Many nonnormalities, one simulation: Do different data generation algorithms affect study results?

Monte Carlo simulation studies are among the primary scientific outputs contributed by methodologists, guiding application of various statistical tools in practice. Although methodological researchers routinely extend simulation study findings through follow-up work, few studies are ever replicated. Simulation studies are susceptible to factors that can contribute to replicability failures, however. This paper sought to conduct a meta-scientific study by replicating one highly cited simulation study (Curran et al., Psychological Methods, 1, 16-29, 1996) that investigated the robustness of normal theory maximum likelihood (ML)-based chi-square fit statistics under multivariate nonnormality. We further examined the generalizability of the original study findings across different nonnormal data generation algorithms. Our replication results were generally consistent with original findings, but we discerned several differences. Our generalizability results were more mixed. Only two results observed under the original data generation algorithm held completely across other algorithms examined. One of the most striking findings we observed was that results associated with the independent generator (IG) data generation algorithm vastly differed from other procedures examined and suggested that ML was robust to nonnormality for the particular factor model used in the simulation. Findings point to the reality that extant methodological recommendations may not be universally valid in contexts where multiple data generation algorithms exist for a given data characteristic. We recommend that researchers consider multiple approaches to generating a specific data or model characteristic (when more than one is available) to optimize the generalizability of simulation results.

One step at a time: A statistical approach for distinguishing mediators, confounders, and colliders using direction dependence analysis.

In observational data, understanding the causal link when estimating the causal effect of an independent variable (x) on a dependent variable (y) often requires researchers to identify the role of a third variable in the x → y relationship. Mediation, confounding, and colliding are three key third-variable effects that yield different theoretical and methodological implications for drawing causal conclusions. Commonly used covariance-based statistical methods, such as linear regression and structural equation modeling, cannot distinguish these effects in practice, however. In this study, we introduce a statistical approach for distinguishing mediators, confounders, colliders, and potential M-bias structures that uses higher-order moment information from the data. We propose a two-step procedure that uses the Hilbert-Schmidt independence criterion within the direction dependence analysis framework. Results from Monte Carlo simulations show that our proposed approach accurately recovers the true data-generating process of the third variable. We provide an empirical example to demonstrate the application of our proposed approach in psychological research. Finally, we discuss implications and future directions of our work. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Design, analysis, and interpretation of treatment response heterogeneity in personalized nutrition and obesity treatment research.

It is increasingly assumed that there is no one-size-fits-all approach to dietary recommendations for the management and treatment of chronic diseases such as obesity. This phenomenon that not all individuals respond uniformly to a given treatment has become an area of research interest given the rise of personalized and precision medicine. To conduct, interpret, and disseminate this research rigorously and with scientific accuracy, however, requires an understanding of treatment response heterogeneity. Here, we define treatment response heterogeneity as it relates to clinical trials, provide statistical guidance for measuring treatment response heterogeneity, and highlight study designs that can quantify treatment response heterogeneity in nutrition and obesity research. Our goal is to educate nutrition and obesity researchers in how to correctly identify and consider treatment response heterogeneity when analyzing data and interpreting results, leading to rigorous and accurate advancements in the field of personalized medicine.

Cataract Surgery in the Medicare Merit-Based Incentive Payment System: Episode-Based Cost Measure Development and Evaluation.

Objective: To characterize the development and performance of a cataract surgery episode-based cost measure for the Medicare Quality Payment Program. Design: Claims-based analysis. Participants: Medicare clinicians with cataract surgery claims between June 1, 2016, and May 31, 2017. Methods: We limited the analysis to claims with procedure code 66984 (routine cataract surgery), excluding cases with relevant ocular comorbidities. We divided episodes into subgroups by surgery location (Ambulatory Surgery Center [ASC] or Hospital Outpatient Department [HOPD]) and laterality (bilateral when surgeries were within 30 days apart). For the episode-based cost measure, we calculated costs occurring between 60 days before surgery and 90 days after surgery, limited to services identified by an expert committee as related to cataract surgery and under the influence of the cataract surgeon. We attributed costs to the clinician submitting the cataract surgery claim, categorized costs into clinical themes, and calculated episode cost distribution, reliability in detecting clinician-dependent cost variation, and costs with versus without complications. We compared episode-based cost scores with hypothetical "nonselective" cost scores (total Medicare beneficiary costs between 60 days before surgery and 90 days after surgery). Main Outcome Measures: Episode costs with and without complications, clinician-dependent variation (proportion of total cost variance), and proportion of costs from cataract surgery-related clinical themes. Results: We identified 583 356 cataract surgery episodes attributed to 10 790 clinicians and 8189 with ≥ 10 episodes during the measurement period. Most surgeries were performed in an ASC (71%) and unilateral (66%). The mean episode cost was $2876. The HOPD surgeries had higher costs; geography and episodes per clinician did not substantially affect costs. The proportion of cost variation from clinician-dependent factors was higher in episode-based compared with nonselective cost measures (94% vs. 39%), and cataract surgery-related clinical themes represented a higher proportion of total costs for episode-based measures. Episodes with complications had higher costs than episodes without complications ($3738 vs. $2276). Conclusions: The cataract surgery episode-based cost measure performs better than a comparable nonselective measure based on cost distribution, clinician-dependent variance, association with cataract surgery-related clinical themes, and quality alignment (higher costs in episodes with complications). Cost measure maintenance and refinement will be important to maintain clinical validity and reliability. Financial Disclosures: Proprietary or commercial disclosure may be found after the references.

An overview of the Together Everyone Achieves More Physical Activity (TEAM-PA) trial to increase physical activity among African American women.

BACKGROUND: The Together Everyone Achieves More Physical Activity (TEAM-PA) trial is a randomized controlled trial testing the efficacy of a group-based intervention for increasing physical activity (PA) among insufficiently active African American women. DESIGN: The TEAM-PA trial uses a group cohort design, is implemented at community sites, and will involve 360 African American women. The trial compares a 10-week group-based intervention vs. a standard group-delivered PA comparison program. Measures include minutes of total PA/day using 7-day accelerometer estimates (primary outcome), and body mass index, blood pressure, waist circumference, walking speed, sedentary behavior, light physical activity, and the percentage achieving ≥150 min of moderate to vigorous PA/week (secondary outcomes) at baseline, post-intervention, and 6-months post-intervention. INTERVENTION: The intervention integrates elements from Social Cognitive Theory, Self-Determination Theory, Group Dynamics Theory, and a focus on collectivism to evaluate different components of social affiliation (relatedness, reciprocal support, group cohesion, and collective efficacy). The intervention integrates shared goal-setting via Fitbits, group-based problem-solving, peer-to-peer positive communication, friendly competition, and cultural topics related to collectivism. Compared to the standard group-delivered PA program, participants in the intervention are expected to show greater improvements from baseline to post- and 6-month follow-up on minutes of total PA/day and secondary outcomes. Social affiliation variables (vs. individual-level factors) will be evaluated as mediators of the treatment effect. IMPLICATIONS: The results of the TEAM-PA trial will determine the efficacy of the intervention and identify which aspects of social affiliation are most strongly related to increased PA among African American women. TRIAL REGISTRATION: This study was registered on Clinicaltrials.gov (# NCT05519696) in August 2022 prior to initial participant enrollment.

Low normal FMR1 genotype in older adult women: Psychological well-being and motor function.

The FMR1 gene plays a key role in adult neurogenesis and neuroplasticity, and thus may contribute to age-related health in the population. The current study focused on the "low normal" FMR1 genotype, defined by lower-than-typical numbers of FMR1 CGG repeats (<26), as a potential genetic determinant of age-related health. We characterized the effect of the low normal FMR1 genotype on psychological well-being and motor function in a racially diverse non-clinical sample of older adult women. Women with low CGG repeats were distinguished from those with CGGs falling within the mid-high end of the normal range by reduced performance on multimodal assessments of motor function and psychological well-being, with large effect sizes. Robust continuous associations were also detected between lower CGG repeat length and reduced psychological well-being, balance, and dexterity. Findings suggest that FMR1 may represent an important mediator of individual differences in age-related health; larger epidemiological studies are needed. Given that approximately 23-35% of females carry the low normal genotype, efforts to understand its clinical effects have relevance a broad swath of the aging population.

The role of frailty in the association between depression and fall risk among older adults.

OBJECTIVES: Although there is a recognized association between depression and greater fall risk among older adults, the mechanisms explaining this association are unclear. This study evaluated the role of frailty, a common geriatric syndrome, in determining greater risk of falls among older adults with depression. METHOD: We used longitudinal data from three biennial waves of the Health and Retirement Study (HRS; 2010-2014). The sample included community-dwelling survey respondents age ≥ 65 who participated in objective physiological measures. Major Depression (MD) was measured using Composite International Diagnostic Interview for depression short form. Frailty was measured using criteria outlined in the frailty phenotype model. Causal mediation analysis was used to differentiate the direct effect of depression and indirect effect mediated by frailty on falls, fall injuries, and multiple falls. RESULTS: Major depression was associated with significantly greater odds of experiencing a fall (OR: 1.91; 95% CI: 1.31, 2.77), fall injury (OR: 1.86; 95% CI: 1.17, 2.95), and multiple falls (OR: 2.26; 95% CI: 1.52, 3.37) over a two-year period. Frailty was a significant mediator of the effects of depression on falls and multiple falls, accounting for approximately 18.9% and 21.3% of the total effects, respectively. We found no evidence of depression-frailty interaction. Sensitivity analyses showed that results were robust to unmeasured confounding and alternative operationalizations of depression. CONCLUSION: Frailty explains a significant proportion of increased likelihood of falls among older adults with depression. Treatment and management of frailty symptoms may be an important components of fall prevention among older adults with depression.

Future Orientation Among Children Affected by Parental HIV in China: An Exploratory Analysis of Complex Interactions.

We utilized an exploratory analytic approach to examine predictors of children's future beliefs, an internal asset associated with resilience among children affected by HIV, with emphasis on complex interactions among multisystem factors. Children (N = 1221) affected by parental HIV in China reported on psychosocial functioning, as well as internal, familial, and community resilience assets. Exploratory data analysis was conducted using a binary segmentation program. Six binary splits on predictors accounted for 22.78% of the variance in future expectation, suggesting interactions between children's perceived control of their future, loneliness, caregiver trust, and social support. Four binary splits accounted for 23.15% of the variance in future orientation, suggesting multiway interactions between control of the future, loneliness, social support, and perceived stigma. Findings suggest combinations of resilience factors are associated with children's positive future beliefs. Implications for screening, prevention, and intervention among Chinese children affected by parental HIV are discussed.

Family history of FXTAS is associated with age-related cognitive-linguistic decline among mothers with the FMR1 premutation.

BACKGROUND: Women who carry a premutation allele of the FMR1 gene are at increased vulnerability to an array of age-related symptoms and disorders, including age-related decline in select cognitive skills. However, the risk factors for age-related decline are poorly understood, including the potential role of family history and genetic factors. In other forms of pathological aging, early decline in syntactic complexity is observed and predicts the later onset of neurodegenerative disease. To shed light on the earliest signs of degeneration, the present study characterized longitudinal changes in the syntactic complexity of women with the FMR1 premutation across midlife, and associations with family history of fragile X-associated tremor/ataxia syndrome (FXTAS) and CGG repeat length. METHODS: Forty-five women with the FMR1 premutation aged 35-64 years at study entry participated in 1-5 longitudinal assessments spaced approximately a year apart (130 observations total). All participants were mothers of children with confirmed fragile X syndrome. Language samples were analyzed for syntactic complexity and participants provided information on family history of FXTAS. CGG repeat length was determined via molecular genetic testing. RESULTS: Hierarchical linear models indicated that women who reported a family history of FXTAS exhibited faster age-related decline in syntactic complexity than those without a family history, with that difference emerging as the women reached their mid-50 s. CGG repeat length was not a significant predictor of age-related change. CONCLUSIONS: Results suggest that women with the FMR1 premutation who have a family history of FXTAS may be at increased risk for neurodegenerative disease, as indicated by age-related loss of syntactic complexity. Thus, family history of FXTAS may represent a personalized risk factor for age-related disease. Follow-up study is needed to determine whether syntactic decline is an early indicator of FXTAS specifically, as opposed to being a more general age-related cognitive decline associated with the FMR1 premutation.

An overview of the Connect through PLAY trial to increase physical activity in underserved adolescents.

BACKGROUND: The Connect through Positive Leisure Activities for Youth (Connect through PLAY) trial is a prospective, randomized controlled trial implemented within pre-existing afterschool programs (ASPs) comparing a staff-based social development physical activity (PA) program to a health curriculum active control. The efficacy trial aims to improve staff capacity for implementing effective physical activity (PA) programming within ASPs serving underserved youth (minority, low-income) through enhancing the influence of ASP staff as key change agents and addressing the social development needs of adolescents. DESIGN AND SETTING: The 5-year cluster randomized trial will involve 30 ASPs that are randomized to either the Connect through PLAY intervention or the active health curriculum control. INTERVENTION: The Connect through PLAY intervention employs a novel theoretical framework that targets three key social mechanisms for increased and sustained PA of staff and youth including youth-peer connections/friendships, group belonging, and staff-youth connections. All components of the intervention are designed to improve staff capacity for facilitating a PA context that supports these social mechanisms and increases the influence of ASP staff as positive PA role models and agents of change. Compared to control sites, ASPs receiving Connect through PLAY are expected to show greater improvements from baseline to post- and 6-month follow-up on youth PA, staff PA, and social mechanisms. IMPLICATIONS: The results of the Connect through PLAY trial will demonstrate the efficacy of the intervention and will assist in developing a model of training, motivating, and empowering ASP staff to address social mechanisms that promote youth PA.

A Guideline for Reporting Mediation Analyses of Randomized Trials and Observational Studies: The AGReMA Statement.

Importance: Mediation analyses of randomized trials and observational studies can generate evidence about the mechanisms by which interventions and exposures may influence health outcomes. Publications of mediation analyses are increasing, but the quality of their reporting is suboptimal. Objective: To develop international, consensus-based guidance for the reporting of mediation analyses of randomized trials and observational studies (A Guideline for Reporting Mediation Analyses; AGReMA). Design, Setting, and Participants: The AGReMA statement was developed using the Enhancing Quality and Transparency of Health Research (EQUATOR) methodological framework for developing reporting guidelines. The guideline development process included (1) an overview of systematic reviews to assess the need for a reporting guideline; (2) review of systematic reviews of relevant evidence on reporting mediation analyses; (3) conducting a Delphi survey with panel members that included methodologists, statisticians, clinical trialists, epidemiologists, psychologists, applied clinical researchers, clinicians, implementation scientists, evidence synthesis experts, representatives from the EQUATOR Network, and journal editors (n = 19; June-November 2019); (4) having a consensus meeting (n = 15; April 28-29, 2020); and (5) conducting a 4-week external review and pilot test that included methodologists and potential users of AGReMA (n = 21; November 2020). Results: A previously reported overview of 54 systematic reviews of mediation studies demonstrated the need for a reporting guideline. Thirty-three potential reporting items were identified from 3 systematic reviews of mediation studies. Over 3 rounds, the Delphi panelists ranked the importance of these items, provided 60 qualitative comments for item refinement and prioritization, and suggested new items for consideration. All items were reviewed during a 2-day consensus meeting and participants agreed on a 25-item AGReMA statement for studies in which mediation analyses are the primary focus and a 9-item short-form AGReMA statement for studies in which mediation analyses are a secondary focus. These checklists were externally reviewed and pilot tested by 21 expert methodologists and potential users, which led to minor adjustments and consolidation of the checklists. Conclusions and Relevance: The AGReMA statement provides recommendations for reporting primary and secondary mediation analyses of randomized trials and observational studies. Improved reporting of studies that use mediation analyses could facilitate peer review and help produce publications that are complete, accurate, transparent, and reproducible.

Response Inhibition Deficits in Women with the FMR1 Premutation are Associated with Age and Fall Risk.

One in 113-178 females worldwide carry a premutation allele on the FMR1 gene. The FMR1 premutation is linked to neurocognitive and neuromotor impairments, although the phenotype is not fully understood, particularly with respect to age effects. This study sought to define oculomotor response inhibition skills in women with the FMR1 premutation and their association with age and fall risk. We employed an antisaccade eye-tracking paradigm to index oculomotor inhibition skills in 35 women with the FMR1 premutation and 28 control women. The FMR1 premutation group exhibited longer antisaccade latency and reduced accuracy relative to controls, indicating deficient response inhibition skills. Longer response latency was associated with older age in the FMR1 premutation and was also predictive of fall risk. Findings highlight the utility of the antisaccade paradigm for detecting early signs of age-related executive decline in the FMR1 premutation, which is related to fall risk. Findings support the need for clinical prevention efforts to decrease and delay the trajectory of age-related executive decline in women with the FMR1 premutation during midlife.

Antidepressant Use Partially Mediates the Association Between Depression and Risk of Falls and Fall Injuries Among Older Adults.

BACKGROUND: The association between depression and fall risk in older adults is recognized, yet the mechanisms underlying this association are unclear. This study estimated the mediating role of antidepressant use in the association between depression and falls and fall injuries. METHODS: Longitudinal data from the Health and Retirement Study (2004-2006) were linked with medication data from the Prescription Drug Study (2005). The sample included community-dwelling adults aged ≥65 with data on depression and medication use (n = 3565). Depression was measured using 2 independent survey tools: Composite International Diagnostic Interview for depression short form and an 8-item version of the Center for Epidemiological Studies-Depression scale. We used causal mediation analysis to estimate and compare the direct and indirect (mediated by antidepressant use) effects of depression on falls and fall injuries. RESULTS: Individuals with major depressive disorder were significantly more likely to experience a fall (OR: 1.92; 95% CI: 1.41, 2.62) and a fall injury (OR: 1.67; 95% CI: 1.09, 2.55) over 2 years. Indirect effect estimates showed that antidepressant medication use accounted for approximately 19% and 18% of the association between major depressive disorder and falls and fall injuries, respectively. Results were similar when using an alternative depression measure and when considering only selective serotonin reuptake inhibitor antidepressants. CONCLUSIONS: Antidepressant use explains a significant proportion, but not a majority, of the association between depression and greater fall risk. Treatment benefits of antidepressants should be considered with, and may outweigh, concerns about increased risk of falls associated with antidepressant use.

Fitting Ordinal Factor Analysis Models With Missing Data: A Comparison Between Pairwise Deletion and Multiple Imputation.

This study compares two missing data procedures in the context of ordinal factor analysis models: pairwise deletion (PD; the default setting in Mplus) and multiple imputation (MI). We examine which procedure demonstrates parameter estimates and model fit indices closer to those of complete data. The performance of PD and MI are compared under a wide range of conditions, including number of response categories, sample size, percent of missingness, and degree of model misfit. Results indicate that both PD and MI yield parameter estimates similar to those from analysis of complete data under conditions where the data are missing completely at random (MCAR). When the data are missing at random (MAR), PD parameter estimates are shown to be severely biased across parameter combinations in the study. When the percentage of missingness is less than 50%, MI yields parameter estimates that are similar to results from complete data. However, the fit indices (i.e., χ2, RMSEA, and WRMR) yield estimates that suggested a worse fit than results observed in complete data. We recommend that applied researchers use MI when fitting ordinal factor models with missing data. We further recommend interpreting model fit based on the TLI and CFI incremental fit indices.

Pharmacokinetics and Pharmacodynamics of Immediate- and Modified-Release Mycophenolic Acid Preparations in Healthy Beagle Dogs.

Background: Mycophenolic acid (MPA) is a broad-acting immunomodulating agent that may be therapeutically beneficial for the treatment of immune-mediated diseases in canine patients. Objectives: To determine the suppressive effects of MPA on T-cell proliferation, and to assess the feasibility of a canine-specific q24 h modified-release MPA formulation (OKV-1001b). Animals: Fifteen healthy purpose-bred male beagle dogs. Methods: Two nearly identical open-label fifteen-day studies were conducted in which dogs were randomized to receive mycophenolate mofetil (MMF; 10 mg/kg q12h), or two doses of OKV-1001b (270 mg and 180 mg; q24h). Serial pharmacokinetic (PK) and pharmacodynamic (PD) samples were collected on Days 1, 8, and 15. MPA plasma concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), while an ex vivo T-cell proliferation assay assessed PD effects. Dogs were continuously monitored for evidence of side effects and gastrointestinal tolerability. Results: MPA induced inhibition of T-cell proliferation was observed following administration of all MPA preparations in a clear concentration-dependent manner. The PK/PD relationship was maintained across all days and time-points. Data generated herein suggest that MPA plasma concentrations above 600 ng/mL achieve at least 50% inhibition of T-cell proliferation. Conclusions and Clinical Importance: MPA holds therapeutic potential for treating dogs with immune-mediated disease, but clinical trials will be necessary to determine its safety and efficacy in naturally occurring disease. Likewise, q24h oral modified release MPA preparations that maintain MPA plasma concentrations between 600 and 1,000 ng/mL are warranted for further studies in client-owned dogs.

Estimating causal effects in linear regression models with observational data: The instrumental variables regression model.

Instrumental variable methods are an underutilized tool to enhance causal inference in psychology. By way of incorporating predictors of the predictors (called "instruments" in the econometrics literature) into the model, instrumental variable regression (IVR) is able to draw causal inferences of a predictor on an outcome. We show that by regressing the outcome y on the predictors x and the predictors on the instruments, and modeling correlated disturbance terms between the predictor and outcome, causal inferences can be drawn on y on x if the IVR model cannot be rejected in a structural equation framework. We provide a tutorial on how to apply this model using ML estimation as implemented in structural equation modeling (SEM) software. We additionally provide code to identify instruments given a theoretical model, to select the best subset of instruments when more than necessary are available, and we guide researchers on how to apply this model using SEM. Finally, we demonstrate how the IVR model can be estimated using a number of estimators developed in econometrics (e.g., 2-stage least squares regression) and point out that the latter is simply a multistage SEM estimator of the IVR model. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

An Empirical Mediation Analysis of Mechanisms Underlying HIV-1-Associated Neurocognitive Disorders.

HIV-1-associated neurocognitive disorders (HAND), characterized by alterations in the core components of cognitive function and age-related disease progression, persist in the post-cART era. However, the neurobehavioral mechanisms that mediate alterations in the core components of cognitive function and the progression of neurocognitive impairments have yet to be systematically evaluated. To address this knowledge gap, statistical mediation analysis was assessed, providing a critical opportunity to empirically evaluate putative neurobehavioral mechanisms underlying HAND. Neurocognitive assessments, conducted in HIV-1 transgenic (Tg) and control animals across the functional lifespan (i.e., Postnatal Day (PD) 30 to PD 600), tapped multiple cognitive domains including preattentive processes, learning, sustained attention, and long-term episodic memory. Three longitudinal mediation models were utilized to assess whether deficits in preattentive processes mediate alterations in learning, sustained attention and/or long-term episodic memory over time. Preattentive processes partially mediated the relationship between genotype and learning, genotype and sustained attention, and genotype and long-term episodic memory across the functional lifespan, explaining between 44% and 58% of the HIV-1 transgene effect. Understanding the neurobehavioral mechanisms mediating alterations in HAND may provide key targets for the development of a diagnostic biomarker, novel therapeutics, and cure/restoration strategies.

Social Avoidance Emerges in Infancy and Persists into Adulthood in Fragile X Syndrome.

Fragile X syndrome (FXS) is characterized by both social approach and social avoidance. However, the age of emergence and developmental trajectory of social avoidance has not been examined. This study investigates the longitudinal developmental trajectory and dynamic nature of social avoidance in males with FXS from infancy through young adulthood (n = 191). Multiple facets of social avoidance were collected using the Social Avoidance Scale (Roberts et al. 2007, 2009). Overall, 81% of males with FXS displayed social avoidance, which emerged during infancy, increased in severity across childhood, and stabilized through adolescence and early adulthood. An exaggerated "warm up" effect was also observed in FXS. This study delineates the complex profile of social avoidance, a common and impairing behavioral feature of FXS.

Evaluating a Method to Estimate Mediation Effects With Discrete-Time Survival Outcomes.

The utility of evaluating mediation effects spans across research domains. The model facilitates investigation of underlying mechanisms of event timing and, as such, has the potential to help strengthen etiological research and inform intervention work that incorporates the evaluation of mediating variables. In order for the analyses to be maximally useful however, it is critical to employ methodology appropriate for the data under investigation. The purpose of this paper is to evaluate a regression-based approach to estimating mediation effects with discrete-time survival outcomes. We empirically evaluate the performance of the discrete-time survival mediation model in a statistical simulation study, and demonstrate that results are functionally equivalent to estimates garnered from a potential-outcomes framework. Simulation results indicate that parameter estimates of mediation in the model were statistically accurate and precise across the range of examined conditions. Type 1 error rates were also tolerable in the conditions studied. Adequate power to detect effects in the model, with binary X and continuous M variables, required effect sizes of the mediation paths to be medium or large. Possible extensions of the model are also considered.

Assessing Acceptability of the Term: "Psychopathology" Among Youth Aged 18-25.

A prevailing model for mental health care for youth and families is to provide services within a "psychopathology" focused framework. This approach can compound problems for youth by imparting negative labels on them, and may be associated with iatrogenic impacts of interventions (e.g., stigmatization, lowered self-efficacy, dependency). This study assessed perceptions of the term "psychopathology" among 486 youth aged 18-25, with 39% of these youth receiving prior mental health services. Results indicated statistically significant differences in perception of the term, with youth who had received mental health services perceiving it more negatively than youth who had not. Findings suggest receipt of mental health services among young people may sensitize them to negative aspects of the term psychopathology, indicating the need for caution in using this term and other terms that may have negative impacts on mental health service use among youth.