Measurement and structural invariance of cognitive ability tests after computer-based training

Ability tests are core elements in performance research as well as in applied contexts and are increasingly carried out using computer-based versions. In the last few decades a whole training and coaching industry has developed to prepare individuals for computer-based assessments. Evidence suggests that such commercial training programs can result in score gains in ability tests, thereby creating an advantage for those who can afford it and challenging the fairness of ability assessment. As a consequence, several authors recommended freely offering training software to all participants to increase measurement fairness. However, it is still an open question whether the unsupervised use of training software could have an impact on the measurement properties of ability tests. The goal of the present study is to fill this gap by examining the subjects’ ability scores for measurement and structural invariance across different amounts of computer-based training. Structural equation modeling was employed in a sample of 15,752 applicants who participated in high-stakes assessments with computer-based ability tests. Across different training amounts, our analyses supported measurement and structural invariance of ability scores. In conclusion, free training software is a means that provides fair preparation opportunities without changing the measurement properties of the tests

Measurement and structural invariance of cognitive ability tests after computer-based training

Ability tests are core elements in performance research as well as in applied contexts and are increasingly carried out using computer-based versions. In the last few decades a whole training and coaching industry has developed to prepare individuals for computer-based assessments. Evidence suggests that such commercial training programs can result in score gains in ability tests, thereby creating an advantage for those who can afford it and challenging the fairness of ability assessment. As a consequence, several authors recommended freely offering training software to all participants to increase measurement fairness. However, it is still an open question whether the unsupervised use of training software could have an impact on the measurement properties of ability tests. The goal of the present study is to fill this gap by examining the subjects’ ability scores for measurement and structural invariance across different amounts of computer-based training. Structural equation modeling was employed in a sample of 15,752 applicants who participated in high-stakes assessments with computer-based ability tests. Across different training amounts, our analyses supported measurement and structural invariance of ability scores. In conclusion, free training software is a means that provides fair preparation opportunities without changing the measurement properties of the tests

Multitrophic diversity in a biodiverse forest is highly nonlinear across spatial scales

Date of Acceptance: 10/11/2015 Acknowledgements We thank the administration of the Gutianshan National Nature Reserve and members of the BEF-China consortium for support, the many people involved in the plant and arthropod censuses, and T. Fang, S. Chen, T. Li, M. Ohl and C.-D. Zhu for help with species identification. G. Seidler kindly calculated forest cover and T. Scholten and P. Kühn provided soil data. The study was funded by the German Research Foundation (DFG FOR 891/1, 891/2), the Sino-German Centre for Research Promotion (GZ 524, 592, 698, 699, 785 and 1020) and the National Science Foundation of China (NSFC 30710103907 and 30930005).Peer reviewedPublisher PD

On/off switching of bit readout in bias-enhanced tunnel magneto-Seebeck effect

Böhnke A, Milnikel M, von der Ehe M, et al. On/off switching of bit readout in bias-enhanced tunnel magneto-Seebeck effect. Scientific Reports. 2015;5(1): 8945.Thermoelectric effects in magnetic tunnel junctions are promising to serve as the basis for logic devices or memories in a ”green” information technology. However, up to now the readout contrast achieved with Seebeck effects was magnitudes smaller compared to the well-established tunnel magnetoresistance effect. Here, we resolve this problem by demonstrating that the tunnel magneto-Seebeck effect (TMS) in CoFeB/MgO/CoFeB tunnel junctions can be switched on to a logic “1” state and off to “0” by simply changing the magnetic state of the CoFeB electrodes. This new functionality is achieved by combining a thermal gradient and an electric field. Our results show that the signal crosses zero and can be adjusted by tuning a bias voltage that is applied between the electrodes of the junction; hence, the name of the effect is bias-enhanced tunnel magneto-Seebeck effect (bTMS). Via the spin- and energy-dependent transmission of electrons in the junction, the bTMS effect can be configured using the bias voltage with much higher control than the tunnel magnetoresistance and even completely suppressed for only one magnetic configuration. Moreover, our measurements are a step towards the experimental realization of high TMS ratios without additional bias voltage, which are predicted for specific Co-Fe compositions

Multitrophic diversity in a biodiverse forest is highly nonlinear across spatial scales

Subtropical and tropical forests are biodiversity hotspots, and untangling the spatial scaling of their diversity is fundamental for understanding global species richness and conserving biodiversity essential to human well-being. However, scale-dependent diversity distributions among coexisting taxa remain poorly understood for heterogeneous environments in biodiverse regions. We show that diversity relations among 43 taxa - including plants, arthropods and microorganisms - in a mountainous subtropical forest are highly nonlinear across spatial scales. Taxon-specific differences in β-diversity cause under- or overestimation of overall diversity by up to 50% when using surrogate taxa such as plants. Similar relationships may apply to half of all (sub)tropical forests - including major biodiversity hotspots - where high environmental heterogeneity causes high biodiversity and species turnover. Our study highlights that our general understanding of biodiversity patterns has to be improved - and that much larger areas will be required than in better-studied lowland forests - to reliably estimate biodiversity distributions and devise conservation strategies for the world's biodiverse regions

Reliability of Therapist Effects in Practice-Based Psychotherapy Research : A Guide for the Planning of Future Studies

This paper aims to provide researchers with practical information on sample sizes for accurate estimations of therapist effects (TEs). The investigations are based on an integrated sample of 48,648 patients treated by 1800 therapists. Multilevel modeling and resampling were used to realize varying sample size conditions to generate empirical estimates of TEs. Sample size tables, including varying sample size conditions, were constructed and study examples given. This study gives an insight into the potential size of the TE and provides researchers with a practical guide to aid the planning of future studies in this field