Commentary on Steinley and Brusco (2011): recommendations and cautions

I discuss the recommendations and cautions in Steinley and Brusco's (2011) article on the use of finite models to cluster a data set. In their article, much use is made of comparison with the K-means procedure. As noted by researchers for over 30 years, the K-means procedure can be viewed as a special case of finite mixture modeling in which the components are in equal (fixed) proportions and are taken to be normal with a common spherical covariance matrix. In this commentary, I pay particular attention to this link and to the use of normal mixture models with arbitrary component-covariance matrices.     

Hopes and cautions in implementing Bayesian structural equation modeling

Muthén and Asparouhov (2012) have proposed and demonstrated an approach to model specification and estimation in structural equation modeling (SEM) using Bayesian methods. Their contribution builds on previous work in this area by (a) focusing on the translation of conventional SEM models into a Bayesian framework wherein parameters fixed at zero in a conventional model can be respecified using small-variance priors and (b) implementing their approach in software that is widely accessible. We recognize potential benefits for applied researchers as discussed by Muthén and Asparouhov, and we also see a tradeoff in that effective use of the proposed approach introduces increased demands in terms of expertise of users to navigate new complexities in model specification, parameter estimation, and evaluation of results. We also raise cautions regarding the issues of model modification and model fit. Although we see significant potential value in the use of Bayesian SEM, we also believe that effective use will require an awareness of these complexities. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

回归混合模型：方法进展与软件实现

近来以个体为分析对象的方法日益受到研究者的重视, 其中潜类别和潜剖面模型最为流行。研究者在潜类别和潜剖面模型建模时往往需要进一步探讨协变量与潜分组之间的关系(即带有协变量的潜类别模型)。例如, 哪些变量预测个体类别归属, 以及个体的类别归属对结果变量的预测。本文对近年来研究者提出的各种方法进行了回顾和比较。包括当结果变量是分类变量的LTB法; 当结果变量是连续变量时的BCH和稳健三步法。在此基础上, 文章为应用研究者提供了Mplus软件示例, 并在最后对当前研究存在的问题和未来研究趋势进行了简要评价。     

Refining the borderline personality disorder phenotype through finite mixture modeling: implications for classification

Borderline personality disorder (BPD) is characterized by considerable heterogeneity. Prior approaches to resolving heterogeneity in BPD pathology have used factor and cluster analytic as well as latent class analysis strategies. These prior studies have been atheoretical in nature, but provide an initial empirical corpus for further sub-typing efforts in BPD. A model-based taxonomy for BPD that is supported by evidence from an advanced statistical methodology would enhance investigations of BPD etiology, pathophysiology, and treatment. This study applied finite mixture modeling analysis, in a model-guided fashion, to selected dimensions of pathology within a group of well-characterized BPD patients to determine if latent groups are harbored within the disorder. Subjects with BPD (N = 90) were examined on a variety of model-relevant psychopathology dimensions. We applied finite mixture modeling to these dimensions. We then evaluated the validity of the obtained solution by reference to a variety of external measures not included in the initial mixture modeling. Three phenotypically distinct groups reside within the overall BPD category. Group-1 is characterized by low levels of antisocial, paranoid, and aggressive features. Group-2 is characterized by elevated paranoid features, whereas Group-3 is characterized by elevated antisocial and aggressive features. External correlates reveal a pattern of differences consistent with the validity of this proposed grouping structure. A theory-guided finite mixture modeling analysis supports a parsing of the BPD category into three subgroups. This proposed BPD taxonomy represents an approach to reducing heterogeneity observed among BPD patients and it may prove useful in studies seeking to understand etiologic and pathophysiologic factors as well as treatment response in BPD.     

Detecting latent taxa: Monte Carlo comparison of taxometric, mixture model, and clustering procedures

A Monte Carlo evaluation of four procedures for detecting taxonicity was conducted using artificial data sets that were either taxonic or nontaxonic. The data sets were analyzed using two of Meehl's taxometric procedures, MAXCOV and MAMBAC, Ward's method for cluster analysis in concert with the cubic clustering criterion and a latent variable mixture modeling technique. Performance of the taxometric procedures and latent variable mixture modeling were clearly superior to that of cluster analysis in detecting taxonicity. Applied researchers are urged to select from the better procedures and to perform consistency tests.     

Culture and social distance: a case study of methodological cautions

The authors presented, as a case study of methodological challenges in cross-cultural research, E. S. Bogardus's (1925) Social Distance Scale, which requires respondents to indicate the social distance between themselves and others. The meaningfulness of the scale depends on the assumption that respondents believe that the magnitude of social distance increases as one moves through the social categories of family member, friend, neighbor, coworker, and citizen. The authors tested this assumption for English Canadian, French Canadian, Jewish, Indian, Algerian, and Greek participants, all 1st-generation immigrants in Montreal. The participants rated their willingness to associate with members of each of the other ethnic groups in 5 social categories. The percentage of respondents in each sample whose data conformed to the prediction ranged from 63.7% to 98.0%, with English Canadian, French Canadian, and Jewish respondents providing responses most consistent with the predicted pattern. The Indian and Algerian respondents' data were the least consistent with the predicted pattern, especially when rating members of their own ethnic groups.     

Working with the Holocaust victims psychologically: Some vital cautions

This article traces the evolution of a major psychological organization's involvement with the Holocaust as a fully justified and legitimate topic of concern and of an ongoing commitment to its study and memory. A number of important cautions and requirements are presented for mental health workers who wish to work in the areas encompassed by the Holocaust, including working therapeutically with Survivors of the Holocaust and their children. The special danger of diminishing or trivializing the Holocaust in the course of writing about aspects or elements of it in psychological articles or writings, as has been the case in other kinds of literature, is brought into focus.     

Asymptotic log-linear analysis: some cautions concerning sparse frequency tables

Traditional asymptotic probability values resulting from log-linear analyses of sparse frequency tables are often much too large. Asymptotic probability values for chi-squared and likelihood-ratio statistics are compared to nonasymptotic and exact probability values for selected log-linear models. The asymptotic probability values are all too often substantially larger than the exact probability values for the analysis of sparse frequency tables. An exact nondirectional permutation method is presented to analyze combined independent multinomial distributions. Exact nondirectional permutation methods to analyze hypergeometric distributions associated with r-way frequency tables are confined to r = 2.     

Evaluating video modeling and video modeling with video feedback to enhance the performance of competitive dancers

This study evaluated the use of video modeling and video modeling plus video feedback to enhance four adolescents' performance of a dance movement. Intervention was evaluated in a multiple baseline across participants design. This study found that video modeling enhanced performance from baseline, but the addition of video feedback produced further increases. For one participant, improvement was dependent on the perspective of the video model. Implications of these findings and suggestions for future research are discussed.     

Identifying trajectories of adolescent smoking: an application of latent growth mixture modeling.

The goal of the current study was to identify discrete longitudinal patterns of change in adolescent smoking using latent growth mixture modeling. Five distinct longitudinal patterns were identified. A group of early rapid escalators was characterized by early escalation (at age 13) that rapidly increased to heavy smoking. A pattern characterized by occasional puffing up until age 15, at which time smoking escalated to moderate levels was also identified (late moderate escalators). Another group included adolescents who, after age 15, began to escalate slowly in their smoking to light (0.5 cigarettes per month) levels (late slow escalators). Finally, a group of stable light smokers (those who smoked 1-2 cigarettes per month) and a group of stable puffers (those who smoked only a few puffs per month) were also identified. The stable puffer group was the largest group and represented 25% of smokers.     

Statistical and substantive checking in growth mixture modeling: comment on Bauer and Curran (2003)

This commentary discusses the D. J. Bauer and P. J. Curran (2003) investigation of growth mixture modeling. Single-class modeling of nonnormal outcomes is compared with modeling with multiple latent trajectory classes. New statistical tests of multiple-class models are discussed. Principles for substantive investigation of growth mixture model results are presented and illustrated by an example of high school dropout predicted by low mathematics achievement development in Grades 7-10.     

Suicidal Asian patients: recommendations for treatment

I was given an opportunity to learn how suicide prevention programs are administered in the United States. Not surprisingly, treatment for suicidal patients is conducted in terms of the basic tenets of Western culture. When American therapists are seeing Asian patients, especially suicidal individuals who are regressed and show cultural characteristics, the therapists should be aware of the importance of cultural differences. This report discusses recommendations for treating suicidal Asian patients.     

Group therapy for bulimia: Clinical experience and practical recommendations

The authors identify and describe three major types of group therapy for patients with bulimia. Psychodynamic treatment, cognitive-behavioral treatment, and self-help group treatment are techniques with different theoretical bases. Implications for group membership, time frame, leadership, contract, content, and goals are discussed for each type of group treatment. Outcome studies are reviewed, and recommendations are offered for a rational approach to the group treatment of patients with bulimia.Supported in part by a grant from the Gen-Rad Foundation.     

Resolving the latent structure of schizophrenia endophenotypes using expectation-maximization-based finite mixture modeling

Prior research has focused on the latent structure of endophenotypic markers of schizophrenia liability, or schizotypy. The work supports the existence of 2 relatively distinct latent classes and derives largely from the taxometric analysis of psychometric values. The present study used finite mixture modeling as a technique for discerning latent structure and the laboratory-measured endophenotypes of sustained attention deficits and eye-tracking dysfunction as endophenotype indexes. In a large adult community sample (N=311), finite mixture analysis of the sustained attention index d' and 2 eye-tracking indexes (gain and catch-up saccade rate) revealed evidence for 2 latent components. A putative schizotypy class accounted for 27% of the sample. A supplementary maximum covariance taxometric analysis yielded highly consistent results. Subjects in the schizotypy component displayed higher rates of schizotypal personality features and an increased rate of treated schizophrenia in their 1st-degree biological relatives compared with subjects in the other component. Implications of these results are examined in light of major theories of schizophrenia liability, and methodological advantages of finite mixture modeling for psychopathology research, with particular emphasis on genomic issues, are discussed.     

Use of factor mixture modeling to capture Spearman's law of diminishing returns

Spearman's law of diminishing returns (SLODR) posits that at higher levels of general cognitive ability the general factor (g) performs less well in explaining individual differences in cognitive test performance. Research has generally supported SLODR, but previous research has required the a priori division of respondents into separate ability or IQ groups. The present study sought to obviate this limitation through the use of factor mixture modeling to investigate SLODR in the Kaufman Assessment Battery for Children-Second Edition (KABC-II). A second-order confirmatory factor model was modeled as a within-class factor structure. The fit and parameter estimates of several models with varying number of classes and factorial invariance restrictions were compared. Given SLODR, a predictable pattern of findings should emerge when factor mixture modeling is applied. Our results were consistent with these SLODR-based predictions, most notably the g factor variance was less in higher g mean classes. Use of factor mixture modeling was found to provide support for SLODR while improving the model used to investigate SLODR.     

Implementing continuous non-normal skewed distributions in latent growth mixture modeling: An assessment of specification errors and class enumeration

Abstract

Recent advances have allowed for modeling mixture components within latent growth modeling using robust, skewed mixture distributions rather than normal distributions. This feature adds flexibility in handling non-normality in longitudinal data, through manifest or latent variables, by directly modeling skewed or heavy-tailed latent classes rather than assuming a mixture of normal distributions. The aim of this study was to assess through simulation the potential under- or over-extraction of latent classes in a growth mixture model when underlying data follow either normal, skewed-normal, or skewed-t distributions. In order to assess this, we implement skewed-t, skewed-normal, and conventional normal (i.e., not skewed) forms of the growth mixture model. The skewed-t and skewed-normal versions of this model have only recently been implemented, and relatively little is known about their performance. Model comparison, fit, and classification of correctly specified and mis-specified models were assessed through various indices. Findings suggest that the accuracy of model comparison and fit measures are dependent on the type of (mis)specification, as well as the amount of class separation between the latent classes. A secondary simulation exposed computation and accuracy difficulties under some skewed modeling contexts. Implications of findings, recommendations for applied researchers, and future directions are discussed; a motivating example is presented using education data.     

Preadolescent adjudicative competence: methodological considerations and recommendations for practice standards

This article examines developmental and legal issues directed toward a downward age extension of forensic evaluation practice standards for preadolescent defendants whose competence is questioned. Existing research and practice standards were developed for cases involving adolescents and adults, but they lack sufficient application to evaluations of young children because of the ways in which legal parameters affect young children. We review practice implications of the legal role of "immaturity" for adjudicative competence, alterations of Dusky in some juvenile courts, and the role of parens patriae in competence hearings held in juvenile court. We examine competence abilities in a developmental framework. Examining practice standards is timely because adjudicative competence in preadolescent defendants has taken on recent significance. The last decade saw changes in the stringency of delinquency statutes, increased emphasis on adversarial approaches to juvenile proceedings, and a de-emphasis on rehabilitation and parens patriae protections. Statutory changes and increased referrals have heightened inquiry into the meaning of preadolescent adjudicative competence.