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Search Results: 1 - 10 of 152358 matches for " JOACHIM H?USLER "
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Adaptive success control in computerized adaptive testing
Psychology Science , 2006,
Abstract: In computerized adaptive testing (CAT) procedures within the framework of probabilistic test theory the difficulty of an item is adjusted to the ability of the respondent, with the aim of maximizing the amount of information generated per item, thereby also increasing test economy and test reasonableness.However, earlier research indicates that respondents might feel over-challenged by a constant success probability of p=0.5 and therefore cannot come to a sufficiently high answer certainty within a reasonable timeframe. Consequently response time per item increases, which – depending on the test material – can outweigh the benefit of administering optimally informative items. Instead of a benefit, the result of using CAT procedures could be a loss of test economy.Based on this problem, an adaptive success control algorithm was designed and tested, adapting the success probability to the working style of the respondent. Persons who need higher answer certainty in order to come to a decision are detected and receive a higher success probability, in order to minimize the test duration (not the number of items as in classical CAT). The method is validated on the re-analysis of data from the Adaptive Matrices Test (AMT, Hornke, Etzel & Rettig, 1999) and by the comparison between an AMT version using classical CAT and an experimental version using Adaptive Success Control.The results are discussed in the light of psychometric and psychological aspects of test quality.
The effect of success probability on test economy and self-confidence in computerized adaptive tests
Psychology Science Quarterly , 2008,
Abstract: Recent research on the psychological effects of different design decisions in computerized adaptive tests indicates that the maximum-information item selection rule fails to optimize respondents’ test-taking motivation. While several recent studies have investigated psychological reactions to computerized adaptive tests using a consistently higher base success rate, little research has so far been conducted on the psychometric (primarily test reliability and bias) and psychological effects (e.g. test-taking motivation, self-confidence) of using mixtures of highly informative (p = .50) and easier items (p = .80) in the item selection process. The present paper thus compares these modifications to item selection with a classical maximum-information algorithm. In a simulation study the effect of the different item selection algorithms on measurement precision and bias in the person parameter estimates is evaluated. To do so, the item pool of the Lexical Knowledge Test, measuring crystallized intelligence and self-confidence, is used. The study indicated that modifications using base success probabilities over p = .70 lead to reduced measurement accuracy and - more seriously - a bias in the person parameter estimates for higher ability respondents. However, this was not the case for the motivator item algorithm, occasionally administering easier items as well. The second study (n = 191) thus compared the unmodified maximum-information algorithm with two motivator item algorithms, which differed with regard to the percentage of motivator items presented. The results indicate that respondents yield higher self-confidence estimates under the motivator item conditions. Furthermore, the three conditions did not differ from each other with regard to the total test duration. It can be concluded that a small number of easier motivator items is sufficient to preserve test-taking motivation throughout the test without a loss of test economy.
Optimizing technical precision of measurement in computerized psychological assessment on Windows platforms
Psychology Science , 2007,
Abstract: Reaction times and response latencies are required to measure a variety of ability and personality traits. If reaction times are used to measure rather elementary cognitive tasks, the inter-individual variance in the measured reaction times are usually small in the sense that the central 50 percent of a norm population range within less than 100ms. Technical measurement errors therefore have the potential to seriously affect the validity of diagnostic judgments based on such measures. Thus the target of this paper is to investigate the magnitude of possible errors of measurement due to technical reasons and to suggest ways to prevent or at least consider those in the diagnostic process.In Study I a highly precise 'artificial respondent' was applied to simulate reactions corresponding to a given percentile rank on 3 different tests (DG-Lokation CORPORAL, Alertness TAP-M, RT/S9 Vienna Test System) on 11 different computer systems. The result output of the tests was compared to the reaction times, actually provided by the artificial respondent. Results show, that there are detectable errors of measurement - depending on the hardware and software specifications of the computer system used. In the test DG-Lokation these bias caused an offset in the tests main variable of up to 20 percentile ranks.In Study II a self-calibration unit which is part of the Vienna Test System (Version 6.40) was investigated, using the same experimental setup. After calibration, the bias detected can be reduced to the magnitude of about 1 percentile rank on all computer systems tested.It thus can be concluded, that time critical computer based tests typically bear the risk of technical errors of measurement. Depending on how the test is programmed, the errors arising on some computer configurations can cause even severe changes in diagnostic judgment formation. In contrast, self-calibration proved to be an effective tool to permitting the user not only to control but also to ensure the precision of measurement, independent of the properties of the computer system he is administering his test on.
Assessing behavior in standardized settings: The role of objective personality tests
René T. Proyer,Joachim Husler
International Journal of Clinical and Health Psychology , 2007,
Abstract: En este estudio teórico los tests objetivos de personalidad son mostrados como una posible forma de evaluar el comportamiento en situaciones concretas. Se describe una nueva generación de tests objetivos de personalidad, vinculados al uso de computadoras. Una de las principales características de estos tests es que no presentan validez aparente y son, por consiguiente, menos susceptibles de falseamiento u otras distorsiones de respuesta que habitualmente se encuentran en la evaluación subjetiva de personalidad mediante cuestionarios. Se examinan los desarrollos recientes en el área de tests de personalidad objetivos. El Hyperkinetic Syndrome Assessment Method (HKSD) es descrito como ejemplo de la nueva generación de tests objetivos de personalidad. La justificación razonada de la construcción, propiedades psicométricas y resultados sobre su validez son expuestos. Los resultados de estudios con muestras clínicas y no clínicas sostienen la utilidad del HKSD en la práctica. Los tests objetivos de personalidad se discuten como alternativas en el campo de evaluación psicológica, como instrumentos válidos y económicos para la evaluación del comportamiento.
Gasteditorial: Pr nataler Ultraschall und der "dritte Bildungsweg"
Husler M
Speculum - Zeitschrift für Gyn?kologie und Geburtshilfe , 2011,
Ultraschall in der Schwangerschaft - die Qualit tsfrage
Husler M
Speculum - Zeitschrift für Gyn?kologie und Geburtshilfe , 2006,
Gasteditorial - La parole à l'invité
Husler M
Speculum - Zeitschrift für Gyn?kologie und Geburtshilfe , 2011,
Influence of spin on the persistent current of strongly interacting electrons
Wolfgang Husler
Physics , 1996, DOI: 10.1016/0921-4526(96)00228-1
Abstract: The lowest eigenenergies of few, strongly interacting electrons in a one--dimensional ring are studied in the presence of an impurity barrier. The persistent current $\:I\:$, periodic in an Aharonov--Bohm flux penetrating the ring, is strongly influenced by the electron spin. The impurity does not remove discontinuities in $\:I\:$ at zero temperature. The total electron spin of the ground state oscillates with the flux. Strong electron--electron interaction enhances $\:I\:$, albeit not up to the value of the clean ring which itself is smaller than $\:I\:$ for free electrons. $\:I\:$ disappears on a temperature scale that depends exponentially on the electron density. In the limit of very strong interaction the response to small fluxes is diamagnetic.
Dephasing in Rashba spin precession along mutlichannel quantum wires and nanotubes
Wolfgang Husler
Physics , 2004, DOI: 10.1103/PhysRevB.70.115313
Abstract: Coherent Rashba spin precession along interacting multi-mode quantum channels is investigated, revisiting the theory of coupled Tomonaga-Luttinger liquids. We identify susceptibilities as the key-parameters to govern exponents and Rashba precession lengths. In semiconducting quantum wires spins of different transport channels are found to {\em dephase} in their respective precession angles with respect to one another, as a result of the interaction. This could explain the experimental difficulty to realize the Datta Das transistor. In single walled carbon nanotubes, on the other hand, interactions are predicted to suppress dephasing between the two flavor modes at small doping.
Flat bands and long range Coulomb interactions: conducting or insulating?
Wolfgang Husler
Physics , 2014, DOI: 10.1103/PhysRevB.91.041102
Abstract: Dispersionless (flat) electronic bands are investigated regarding their conductance properties. Due to "caging" of carriers these bands are usually insulating at partial filling, at least on the non-interacting level. Considering the specific example of a $\mathcal{T}_3$--lattice we study long-range Coulomb interactions. A non-trivial dependence of the conductivity on flat band filling is obtained, exhibiting an infinite number of zeros. Near these zeros, the conductivity rises linearly with carrier density. At densities half way in between adjacent conductivity-zeros, strongly enhanced conductivity is predicted, accompanying a solid-solid phase transition.
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