Simultaneous estimation of the intermediate correlation matrix for arbitrary marginal densities.

A popular approach to the simulation of multivariate, non-normal data in the social sciences is to define a multivariate normal distribution first, and then alter its lower-dimensional marginals to achieve the shape of the distribution intended by the researchers. A consequence of this process is that the correlation structure is altered, so further methods are needed to specify an intermediate correlation matrix in the multivariate normal distribution step. Most of the techniques available in the literature estimate this intermediate correlation matrix bivariately (i.e., correlation by correlation), risking the possibility of generating a non-positive definite matrix. The present article addresses this issue by offering an algorithm that estimates all elements of the intermediate correlation matrix simultaneously, through stochastic approximation. A small simulation study demonstrates the feasibility of the present method to induce the correlation structure both in simulated and empirical data.

Continuous-Time Modeling of the Bidirectional Relationship Between Incidental Affect and Physical Activity.

BACKGROUND: Previous research suggests that there is a bidirectional relationship between incidental affect (i.e., how people feel in day-to-day life) and physical activity behavior. However, many inconsistencies exist in the body of work due to the lag interval between affect and physical activity measurements. PURPOSE: Using a novel continuous-time analysis paradigm, we examined the temporal specificity underlying the dynamic relationship between positive and negative incidental affective states and moderate-to-vigorous physical activity (MVPA). METHODS: A community sample of adults (n = 126, Mage = 27.71, 51.6% Male) completed a 14-day ambulatory assessment protocol measuring momentary positive and negative incidental affect six times a day while wearing a physical activity monitor (Fitbit). Hierarchical Bayesian continuous-time structural equation modeling was used to elucidate the underlying dynamics of the relationship between incidental affective states and MVPA. RESULTS: Based on the continuous-time cross-effects, positive and negative incidental affect predicted subsequent MVPA. Furthermore, engaging in MVPA predicted subsequent positive and negative incidental affect. Incidental affective states had a greater relative influence on predicting subsequent MVPA compared to the reciprocal relationship. Analysis of the discrete-time coefficients suggests that cross-lagged effects increase as the time interval between measurements increase, peaking at about 8 h between measurement occasions before beginning to dissipate. CONCLUSIONS: The results provide support for a recursive relationship between incidental affective states and MVPA, which is particularly strong at 7-9 hr time intervals. Future research designs should consider these medium-term dynamics, for both theory development and intervention.

Accuracy of mixture item response theory models for identifying sample heterogeneity in patient-reported outcomes: a simulation study.

PURPOSE: Mixture item response theory (MixIRT) models can be used to uncover heterogeneity in responses to items that comprise patient-reported outcome measures (PROMs). This is accomplished by identifying relatively homogenous latent subgroups in heterogeneous populations. Misspecification of the number of latent subgroups may affect model accuracy. This study evaluated the impact of specifying too many latent subgroups on the accuracy of MixIRT models. METHODS: Monte Carlo methods were used to assess MixIRT accuracy. Simulation conditions included number of items and latent classes, class size ratio, sample size, number of non-invariant items, and magnitude of between-class difference in item parameters. Bias and mean square error in item parameters and accuracy of latent class recovery were assessed. RESULTS: When the number of latent classes was correctly specified, the average bias and MSE in model parameters decreased as the number of items and latent classes increased, but specification of too many latent classes resulted in modest decrease (i.e., < 10%) in the accuracy of latent class recovery. CONCLUSION: The accuracy of MixIRT model is largely influenced by the overspecification of the number of latent classes. Appropriate choice of goodness-of-fit measures, study design considerations, and a priori contextual understanding of the degree of sample heterogeneity can guide model selection.

An Examination of Dweck's Psychological Needs Model in Relation to Exercise-Related Well-Being.

This two-part study examined Dweck's psychological needs model in relation to exercise-related well-being and particularly focused on the basic need for optimal predictability and compound needs for identity and meaning. In Part 1 (N = 559), using exploratory factor analysis, scores derived from items assessing optimal predictability (prediction of affect and instrumental utility in exercise) were empirically distinct from scores derived from items assessing competence, relatedness, and autonomy. In Part 2, participants from Part 1 (N = 403) completed measures of exercise-related well-being 4 weeks after baseline assessment. Prediction of affect was the most consistent predictor of subsequent exercise-related well-being. An implication of these findings is that optimal predictability (primarily prediction of affect) represents a unique experience that may be necessary for thriving in the context of exercise. Prediction of affect should be targeted in experimental designs to further understand its relationship with exercise-related well-being.

Scoping review of response shift methods: current reporting practices and recommendations.

BACKGROUND: Response shift (RS) has been defined as a change in the meaning of an individual's self-evaluation of his/her health status and quality of life. Several statistical model- and design-based methods have been developed to test for RS in longitudinal data. We reviewed the uptake of these methods in patient-reported outcomes (PRO) literature. METHODS: CINHAHL, EMBASE, Medline, ProQuest, PsycINFO, and Web of Science were searched to identify English-language articles about RS published until 2016. Data on year and country of publication, PRO measure adopted, RS detection method, type of RS detected, and testing of underlying model assumptions were extracted from the included articles. RESULTS: Of the 1032 articles identified, 101 (9.8%) articles were included in the study. While 54.5 of the articles reported on the Then-test, 30.7% of the articles reported on Oort's or Schmitt's structural equation modeling (SEM) procedure. Newer RS detection methods, such as relative importance analysis and random forest regression, have been used less frequently. Less than 25% reported on testing the assumptions underlying the adopted RS detection method(s). CONCLUSIONS: Despite rapid methodological advancements in RS research, this review highlights the need for further research about RS detection methods for complex longitudinal data and standardized reporting guidelines.

The use of latent variable mixture models to identify invariant items in test construction.

PURPOSE: Patient-reported outcome measures (PROMs) are frequently used in heterogeneous patient populations. PROM scores may lead to biased inferences when sources of heterogeneity (e.g., gender, ethnicity, and social factors) are ignored. Latent variable mixture models (LVMMs) can be used to examine measurement invariance (MI) when sources of heterogeneity in the population are not known a priori. The goal of this article is to discuss the use of LVMMs to identify invariant items within the context of test construction. METHODS: The Draper-Lindely-de Finetti (DLD) framework for the measurement of latent variables provides a theoretical context for the use of LVMMs to identify the most invariant items in test construction. In an expository analysis using 39 items measuring daily activities, LVMMs were conducted to compare 1- and 2-class item response theory models (IRT). If the 2-class model had better fit, item-level logistic regression differential item functioning (DIF) analyses were conducted to identify items that were not invariant. These items were removed and LVMMs and DIF testing repeated until all remaining items showed MI. RESULTS: The 39 items had an essentially unidimensional measurement structure. However, a 1-class IRT model resulted in many statistically significant bivariate residuals, indicating suboptimal fit due to remaining local dependence. A 2-class LVMM had better fit. Through subsequent rounds of LVMMs and DIF testing, nine items were identified as being most invariant. CONCLUSIONS: The DLD framework and the use of LVMMs have significant potential for advancing theoretical developments and research on item selection and the development of PROMs for heterogeneous populations.

The Development and Psychometric Properties of the Multidimensional Assessment of Teamwork in Sport.

The purpose of this research was to develop a questionnaire to assess the multidimensional construct of teamwork in sport and to examine various aspects of validity related to that instrument. A preliminary questionnaire was first created, and feedback on this instrument was then obtained from a sample of team-sport athletes (n = 30) and experts in sport psychology (n = 8). A modified version of the questionnaire was then completed by 607 athletes from 48 teams, and 5 multilevel confirmatory factor analyses were conducted to examine the structural properties of data derived from this instrument. Evidence of adequate model-data fit along with measurement reliability was obtained for each of the 5 models. Taken together, the results from this research provide support for the content, substantive, and structural aspects of construct validity for data derived from the 66-item Multidimensional Assessment of Teamwork in Sport.

Minimal impact of response shift for SF-12 mental and physical health status in homeless and vulnerably housed individuals: an item-level multi-group analysis.

PURPOSE: The purpose of this study was to examine whether homeless or vulnerably housed individuals experienced response shift over a 12-month time period in their self-reported physical and mental health status. METHODS: Data were obtained from the Health and Housing in Transition study, a longitudinal multi-site cohort study in Canada (N = 1190 at baseline). Multi-group confirmatory factor analysis (MG-CFA) and methods for response shift detection at the item level, based on the approach by Oort, were used to test for reconceptualization, reprioritization, and recalibration response shift on the SF-12 in four groups of individuals who were homeless (n = 170), housed (n = 437), or who reported a change in their housing status [from homeless to housed (n = 285) or housed to homeless (n = 73)] over a 12-month time period. Mean and variance adjusted weighted-least squares estimation was used to accommodate the ordinal and binary distributions of the SF-12 items. RESULTS: Using MG-CFA, a strict invariance model showed that the measurement model was equivalent for the four groups at baseline. Although we found small but statistically significant response shift for several measurement model parameters, the impact on the predicted average mental and physical health scores within each of the groups was small. CONCLUSIONS: Response shift does not appear to be a significant concern when using the SF-12 to obtain change scores over a 12-month period in this population.

Is it getting better? An analytical method to test trends in health disparities, with tobacco use among sexual minority vs. heterosexual youth as an example.

BACKGROUND: Previous studies have documented higher health risks for lesbian, gay, and bisexual youth compared to heterosexual youth. However, none has reported whether the sexual orientation-based gaps have widened, narrowed, or remained unchanged over time. The purpose of this study was to develop a way to test differences in trends between sexual minority and heterosexual youth cohorts in population-based studies, with cigarette smoking as an exemplar. METHODS: We analysed the Minnesota Student Survey of 1998-2010, a repeated, cross-sectional census of adolescent health in grades 9 and 12. Our sample was students with recent sexual experience (Ns = 17,376-19,617). Sexual orientation was measured by gender of sexual partners in the past 12 months: students with only opposite-gender partner(s) (OPPOS), students with both male and female partners (BOTH), students with only same-gender partner(s) (SAME). We used logistic regressions to examine trends in prevalence of past-month cigarette smoking from 1998 to 2010, separately for each orientation group. We then applied novel interaction analyses to test whether disparities in smoking prevalence between OPPOS and SAME/BOTH changed over time. RESULTS: Recent smoking rates decreased over time among all orientation groups. BOTH adolescents were more likely than OPPOS adolescents to report past 30-day smoking, but there were no significant differences between SAME adolescents and OPPOS adolescents. Year-by-orientation interactions indicated the gap between BOTH adolescents and OPPOS adolescents widened from 1998 to 2004, then persisted between 2004 and 2010. No significant interaction effects were observed between SAME adolescents and OPPOS adolescents. CONCLUSIONS: All orientation groups had decreasing trends in recent cigarette smoking; however, disparities in smoking rates remain between heterosexual adolescents and bisexual adolescents. These results provide a new method of not just documenting trends within minority groups, but examining whether health equity is improving for them compared to dominant groups.

Variety support and exercise adherence behavior: experimental and mediating effects.

The purpose of this study was to examine the extent to which the provision of variety (i.e., variety support) is related to exercise behavior among physically inactive adults and the extent to which the 'experience of variety' mediates those effects. One hundred and twenty one inactive university students were randomly assigned to follow a high or low variety support exercise program for 6 weeks. Assessments were conducted at baseline, 3- and 6-weeks. Participants in the high variety support condition displayed higher levels of adherence to the exercise program than those in the low variety support condition [F(1, 116) = 5.55, p = .02, η(p)(2) = .05] and the relationship between variety support and adherence was mediated by perceived variety (ß = .16, p < .01). Exercise-related variety support holds potential to be an efficacious method for facilitating greater exercise adherence behaviors of previously inactive people by fostering perceptions of variety.

Psychosocial predictors of changes in adolescent girls' physical activity and dietary behaviors over the course of the Go Girls! group-based mentoring program.

Changes in social cognitions targeted within a group-based mentoring program for adolescent girls were examined as predictors of changes in physical activity (PA) and dietary behavior (in two separate models) over the course of the 7-week program. Data were collected from 310 participants who participated in the program. Multilevel path models were used to assess changes in psychosocial variables predicting changes in behavioral outcomes from pre- to post-program. Analyses revealed that 24.4 and 12.3% of the variance in increases in PA and dietary behavior, respectively, was explained by increases in affective and instrumental attitudes, self-regulatory efficacy (SRE), and intentions. Increases in intentions partially mediated the effects of increases in SRE and affective attitudes on increases in PA behavior. In relation to improvements in dietary behavior, increases in intentions and SRE directly predicted improvements in dietary behavior. These findings suggest potential psychological mechanisms through which a group-based mentoring program may lead to changes in adolescent girls' health-enhancing PA and dietary behaviors.

GrOup based physical Activity for oLder adults (GOAL) randomized controlled trial: study protocol.

BACKGROUND: Physical activity has health benefits across the lifespan, yet only 13 % of Canadian older adults are sufficiently active. Results from a number of observational studies indicate that adults display positive preferences for exercising with others of a similar age and same gender, and that intra-group age- and gender-similarity are associated with elevated exercise adherence. However, research has yet to experimentally examine the extent to which intra-group age- and gender-related similarity affect exercise adherence behaviors. METHODS/DESIGN: The GrOup-based physical Activity for oLder adults (GOAL) trial is a three-arm randomized control trial that will examine the efficacy of two different group-based exercise programs for older adults (informed by the tenets of self-categorization theory) in relation to a standard group-based exercise program. Within this manuscript we outline the design and proposed evaluation of the GOAL trial. The first arm is comprised of exercise groups made up of participants of a similar-age and of the same gender; the second arm consists of groups with similar-aged mixed gender participants; the control arm is comprised of mixed-aged mixed gender participants. We aim to compare the adherence rates of participants across conditions, as well as potential moderation effects and mediating mechanisms. DISCUSSION: Results from this trial will inform intervention designs to improve the exercise adherence behaviors of older adult. At a systems-level, should support be derived for the efficacy of the interventions tested in this trial, changing group composition (i.e., age, gender) represents a feasible program adaptation for physical activity centers. TRIAL REGISTRATION: ClinicalTrials.gov # NCT02023632 . Registered December 13, 2013.

Weighting checklist items and station components on a large-scale OSCE: is it worth the effort?

BACKGROUND: Past research suggests that the use of externally-applied scoring weights may not appreciably impact measurement qualities such as reliability or validity. Nonetheless, some credentialing boards and academic institutions apply differential scoring weights based on expert opinion about the relative importance of individual items or test components of Observed Structured Clinical Examinations (OSCEs). AIMS: To investigate the impact of simplified scoring models that make little to no use of differential weighting on the reliability of scores and decisions on a high stakes OSCE required for medical licensure in Canada. METHOD: We applied four different weighting models of various complexities to data from three administrations of the OSCE. We compared score reliability, pass/fail rates, correlations between the scores and classification decision accuracy and consistency across the models and administrations. RESULTS: Less complex weighting models yielded similar reliability and pass rates as the more complex weighting model. Minimal changes in candidates' pass/fail status were observed and there were strong and statistically significant correlations between the scores for all scoring models and administrations. Classification decision accuracy and consistency were very high and similar across the four scoring models. CONCLUSIONS: Adopting a simplified weighting scheme for this OSCE did not diminish its measurement qualities. Instead of developing complex weighting schemes, experts' time and effort could be better spent on other critical test development and assembly tasks with little to no compromise in the quality of scores and decisions on this high-stakes OSCE.

On Johnson's (2000) Relative Weights Method for Assessing Variable Importance: A Reanalysis.

This article provides a reanalysis of J. W. Johnson's (2000) "relative weights" method for assessing variable importance in multiple regression. The primary conclusion of the reanalysis is that the derivation of the method is theoretically flawed and has no more validity than the discredited method of Green, Carroll, and DeSarbo (1978) on which it is based. By means of 2 examples, supplemented by other results from the literature, it is also shown that the method can result in materially distorted inferences when it is compared with another widely used importance metric, namely, general dominance (Azen & Budescu, 2003; Budescu, 1993). Our primary recommendation is that J. W. Johnson's (2000) relative weights method should no longer be used as a variable importance metric for multiple linear regression. In the final section of the article, 2 additional recommendations are made based on our analysis, examples, and discussion.

Is variety a spice of (an active) life?: perceived variety, exercise behavior, and the mediating role of autonomous motivation.

In this study, we examined whether perceived variety in exercise prospectively predicts unique variance in exercise behavior when examined alongside satisfaction of the three basic psychological needs (for competence, relatedness, and autonomy) embedded within self-determination theory (Ryan & Deci, 2002), through the mediating role of autonomous and controlled motivation. A convenience sample of community adults (N = 363) completed online questionnaires twice over a 6-week period. The results of structural equation modeling showed perceived variety and satisfaction of the needs for competence and relatedness to be unique indirect positive predictors of exercise behavior (through autonomous motivation) 6 weeks later. In addition, satisfaction of the need for autonomy was found to negatively predict controlled motivation. Perceived variety in exercise complemented satisfaction of the needs for competence, relatedness, and autonomy in predicting motivation and (indirectly) exercise behavior, and may act as a salient mechanism in the prediction of autonomous motivation and behavior in exercise settings.

Effects of social belonging and task framing on exercise cognitions and behavior.

The objective of the studies presented in this paper was to examine whether the need to belong can be used to enhance exercise cognitions and behavior. Two studies examined the effectiveness of framing exercise as a means of boosting social skills (versus health benefits) for self-regulatory efficacy, exercise intentions, and (in Study 2) exercise behavior. In Study 1, inactive adults primed to feel a lack of social belonging revealed that this manipulation led to greater self-regulatory efficacy (but not exercise intentions). In Study 2, involving a sample of inactive lonely adults, all participants reported engaging in more exercise; however, those in the social skills condition also reported a greater sense of belonging than those in the health benefits comparison condition. These findings provide an important basis for developing physical activity interventions that might be particularly relevant for people at risk for feeling socially isolated or lonely.

The Effect of Cognitive Fusion on Change in PTSD and Depression Symptom Severity in Veterans Engaged in Group Psychotherapy.

Cognitive fusion occurs when people experience their thoughts as literally true and allow them to dictate behavior. Fusion has been shown to be associated with increased symptoms of post-traumatic stress disorder (PTSD) and depression; however, the association between change in cognitive fusion, PTSD, and depression symptoms has been relatively uninvestigated. Our study aims to examine the associations between PTSD, depression symptoms, and cognitive fusion in Canadian veterans from pre- to post-treatment. Clients (N = 287) completed measures of PTSD symptom severity, depression symptom severity, and cognitive fusion at pre- and post-treatment. Our results supported that pretreatment PTSD and depression symptom severity were found to be negatively associated with changes in pre- to post-treatment cognitive fusion, while pretreatment cognitive fusion was not associated with changes in depression or PTSD symptoms. Furthermore, pretreatment depression symptoms predicted pre- to post-treatment changes in PTSD symptoms. However, pretreatment PTSD symptoms did not predict changes in depression symptoms. These findings highlight the importance of understanding the bidirectional associations between PTSD, depression, and cognitive fusion. Furthermore, our results are indicative of PTSD and depression symptoms playing a role in the change in cognitive fusion (e.g., defusion) and of depression playing a larger role in the maintenance of PTSD symptoms. Theoretical and practical implications are discussed.

Sexual Health and Risk Behaviour among East Asian Adolescents in British Columbia.

Despite the large number of adolescents of East Asian origin in Canada, there is limited research on sexual health among this population. A first step to develop strategies for sexual health promotion for adolescents is to document the prevalence of sexual behaviours. This study thus estimated the prevalence of sexual health and risk behaviours among East Asian adolescents in grades 7 to 12, using the province-wide, school-based 2008 British Columbia Adolescent Health Survey (unweighted N = 4,311). Less than 10% of East Asian adolescents have ever had sexual intercourse. However, most of these sexually active adolescents have engaged in risky sexual behaviours, including multiple sexual partners and non-condom use at last intercourse. In particular, nearly half of sexually active girls reported not using a condom at last intercourse. Compared to immigrant students whose primary language at home was not English, immigrant and Canadian-born students speaking English at home were more likely to experience sexual intercourse. Among students who have never had sexual intercourse, two most common reasons for sexual abstinence were not feeling ready and waiting to meet the right person. Findings suggest the need for sexual health interventions tailored to gender and sociocultural contexts in which adolescents live.