A Comparison of ML,WLSMV, and Bayesian Methods for Multilevel Structural Equation Models in Small Samples: A Simulation Study

Multilevel structural equation models are increasingly applied in psychological research. With increasing model complexity, estimation becomes computationally demanding, and small sample sizes pose further challenges on estimation methods relying on asymptotic theory. Recent developments of Bayesian estimation techniques may help to overcome the shortcomings of classical estimation techniques. The use of potentially inaccurate prior information may, however, have detrimental effects, especially in small samples. The present Monte Carlo simulation study compares the statistical performance of classical estimation techniques with Bayesian estimation using different prior specifications for a two-level SEM with either continuous or ordinal indicators. Using two software programs (Mplus and Stan), differential effects of between- and within-level sample sizes on estimation accuracy were investigated. Moreover, it was tested to which extent inaccurate priors may have detrimental effects on parameter estimates in categorical indicator models. For continuous indicators, Bayesian estimation did not show performance advantages over ML. For categorical indicators, Bayesian estimation outperformed WLSMV solely in case of strongly informative accurate priors. Weakly informative inaccurate priors did not deteriorate performance of the Bayesian approach, while strong informative inaccurate priors led to severely biased estimates even with large sample sizes. With diffuse priors, Stan yielded better results than Mplus in terms of parameter estimates.     

The role of sensory-motor modality compatibility in language processing

Language processing requires the combination of compatible (auditory-vocal and visual-manual) or incompatible (auditory-manual and visual-vocal) sensory-motor modalities, and switching between these sensory-motor modality combinations is very common in every-day life. Sensory-motor modality compatibility is defined as the similarity of stimulus modality and the modality of response-related sensory consequences. We investigated the influence of sensory-motor modality compatibility during performing language-related cognitive operations on different linguistic levels. More specifically, we used a variant of the task-switching paradigm, in which participants had to switch between compatible or between incompatible sensory-motor modality combinations during a verbal semantic categorization (Experiment 1) or during a word-form decision (Experiment 2). The data show higher switch costs (i.e., higher reaction times and error rates in switch trials compared to repetition trials) in incompatible sensory-motor modality combinations than in compatible sensory-motor modality combinations. This was true for every language-related cognitive operation, regardless of the individual linguistic level. Taken together, the present study demonstrates that sensory-motor modality compatibility plays an important role in modality switching during language processing.     

Results of nuclear medical, electroencephalographic, and angiographic examinations after brain tumor operations]

The methods of nuclear medicine and electro-encephalography allow, in combination, in almost every case the answer to the question of the cerebral tumour relapse. Our evaluation confirms the discovery of the greater sensitivity of the isotopic methods with relapses of glioblastomas, while relapses of meningiomas, astrocytomas, oligodendrogliomas and spongioblastomas can be recognized more frequently only by electro-encephalographic methods. The value of angiography is limited in cases of cerebral tumour relapses without pathological vascularisation, since the swelling can spread in the resection cavity without retroaction on the surrounding areas. For this reason vascular displacement (an only be observed very late on. Clinical judgement is furthermore complicated by the fact that after the removal of the primary tumour, often no reposition of the arteries ensues. After our exainations, a negative angiographic condition can be rule out a diagnosis of a relapse which has been established by electro-encephaolographic and isotopic methods.     

Antidromal sensory potential--a method of recording and normal values

A brief review is given of the literature dealing with the antidromic sensory potential and the different values attached to it. Methods of deriving this potential are described, and normal values for the antidromic sensory nerve conduction velocity are given.     

Results of catamnestic studies on the social prognosis of childhood epilepsies

Owing to the progress in pharmakotherapy the individual prognosis of epilepsy is characterized above all by brainorganic or psychoreactive caused disorders of the adaptability. The results of the examination of 153 children are presented, which were stationary treated for epilepsy. The special problems in the family, the school and in the choice of a job are referred.     

Value of various social and biological risk factors in child development

The medical reports of 400 children stationarilly treated for several symptoms and syndromes of abnormal behavior were evaluated. Especially important social factors are the in complete family and disorders of the parent-child-relations as well as the insufficient over-coming of educational problems. Children with results from infantile brain damage are especially endangered by a failure of compensation.     

Modified recording procedure for the determination of I/t-curves with arterial pulse recording and acoustic signal generation

I/t-curves were derived by means of a piezo-electric transducer. To receive the minimum responses more than just optically, an amplifier, which was coupled to a transducer, generated an acoustic signal. This modified technique serves to objectivity of the minimum response, which is important in the recording of the I/t-curves. As has been shown in a great number of tests, this procedure has proved to be useful in practice.     

The role of crosstalk in dual-task performance: evidence from manipulating response-code overlap

The present study examined the role of crosstalk in dual-task interference using a combination of a nonspeeded visual task and an auditory-manual reaction time (RT) task. The potential for dual-task crosstalk was introduced by presenting in the visual task objects (e.g., a cup with a handle), which “afford” associated responses that were either spatially compatible or incompatible with the response in the RT task. Crucially, the degree of crosstalk was varied by instructing participants either to attend to the left–right orientation of the objects, creating explicit cross-task response-code overlap (“strong crosstalk”), or to attend to object identity (no direct overlap; “weak crosstalk”). The data indicated a relative benefit for cross-task compatible trials, which was much greater with strong crosstalk than with weak crosstalk. Crucially, however, even on compatible trials dual-task performance was substantially worse with strong crosstalk than with weak crosstalk. This overall cost of crosstalk suggests interference of response codes even on compatible dual-task trials. This work was presented in August 2007 at the XVth Conference of the European Society for Cognitive Psychology (ESCoP) in Marseille, France. The author would like to thank Peter A. Frensch and two anonymous reviewers for helpful comments, Julia Klotz and Marion Marksteiner for testing the participants, and Lynn Huestegge for helpful discussions.