex amplitudes related to preparatory processes could be measured simultaneously in the leg involved in the response and in the uninvolved leg. Immediately following the warning stimulus, the reflex amplitudes increased in both involved and non-involved muscles, presumably reflecting a general non-specific arousal. During the second half of the foreperiod, reflex amplitudes in non-involved muscles remained elevated, perhaps reflecting a general activation of the motor system, but returned to baseline in the involved muscles. It is hypothesized that the consistently smaller reflex amplitudes in the involved leg during the entire ISI reflect a presynaptic inhibition of the la afferents to the motoneurons involved in the response. Following the response stimulus, reflex amplitudes increased in both involved and non-involved muscles, although in the former at an earlier point and to a greater extent. It is suggested that this increase following the response stimulus is a manifestation of the transition from motor preparation to response execution.

Habituation of the human blink reflex: The effect of stimulus frequency and the state of arousal

Abstract: Electrical stimulation of the supraorbital branch of the human facial nerve resulted in an oligosynaptic ipsilateral reflex (R1) and a polysynaptic bilateral late reflex (R2) of the orbicularis oculi muscle. Former studies had already reported different reaction patterns of R1 and R2 during mental tasks as well as during low-frequency stimulation. The present study was concerned with the possible difference in habituation of R1 and R2 under conditions with and without a mental task. The habituation paradigm was as follows: Ten control stimuli were presented at 1-min intervals. Identical stimuli were then given during a 30-min session at one of the following frequencies: 1/3.75 sec, 1/7.5 sec, 1/15 sec, 1/30 sec, and 1/60 sec, during which time subjects either had a continuous rest or performed a mental task. At the end of this session, the stimulation frequency changed to 1/3.75 sec. R1 increased during a mental task, whereas R2 was reduced. It was further concluded that R1 underwent more sensitization influences, as R2 showed more habituation, and that this divergence was due to differences in central neural pathways.

Statistical aspects of simulation: an updated survey*

Abstract: Practical statistical techniques for the design and analysis of simulation experiments are presented. These techniques are relevant in both discrete and continuous, deterministic and stochastic simulation. To generalize and interpret the simulation output the analyst can use regression analysis. This analysis allows for interactions among factors. Actually the regression model provides either a first-order or a second-order approximation to the complicated simulation model. To decide which system variants (parameter combinations) should be simulated, the analyst may apply experimental design theory. This theory makes the exploration of the simulated system much more efficient and more thorough. In the preliminary phase of the simulation experimentation special screening designs can be used to investigate hundreds of factors in relatively few runs. In stochastic simulation additional problems arise. There are several approaches for determining how to initialize a simulation run and how long to continue that run. These approaches result in a confidence interval for the estimated response. Both steady-state and transient behavior are examined. Special variance reduction techniques are briefly discussed; the use of common random numbers (identical seeds) is discussed in more detail.

Distribution, taxation and employment in an open economy

Abstract: If taxes on labour income are passed on in wages the balanced budget multiplier may be negative. The present paper analyses this problem from a theoretical point of view applying a linearized version of a model for the small open economy. The model is dynamic, because account is taken of capital accumulation. Short-run and long-run solutions are expressed in terms of fiscal policy variables, a wage push variable, the price level abroad and world demand. Numerical examples are supplemented to illustrate the analytical results.

Concrete Analogies as Aids in Learning From Text

Abstract: Various theorists have proposed different reasons for the usefulness of concrete analogies in written texts. Some stress a concretizing function, others a structurizing function, and still others suggest that analogies induce a more active processing of the text. The main question which we tried to answer in a series of six experiments were: (a) Does the addition of concrete analogies lead to higher performances and longer reading-times in subjects of different ages? (b) What are the effects under restricted time conditions? (c) Why are concrete analogies effective? (d) Are there aptitude-treatment interactions? In general, the results showed that subjects, when confronted with analogies, not only studied longer, but learned more and different things. However, if the study time was limited, these effects disappeared. Furthermore some aptitude-treatment interactions were found, especially in the case of the visualizer-verbalizer dimension. All three of the above mentioned functions of analogies were supported by the data.

Self-Regulated Versus Teacher-Provided Sequencing of Information in Learning From Text

Abstract: Three experiments are discussed in which differential effects of self-regulated and teacher-provided subject matter sequences were examined. In all experiments secondary school children took an introductory course in physics, which was presented to them in written format. In general, data revealed that subjects performed better on achievement tests (post- and retention tests) under self-regulated conditions, than under teacher-provided ones. Furthermore, subjects under self-regulated conditions were better able to construct an internal representation of the subject matter. In addition, several disordinal aptitude-treatment interactions were detected for inductive and deductive reasoning ability, field independence and analogical reasoning ability. Learners scoring high on these characteristics had an advantage under conditions of self-sequencing and were held back under teacher-provided sequences. The opposite, however, was true for learners judged as low on these aptitudes.

The specification problem in regression analysis

Abstract: Summary This paper reviews a number of statistical and economic-theoretical arguments in the specification of a regression equation. Special attention is paid to the specification choice of levels versus first differences and levels versus logarithms. From the literature some ad hoc arguments concerning these choices have been summed up. Attention is also paid to the usefulness of Box-Jenkins time series analysis and the specification analysis of Hendry, Mizon et al. in choosing between a specification in levels and first differences. The theoretical plausibility of regression results serves as a limiting condition. Examples are therefore given in which theory prescribes the form of the equation. Finally a review is presented of the specification in a number of models.

Stability of a discrete-time, macroeconomic disequilibrium model

Abstract: We investigate the stability of a macroeconomic monetary discrete-time model with a constraint on the market for bank-credit. A theorem is proved on asymptotic stability of a piecewise linear discrete-time system in R 2.

EDUSERVICE--A Computer Assisted Evaluation System. Some Design Considerations.

Abstract: Computer Managed Learning (CML) is often regarded as only an interim approach to the adoption of Computer Assisted Learning (CAL). In this paper CML is discussed both as part of an innovative strategy and as a means to support the classroom teacher in its own right. It is argued that. from a centralised point of view, introduction of the computer in support of education can best be started from the bottom, i.e. in rather simple administrative and managerial tasks. One such introductory development is described in detail.