Regression Mixture Models: Does Modeling the Covariance Between Independent Variables and Latent Classes Improve the Results?

Regression mixture models are increasingly used as an exploratory approach to identify heterogeneity in the effects of a predictor on an outcome. In this simulation study, we tested the effects of violating an implicit assumption often made in these models; that is, independent variables in the model are not directly related to latent classes. Results indicate that the major risk of failing to model the relationship between predictor and latent class was an increase in the probability of selecting additional latent classes and biased class proportions. In addition, we tested whether regression mixture models can detect a piecewise relationship between a predictor and outcome. Results suggest that these models are able to detect piecewise relations but only when the relationship between the latent class and the predictor is included in model estimation. We illustrate the implications of making this assumption through a reanalysis of applied data examining heterogeneity in the effects of family resources on academic achievement. We compare previous results (which assumed no relation between independent variables and latent class) to the model where this assumption is lifted. Implications and analytic suggestions for conducting regression mixture based on these findings are noted.     

Optimisation of phase ratio in the triple jump using computer simulation

The triple jump is an athletic event comprising three phases in which the optimal proportion of each phase to the total distance jumped, termed the phase ratio, is unknown. This study used a whole-body torque-driven computer simulation model of all three phases of the triple jump to investigate optimal technique. The technique of the simulation model was optimised by varying torque generator activation parameters using a Genetic Algorithm in order to maximise total jump distance, resulting in a hop-dominated technique (35.7%:30.8%:33.6%) and a distance of 14.05 m. Optimisations were then run with penalties forcing the model to adopt hop and jump phases of 33%, 34%, 35%, 36%, and 37% of the optimised distance, resulting in total distances of: 13.79 m, 13.87 m, 13.95 m, 14.05 m, and 14.02 m; and 14.01 m, 14.02 m, 13.97 m, 13.84 m, and 13.67 m respectively. These results indicate that in this subject-specific case there is a plateau in optimum technique encompassing balanced and hop-dominated techniques, but that a jump-dominated technique is associated with a decrease in performance. Hop-dominated techniques are associated with higher forces than jump-dominated techniques; therefore optimal phase ratio may be related to a combination of strength and approach velocity.     

Connecting the dots between fantasy and reality: The social psychology of our engagement with fictional narrative and its functional value

This essay provides an overview of research and theory on narrative and its important, functional role in human experience, including the ways people use media to interrogate their own beliefs and feelings, and derive social meaning. Thought‐provoking film, television, and books can help us make meaning of our lives and grow in ways that are important for our successful social functioning. Research reviewed here demonstrates that exposure to fiction can increase empathy and social skills and reduce prejudice. Our connection to characters and stories has been studied in various ways as extensions of the self into another, while at the same time bringing the other into the self. Bringing together disparate perspectives, we propose that connecting to story worlds involves a process of “dual empathy”—simultaneously engaging in intense personal processing while also “feeling through” characters, both of which produce benefits. Because the value of entertainment narratives may not always be well understood, we explain how those experiences can be personal, social, and can serve important adaptive functions.     

Is the “hot‐hands” phenomenon a misperception of random events?

T. Gilovich, R. Vallone, and A. Tversky (1985) asked whether the so-called hot-hands phenomenon – a temporary elevation of the probability of successful shots – actually exists in basketball. They concluded that hot-hands are misperceived random events. This paper re-examines the truth of their conclusion. The present study's main concern was the sensitivity of the statistical tests used in Gilovich et al.'s research. Simulated records of shots over a season were used. These represented many different situations and players, but they always contained at least one hot-hand period. The issue was whether Gilovich et al.'s tests were sensitive enough to detect the hot-hands embedded in the records. The study found that this sensitivity depends on the frequency of hot-hand periods, the total number of shots in all hot-hand periods, the number of shots in each hot-hand period, and the size of the increase in the probability of successful shots in hot-hand periods. However, when the values of those variables were set realistically, on average the tests could detect only about 12% of the hot-hands phenomena.     

Quantified Propositional Logic and the Number of Lines of Tree-Like Proofs

There is an exponential speed-up in the number of lines of the quantified propositional sequent calculus over Substitution Frege Systems, if one considers proofs as trees. Whether this is true also for the number of symbols, is still an open problem. This revised version was published online in June 2006 with corrections to the Cover Date.     

Mental Simulation, Affect, and Personality: A Conceptual Framework

Recent advances in theory and research on the relations among mental simulation, affect, and personality are summarized and combined. Research has shown that (a) affect and mental simulations can influence each other, (b) mental simulations can serve diverse self-motives, and (c) personality characteristics are related to divergent functions of mental simulations. Findings in these three areas are synthesized into a conceptual framework on the basis of three attributes of mental simulations: (a) time, whether simulations are prospective or retrospective; (b) direction, whether simulations are upward or downward; and (c) focus, whether simulations are contrasted or assimilated. This integrated framework not only may enable a greater understanding of existing findings, but also suggests novel and unique predictions for future research on understanding personality processes, automaticity in simulations, and coping with life events.     

消费行为研究中的联合分析法

联合分析(Conjoint Analysis)是一种定量的研究消费者选择偏好的方法。虽然从它诞生到现在只有40年的历史,但它对消费者行为学的影响很大,它的发展更是日新月异。文章首先介绍了联合分析的基本概念,然后重点阐述了联合分析的原理、步骤和发展历程,最后对联合分析的发展方向作了一个简要概括。     

Analysing multisource feedback with multilevel structural equation models: Pitfalls and recommendations from a simulation study

When multisource feedback instruments, for example, 360-degree feedback tools, are validated, multilevel structural equation models are the method of choice to quantify the amount of reliability as well as convergent and discriminant validity. A non-standard multilevel structural equation model that incorporates self-ratings (level-2 variables) and others’ ratings from different additional perspectives (level-1 variables), for example, peers and subordinates, has recently been presented. In a Monte Carlo simulation study, we determine the minimal required sample sizes for this model. Model parameters are accurately estimated even with the smallest simulated sample size of 100 self-ratings and two ratings of peers and of subordinates. The precise estimation of standard errors necessitates sample sizes of 400 self-ratings or at least four ratings of peers and subordinates. However, if sample sizes are smaller, mainly standard errors concerning common method factors are biased. Interestingly, there are trade-off effects between the sample sizes of self-ratings and others’ ratings in their effect on estimation bias. The degree of convergent and discriminant validity has no effect on the accuracy of model estimates. The χ² test statistic does not follow the expected distribution. Therefore, we suggest using a corrected level-specific standardized root mean square residual to analyse model fit and conclude with further recommendations for applied organizational research.     

Can imagined intergroup contact change (internal) dialogues on differences between ingroup and outgroup?

Several positive functions have been ascribed to integrative internal dialogues (IDs), which are based on mutual openness to a partner's viewpoint and a readiness to consider his/her arguments in order to potentially modify one's own stance. As the technique of imagined intergroup contact (IIC) favorably influences attitudes towards outgroup members, it was hypothesized that IIC would have a beneficial impact on IDs with an outgroup member when the dialogue is focused on differences between ingroup and outgroup. In the experiment, 151 people (80 women) participated. It revealed that after IIC, both the dialogue author's confrontational attitude and the interlocutor's integrative attitude decreased. Thus, IIC made participants less inclined to gain an advantage over their imagined outgroup interlocutors and more inclined to give them freedom in IDs. However, the effect was significant only when the author's involvement in ID was high or medium.     

Validation of a reflective thinking instrument for third-year undergraduate nursing students participating in high-fidelity simulation

Background: nursing students are required to think reflectively in both real and simulated clinical practice. Although the Reflective Thinking instrument is reliable in its measurement of reflective thinking, its validity is unknown. Method: confirmatory factor analysis was undertaken in an iterative manner within a non-equivalent control-group study to measure nursing students’ reflective thinking and satisfaction with high-fidelity simulation. The validity and reliability of the Reflective Thinking instrument was tested. Results: the resulting instrument consisted of 15 items across four factors. The final model was plausible as it demonstrated ‘goodness of fit’; however, it had neither convergent or discriminatory validity, nor reliability. Internal consistency was fair to reasonable for the four subscales. Conclusion: the testing of the Reflective Thinking instrument using confirmatory factor analysis is a vital initial step in the modification of this instrument. Further development using exploratory factor analysis will enhance the instrument’s relevance within high-fidelity simulation.