On the Identifiability of 3- and 4-Parameter Item Response Theory Models From the Perspective of Knowledge Space Theory.

The present work aims at showing that the identification problems (here meant as both issues of empirical indistinguishability and unidentifiability) of some item response theory models are related to the notion of identifiability in knowledge space theory. Specifically, that the identification problems of the 3- and 4-parameter models are related to the more general issues of forward- and backward-gradedness in all items of the power set, which is the knowledge structure associated with IRT models under the assumption of local independence. As a consequence, the identifiability problem of a 4-parameter model is split into two parts: a first one, which is the result of a trade-off between the left-side added parameters and the remainder of the Item Response Function, e.g., a 2-parameter model, and a second one, which is the already well-known identifiability issue of the 2-parameter model itself. Application of the results to the logistic case appears to provide both a confirmation and a generalization of the current findings in the literature for both fixed- and random-effects IRT logistic models.

Patients' well-being during the transition period after psychiatric hospitalization to school: insights from an intensive longitudinal assessment of patient-parent-teacher triads.

BACKGROUND: The transition period after psychiatric hospitalization back to school is accompanied by various challenges, including a substantial risk for rehospitalization. Self-efficacy and self-control, as transdiagnostic variables and important predictors of coping with school demands, should be crucial factors for successful adaptation processes as well as an overall high well-being during school reentry. The present study therefore investigates how patients' well-being develops during this period, and how it is related to patients' self-control and academic self-efficacy, as well as parents' and teachers' self-efficacy in dealing with the patient. METHODS: In an intensive longitudinal design, daily ambulatory assessment measures via smartphone were collected with self-reports from the triadic perspective of 25 patients (Mage = 10.58 years), 24 parents, and 20 teachers on 50 consecutive school days, starting 2 weeks before discharge from a psychiatric day hospital (mean compliance rate: 71% for patients, 72% for parents and 43% for teachers). Patients answered daily questions between five and nine o'clock in the evening about their well-being, self-control, academic self-efficacy and about positive and negative events at school, as well as parents and teachers about their self-efficacy in dealing with the patient. RESULTS: Multilevel modeling revealed that on average, patients' well-being and self-control decreased during the transition period, with trends over time differing significantly between patients. While patients' academic self-efficacy did not systematically decrease over time, it did show considerable intra-individual fluctuation. Importantly, patients experienced higher well-being on days with higher self-control and academic self-efficacy as well as with higher parental self-efficacy. Daily teacher self-efficacy did not show a significant within-person relationship to daily patients' well-being. CONCLUSIONS: Well-being in the transition period is related to self-control and self-efficacy of patients and their parents. Thus, addressing patients' self-control and academic self-efficacy, as well as parental self-efficacy, seems promising to enhance and stabilize well-being of patients during transition after psychiatric hospitalization. Trial registration Not applicable, as no health care intervention was conducted.

Acute effects of a motor coordination intervention on executive functions in kindergartners: a proof-of-concept randomized controlled trial.

BACKGROUND: Executive functions are pivotal for future academic and social functioning. Causal effects of physical activity on executive functions have been shown in adults. The primary objective of this study was to test the proof-of-concept (i.e., feasibility of implementation and acceptance) of a motor coordination intervention and a sedentary control condition in kindergartners and its preliminary effectiveness on subsequent executive function performance. METHODS: The study used a two-group post-test only design. All children aged between 4 and 7 years old were eligible. One hundred and three children (46% girls; age: M = 5.71 years, 95% CI = 5.50 to 5.92) recruited in a middle-sized town in Germany were randomly assigned to a 20-min motor coordination intervention (n = 51) or a sedentary control condition (n = 52), both of which were conducted in a one-on-one experimenter-child setting in the university or kindergarten. A second blinded-to-condition experimenter assessed the executive function outcomes directly following the conditions. Proof-of-concept criteria were the implementation of the intervention with a moderate-to-vigorous physical activity level assessed via heart rate sensors, and with motor coordination demands, analyzed via video recordings; children's acceptance via self-reported enjoyment of the conditions; and the post-assessments of executive functions with a behavioral and computerized task. RESULTS: The motor coordination intervention and the control condition were feasible in a one-on-one setting with kindergartners. The intervention revealed heart rate increases and challenging motor coordination tasks. Children in both conditions indicated they enjoy them. Performance in the two executive function tasks did not differ between children in the motor coordination intervention and the control condition. CONCLUSIONS: A one-on-one experimenter-child setting was feasible to deliver in kindergartners. Future intervention studies should consider pre-testing of executive functions and take into account children's characteristics as potential moderators, such as motor coordination skills.

E-Mental-Health aftercare for children and adolescents after partial or full inpatient psychiatric hospitalization: study protocol of the randomized controlled DigiPuR trial.

BACKGROUND: During reintegration to daily school life following psychiatric hospitalization, children and adolescents are confronted with various challenges and are at risk for rehospitalization. Tailored post-discharge services could support a successful readjustment and accompany the high-risk transition period after discharge. The study DigiPuR ("Digital gestützte Psychotherapie und Reintegration," digitally supported psychotherapy and reintegration) aims to establish and to evaluate an innovative digital aftercare program to alleviate challenges during reintegration and improve cross-sectoral care. METHODS: DigiPuR is a randomized controlled trial comparing a digital aftercare service with regular aftercare (TAU) (planned N = 150, 25 children/adolescents, 25 parents, and 25 teachers in each group). In the intervention group, direct communication via secure and regular video calls until 8 weeks after discharge and a secure messenger system between the hospital, family, and school, as well as, if needed, external support systems, are established. A longitudinal pre-post-follow-up assessment at admission, discharge, and 8, 24, and 36 weeks after discharge takes place supplemented by a daily smartphone-based ambulatory assessment from a triadic perspective of patients, parents, and teachers. Primary outcomes include whether participants in the intervention group have fewer readmissions and higher treatment satisfaction and health-related quality of life as well as lower symptom severity than participants in the control group. DISCUSSION: The present study is essential to address the cross-sectoral challenges associated with reintegration into daily (school) life following child and adolescent psychiatric hospitalization and to determine possible needed adaptations in partial or full inpatient settings. If applicability and efficacy of the aftercare service can be demonstrated, integration into regular care will be sought. TRIAL REGISTRATION: ClinicalTrials.gov NCT04986228 . Registered on August 2, 2021.

Do Open-Science Badges Increase Trust in Scientists Among Undergraduates, Scientists, and the Public?

In three experimental studies, we investigated whether badges for open-science practices have the potential to affect trust in scientists and topic-specific epistemic beliefs by student teachers (n = 270), social scientists (n = 250), or the public (n = 257), all of whom were at least 16 years old. Furthermore, we analyzed the moderating role of epistemic beliefs for badges and trust. Each participant was randomly assigned to two of three conditions: badges awarded, badges not awarded, and no badges (control). In all samples, our Bayesian analyses indicated that badges influence trust as expected, with one exception in the public sample: An additional positive effect of awarded badges (compared with no badges) was not supported. For students and scientists, we found evidence for the relation of badges and epistemic beliefs as well as epistemic beliefs and trust. Further, we found evidence for the absence of moderation by epistemic beliefs.

Forecasting Intra-individual Changes of Affective States Taking into Account Inter-individual Differences Using Intensive Longitudinal Data from a University Student Dropout Study in Math.

The longitudinal process that leads to university student dropout in STEM subjects can be described by referring to (a) inter-individual differences (e.g., cognitive abilities) as well as (b) intra-individual changes (e.g., affective states), (c) (unobserved) heterogeneity of trajectories, and d) time-dependent variables. Large dynamic latent variable model frameworks for intensive longitudinal data (ILD) have been proposed which are (partially) capable of simultaneously separating the complex data structures (e.g., DLCA; Asparouhov et al. in Struct Equ Model 24:257-269, 2017; DSEM; Asparouhov et al. in Struct Equ Model 25:359-388, 2018; NDLC-SEM, Kelava and Brandt in Struct Equ Model 26:509-528, 2019). From a methodological perspective, forecasting in dynamic frameworks allowing for real-time inferences on latent or observed variables based on ongoing data collection has not been an extensive research topic. From a practical perspective, there has been no empirical study on student dropout in math that integrates ILD, dynamic frameworks, and forecasting of critical states of the individuals allowing for real-time interventions. In this paper, we show how Bayesian forecasting of multivariate intra-individual variables and time-dependent class membership of individuals (affective states) can be performed in these dynamic frameworks using a Forward Filtering Backward Sampling method. To illustrate our approach, we use an empirical example where we apply the proposed forecasting method to ILD from a large university student dropout study in math with multivariate observations collected over 50 measurement occasions from multiple students ([Formula: see text]). More specifically, we forecast emotions and behavior related to dropout. This allows us to predict emerging critical dynamic states (e.g., critical stress levels or pre-decisional states) 8 weeks before the actual dropout occurs.

Association of professional pre-qualifications, study success in medical school and the eligibility for becoming a physician: A scoping review.

BACKGROUND: Literature, individual experiences and common considerations suggest that prior professional qualification can be an advantage for later career development. For instance, in Germany, professional pre-qualification has been honored by medical faculties in selection procedures for several years. However, a systematic evaluation of this relationship lacks. This scoping review summarizes existing literature and addresses the role of prior professional pre-qualifications on objective or subjective study success and the choice of a specialization. METHODS: The scoping review was performed oriented on the PRISMA guidelines. PsycINFO and PubMed databases were searched for relevant studies that included data of medical students with and without professional pre-qualifications. To answer the underlying research questions, this scoping review also includes studies that examine professional pre-qualifications in association with non-cognitive "soft" criteria. RESULTS AND FURTHER DIRECTIONS: 1055 items were identified and reviewed by two independent reviewers with final 11 studies were included for this scoping review. The results of identified studies that report possible effects of prior pre-professional qualifications are inconclusive but suggest that prior professional qualifications tend not to have rather an advantage on study success. Medical school success for students with prior professional qualifications tended to be below average in the preclinical setting, and there were no differences in the clinical setting compared with students without prior professional qualifications. The influence of professional pre-qualifications has not yet been adequately studied without the moderator variable "waiting time" and "A-levels grade". The scoping review indicates insufficient number of articles stating a co-relation of prior pre-qualifications and subjective data. Again, the results found are not sufficient to state a clear relationship between professional pre-qualifications and the choice of a specific speciality preference. However, professional pre-qualifications, both in medicine and as "practical experience in rural areas", tend to be beneficial for the choice of becoming a rural physician. Large-scale cross-sectional and longitudinal studies are needed to investigate the influence of professional pre-qualifications on different study trajectory parameters.

Comparing estimators for latent interaction models under structural and distributional misspecifications.

Estimation methods for structural equation models with interactions of latent variables were compared in several studies. Yet none of these studies examined models that were structurally misspecified. Here, the model-implied instrumental variable 2-stage least square estimator (MIIV-2SLS; Bollen, 1995; Bollen & Paxton, 1998), the 2-stage method of moments estimator (2SMM; Wall & Amemiya, 2003), the nonlinear structural equation mixture model approach (NSEMM; Kelava, Nagengast, & Brandt, 2014), and the unconstrained product indicator approach (UPI; Marsh, Wen, & Hau, 2004) were compared in a Monte Carlo simulation. The design included structural misspecifications in the measurement model involving the scaling indicator or not, the size of the misspecification, normal and nonnormal data, the indicators' reliability, and sample size. For the structural misspecifications that did not involve the scaling indicator, we found that MIIV-2SLS' parameter estimates were less biased compared with 2SMM, NSEMM, and UPI. If the reliability was high, the RMSE for all approaches was very similar; for low reliability, MIIV-2SLS' RMSE became larger compared with the other approaches. If the structural misspecification involved the scaling indicator, all estimators were seriously biased, with the largest bias for MIIV-2SLS. In most scenarios, this bias was more severe for the linear effects than for the interaction effect. The RMSE for conditions with misspecified scaling indicators was smallest for 2SMM, especially for low reliability scenarios, but the overall magnitude of bias was such that we cannot recommend any of the estimators in this situation. Our article showed the damage done when researchers omit cross-loadings of the scaling indicator and the importance of giving more attention to these indicators particularly if the indicators' reliability is low. It also showed that no one estimator is superior to the others across all conditions. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The adolescent motor performance development of elite female soccer players: A study of prognostic relevance for future success in adulthood using multilevel modelling.

Considering the scarce empirical evidence regarding talent predictors in female youth soccer, the present study aimed to investigate the long-term prognostic validity of elite female soccer players' adolescent motor performance for future success in adulthood. Additionally, the three-year development of highly talented girls' motor performance and the predictive value of this motor development for reaching a professional adult performance level (APL) was analysed. Overall, N = 737 female players participated in nationwide motor diagnostics (sprinting, agility, dribbling, ball control, shooting) within the German Soccer Association's talent identification and development programme at least twice between the age groups Under-12 (U12) and U15. Based on their APL at least four years later, participants were assigned to a professional (first German division, 6.2%) or non-professional group (lower divisions, 93.8%). Multilevel regression analyses revealed a general prognostic relevance for the investigated parameters with respect to players' APL. In addition, there was a non-linear improvement in participants' motor performance across all variables from U12 to U15. However, non-significant interactions between APL and these improvements indicate motor performance development itself cannot adequately predict players' future success in adulthood. Findings provide insightful information that can help coaches foster optimal support for young female soccer players' development.

Refining scores based on patient reported outcomes - statistical and medical perspectives.

BACKGROUND: Patient Reported Outcomes (PRO) are gaining more and more importance in the context of clinical trials. The assessment of PRO is frequently performed by questionnaires where the multiple items of a questionnaire are usually pooled within summarizing scores. These scores are used as variables to measure subjective aspects of treatments and diseases. In clinical research, the calculation of these scores is mostly kept very simple, e.g. by a simple summation of item values. In the medical literature, there is hardly any guidance for performing a refinements of questionnaires and for deducing adequate scores. In contrast, in psychometric literature, there are plenty of more sophisticated methods, which overcome typical assumptions made in traditional (sum) scores, however to the prize of more complicated algorithms, which might be difficult to communicate. When faced with the practical task to refine an existing questionnaire, there exist a clear gap of guidance for applied medical researchers. By this article we try to fill this important gap between psychometric theory and medical application by illustrating our methodological choices on the example of a clinical PRO questionnaire. METHODS: Based on our experiences with the refinement of the BCTOS, a PRO questionnaire to assess aesthetic and function after breast conserving therapy in breast cancer patients, we present the following general steps that we performed by refining the BCTOS questionnaire and its scores: 1. Refinement of the length of the questionnaire and the (item-factor) structure. 2. Selection of the factor score estimation method. 3. Validation of the refined questionnaire and scores with respect to validity, reliability and structure based on a validation cohort. RESULTS: Our step-step-step procedure helped us to shorten the current form of the BCTOS and to redefine the factor structure. By this, the compliance of patients can be increased and the interpretation of the results becomes more coherent. CONCLUSIONS: We present a step-by-step procedure to refine an existing medical questionnaire along with its scores illustrated and discussed by the refinement of the BCTOS. TRIAL REGISTRATION: Due to the character of the study (no intervention study), no registration was performed.

On a Generalization of Local Independence in Item Response Theory Based on Knowledge Space Theory.

Knowledge space theory (KST) structures are introduced within item response theory (IRT) as a possible way to model local dependence between items. The aim of this paper is threefold: firstly, to generalize the usual characterization of local independence without introducing new parameters; secondly, to merge the information provided by the IRT and KST perspectives; and thirdly, to contribute to the literature that bridges continuous and discrete theories of assessment. In detail, connections are established between the KST simple learning model (SLM) and the IRT General Graded Response Model, and between the KST Basic Local Independence Model and IRT models in general. As a consequence, local independence is generalized to account for the existence of prerequisite relations between the items, IRT models become a subset of KST models, IRT likelihood functions can be generalized to broader families, and the issues of local dependence and dimensionality are partially disentangled. Models are discussed for both dichotomous and polytomous items and conclusions are drawn on their interpretation. Considerations on possible consequences in terms of model identifiability and estimation procedures are also provided.

Identification of neurophysiological biotypes in attention deficit hyperactivity disorder.

AIM: Findings on neurophysiological alterations in attention deficit hyperactivity disorder (ADHD) have been proposed to underlie ADHD symptoms, with different etiological pathways for different patient biotypes. We aimed at determining whether neurophysiological deviations confirm distinct neurophysiological profiles in ADHD, thus providing direct evidence for the endophenotype concept. METHODS: Neurophysiological biotypes were investigated in 87 adult patients with ADHD using cluster analysis. Parameters fed into the analysis comprised both hemodynamic and electrophysiological data. To validate results, the independent variables of the clusters were compared with healthy controls. RESULTS: Cluster analysis yielded three neurophysiologically based ADHD biotypes showing: (i) above-average functioning in attention allocation; (ii) difficulties in attention allocation and inhibitory control but elevated frontal activation during a working memory task; and (iii) functional impairments in state regulation. CONCLUSION: Classifying patients with ADHD into neurophysiological biotypes sheds light on etiological pathways, with implications for diagnostics and (individualized) treatment options.

Longitudinal motor performance development in early adolescence and its relationship to adult success: An 8-year prospective study of highly talented soccer players.

Several talent identification and development (TID) programs in soccer have implemented diagnostics to measure players' motor performance. Yet, there is a lack of research investigating the relationship between motor development in adolescence and future, adult performance. This longitudinal study analyzed the three-year development of highly talented young soccer players' speed abilities and technical skills and examined the relevance of this development to their adult success. The current research sample consisted of N = 1,134 players born between 1993 and 1995 who were selected for the German Soccer Association's TID program and participated in nationwide motor diagnostics (sprinting, agility, dribbling, ball control, shooting) four times between the Under 12 (U12) and Under 15 (U15) age class. Relative age (RA) was assessed for all players, and a total motor score was calculated based on performances in the individual tests. In order to investigate players' future success, participants were divided into two groups according to their adult performance level (APL) in the 2014/2015 season: Elite (1st-5th German division; N = 145, 12.8%) and non-elite players (lower divisions; N = 989, 87.2%). Using multilevel regression analyses each motor performance was predicted by Time, Time2 (level-1 predictors), APL, and RA (level-2 covariates) with simultaneous consideration for interaction effects between the respective variables. Time and Time2 were significant predictors for each test performance. A predictive value for RA was confirmed for sprinting and the total motor score. A significant relationship between APL and the motor score as well as between APL and agility, dribbling, ball control, and shooting emerged. Interaction effects distinctly failed to reach significance. The study found a non-linear improvement in players' performance for all considered motor performance factors over a three-year period from early to middle adolescence. While their predictive value for future success was confirmed by a significant relationship between APL and most of the considered factors, there was no significant interaction between APL and Time. These findings indicate that future elite players had already been better at the beginning of the TID program and maintained this high level throughout their promotion from U12 to U15.

Tilt testing and what you should know about it - Experience with 835 consecutive patients with syncope of unknown origin.

BACKGROUND: Numerous tilt testing protocols with and without a preceding passive phase or the administration of nitrates have already been investigated. However, a truely standardized method for the investigation does not yet exist. METHODS AND RESULTS: A total of 835 consecutive patients who underwent tilt testing between January 2005 and March 2015 were included in this study. Results of a passive tilt test (PTT), a nitrate-stimulated tilt test (NSTT) with a preceding passive phase of 20 min, or an early nitrate-stimulated tilt test (ENSTT) without a preceding passive phase were compared and analyzed retrospectively in 735 patients. In addition, a further 100 consecutive patients were prospectively randomized 1:1 to compare NSTT and ENSTT. In the retrospective analysis, 38% of the patients in the ENSTT group had a positive test response compared with 45% in the NSTT group and only 27% in the PTT group (p = 0.0002). In the prospective study, 34% of the patients had a positive test response in the ENSTT group compared with 42% in the NSTT group (p = 0.537). The mean duration to a positive test response was significantly shorter in the ENSTT group (retrospective and prospective p < 0.001). The nitrate-stimulated groups did not differ significantly with respect to the hemodynamic characteristics of a positive test response (retrospective: p = 0.773; prospective: p = 0.086). CONCLUSION: Due to the rate of positive test response being comparable to other protocols and its significantly shorter test duration, nitrate-stimulated tilt testing without a preceding passive tilt test may be favored for use in a busy clinical practice.

Development and psychometric validation of a shorter version of the Breast Cancer Treatment Outcome Scale (BCTOS-12).

OBJECTIVES: Aesthetic and functional outcomes after oncoplastic breast-conserving surgery (BCS) are directly related to the patients' quality of life (QoL). The Breast Cancer Treatment Outcome Scale (BCTOS) is a validated but burdensome questionnaire for the assessment of these outcomes. The aim of the study was to strengthen and focus the BCTOS instrument by reducing the number of items and subscales without loss of information and validity. METHODS: This study used a dataset of 871 patients with stage 0 - III breast cancer, from a prospective cohort study, who underwent BCS. We investigated correlations and other criteria of homogeneity of the BCTOS items to identify redundancies. An exploratory factor analysis was used to remodel the item-factor structure. Correlation and linear regression analysis with validated QoL subscales assessed the convergent and discriminant validity of the modified BCTOS structure. RESULTS: The factor analysis revealed two distinct subscales for aesthetic and functional outcomes. It was possible to reduce the 22 items of the original BCTOS to 12 items, thus the "BCTOS-12". The two new scales had very good internal consistency: Cronbach's α = 0.86 for the new Aesthetic Status subscale and α = 0.81 for the new Functional Status subscale. Bootstrapping confirmed the item-factor structure for all 10,000 samples, remarkably. CONCLUSION: The modified BCTOS questionnaire with only 12 items (BCTOS-12) is shorter, easier to interpret, and shows good validity.

Affective Aspects of Perceived Loss of Control and Potential Implications for Brain-Computer Interfaces.

Most brain-computer interfaces (BCIs) focus on detecting single aspects of user states (e.g., motor imagery) in the electroencephalogram (EEG) in order to use these aspects as control input for external systems. This communication can be effective, but unaccounted mental processes can interfere with signals used for classification and thereby introduce changes in the signal properties which could potentially impede BCI classification performance. To improve BCI performance, we propose deploying an approach that potentially allows to describe different mental states that could influence BCI performance. To test this approach, we analyzed neural signatures of potential affective states in data collected in a paradigm where the complex user state of perceived loss of control (LOC) was induced. In this article, source localization methods were used to identify brain dynamics with source located outside but affecting the signal of interest originating from the primary motor areas, pointing to interfering processes in the brain during natural human-machine interaction. In particular, we found affective correlates which were related to perceived LOC. We conclude that additional context information about the ongoing user state might help to improve the applicability of BCIs to real-world scenarios.

The influence of speed abilities and technical skills in early adolescence on adult success in soccer: A long-term prospective analysis using ANOVA and SEM approaches.

Several talent development programs in youth soccer have implemented motor diagnostics measuring performance factors. However, the predictive value of such tests for adult success is a controversial topic in talent research. This prospective cohort study evaluated the long-term predictive value of 1) motor tests and 2) players' speed abilities (SA) and technical skills (TS) in early adolescence. The sample consisted of 14,178 U12 players from the German talent development program. Five tests (sprint, agility, dribbling, ball control, shooting) were conducted and players' height, weight as well as relative age were assessed at nationwide diagnostics between 2004 and 2006. In the 2014/15 season, the players were then categorized as professional (n = 89), semi-professional (n = 913), or non-professional players (n = 13,176), indicating their adult performance level (APL). The motor tests' prognostic relevance was determined using ANOVAs. Players' future success was predicted by a logistic regression threshold model. This structural equation model comprised a measurement model with the motor tests and two correlated latent factors, SA and TS, with simultaneous consideration for the manifest covariates height, weight and relative age. Each motor predictor and anthropometric characteristic discriminated significantly between the APL (p < .001; η2 ≤ .02). The threshold model significantly predicted the APL (R2 = 24.8%), and in early adolescence the factor TS (p < .001) seems to have a stronger effect on adult performance than SA (p < .05). Both approaches (ANOVA, SEM) verified the diagnostics' predictive validity over a long-term period (≈ 9 years). However, because of the limited effect sizes, the motor tests' prognostic relevance remains ambiguous. A challenge for future research lies in the integration of different (e.g., person-oriented or multilevel) multivariate approaches that expand beyond the "traditional" topic of single tests' predictive validity and toward more theoretically founded issues.

The Standardization of Linear and Nonlinear Effects in Direct and Indirect Applications of Structural Equation Mixture Models for Normal and Nonnormal Data.

The application of mixture models to flexibly estimate linear and nonlinear effects in the SEM framework has received increasing attention (e.g., Jedidi et al., 1997b; Bauer, 2005; Muthén and Asparouhov, 2009; Wall et al., 2012; Kelava and Brandt, 2014; Muthén and Asparouhov, 2014). The advantage of mixture models is that unobserved subgroups with class-specific relationships can be extracted (direct application), or that the mixtures can be used as a statistical tool to approximate nonnormal (latent) distributions (indirect application). Here, we provide a general standardization procedure for linear and nonlinear interaction and quadratic effects in mixture models. The procedure can also be applied to multiple group models or to single class models with nonlinear effects like LMS (Klein and Moosbrugger, 2000). We show that it is necessary to take nonnormality of the data into account for a correct standardization. We present an empirical example from education science applying the proposed procedure.

A general non-linear multilevel structural equation mixture model.

In the past 2 decades latent variable modeling has become a standard tool in the social sciences. In the same time period, traditional linear structural equation models have been extended to include non-linear interaction and quadratic effects (e.g., Klein and Moosbrugger, 2000), and multilevel modeling (Rabe-Hesketh et al., 2004). We present a general non-linear multilevel structural equation mixture model (GNM-SEMM) that combines recent semiparametric non-linear structural equation models (Kelava and Nagengast, 2012; Kelava et al., 2014) with multilevel structural equation mixture models (Muthén and Asparouhov, 2009) for clustered and non-normally distributed data. The proposed approach allows for semiparametric relationships at the within and at the between levels. We present examples from the educational science to illustrate different submodels from the general framework.

A new approach for the quantification of synchrony of multivariate non-stationary psychophysiological variables during emotion eliciting stimuli.

Emotion eliciting situations are accompanied by changes of multiple variables associated with subjective, physiological and behavioral responses. The quantification of the overall simultaneous synchrony of psychophysiological reactions plays a major role in emotion theories and has received increased attention in recent years. From a psychometric perspective, the reactions represent multivariate non-stationary intra-individual time series. In this paper, a new time-frequency based latent variable approach for the quantification of the synchrony of the responses is presented. The approach is applied to empirical data, collected during an emotion eliciting situation. The results are compared with a complementary inter-individual approach of Hsieh et al. (2011). Finally, the proposed approach is discussed in the context of emotion theories, and possible future applications and limitations are provided.