Bootstrap Confidence Intervals Research Articles

Stress–strength reliability estimation of s-out-of-k multicomponent systems based on copula function for dependent strength elements under progressively censored sample

The main objective of this research is to determine the reliability of multicomponent stress–strength under progressive Type II censoring. The model comprises k independent strength components, and each component has two elements that are statistically dependent and exposed to the same random stress. To assess the correlation between their elements, we are utilizing the Gumbel copula and assuming that its parameter is unknown. The system is deemed operational only if at least certain number of strength variables s ( 1 ≤ s ≤ k ) surpass the random stress. We are using the Chen distribution to model the stress and strength variables, with varying shape parameters. Different methods are employed to estimate the unknown parameters, including maximum likelihood, maximum product of spacings, Cramér–von-Mises, and bootstrap confidence intervals. The effectiveness of these estimation techniques is evaluated through Monte Carlo simulation, and a real data set is analyzed to illustrate our procedures.

A Tidy Framework and Infrastructure to Systematically Assemble Spatio-temporal Indexes from Multivariate Data

Indexes are useful for summarizing multivariate information into single metrics for monitoring, communicating, and decision-making. While most work has focused on defining new indexes for specific purposes, more attention needs to be directed toward making it possible to understand index behavior in different data conditions, and to determine how their structure affects their values and the variability therein. Here we discuss a modular data pipeline recommendation to assemble indexes. It is universally applicable to index computation and allows investigation of index behavior as part of the development procedure. One can compute indexes with different parameter choices, adjust steps in the index definition by adding, removing, and swapping them to experiment with various index designs, calculate uncertainty measures, and assess indexes’ robustness. The article presents three examples to illustrate the usage of the pipeline framework: comparison of two different indexes designed to monitor the spatio-temporal distribution of drought in Queensland, Australia; the effect of dimension reduction choices on the Global Gender Gap Index (GGGI) on countries’ ranking; and how to calculate bootstrap confidence intervals for the Standardized Precipitation Index (SPI). The methods are supported by a new R package, called tidyindex. Supplemental materials for the article are available online.

115 Confidence intervals for validation statistics with data truncation in genomic prediction

Abstract Validation by data truncation is a common practice in genetic evaluations because of the interest in predicting the genetic merit of a set of young selection candidates. Two of the most used validation methods in genetic evaluations are predictivity (correlation between pre-adjusted phenotypes and EBV) divided by the square root of the heritability) and the linear regression (LR) method. Both methods compare predictions with the whole and partial datasets obtained by removing the information related to a set of validation individuals. Confidence intervals (CI) for predictivity and the LR method can be obtained by k-fold validation or bootstrapping. Analytical or frequentist CI are unavailable for predictivity and the LR method and would be beneficial to avoid running several validations. The analytical CI can also help test the quality of bootstrap intervals. This study aimed to derive analytical CI for predictivity, and statistics included in the LR method (bias, dispersion, ratio of accuracies, and reliability). The CI for the bias, dispersion, and reliability depends on the (co)variances of the EBV across the individuals in the validation set. The CI for the ratio of accuracies and predictivity were obtained through the Fisher transformation. We showed the adequacy of the analytical CI using simulation. The analytical CI were closer to the simulated ones. Bootstrap CI tend to be narrower than the simulated ones. Estimating the sampling variation of predictivity and the statistics in the LR method without replication or bootstrap is possible for any dataset with the method proposed in this study. All the formulas derived in this study were implemented in a new program belonging to the BLUPF90 suite called Validationf90.

B - 72 Cognitive Regulation as a Predictor of Parenting Distress

Abstract Objective To determine the relationship between adverse childhood events (ACE), executive function, and parenting. Method Pregnant individuals with and without a history of substance use were recruited to participate in a longitudinal study on perinatal reward processing and parenting. Data were collected from 111 pregnant participants, from which 43 contributed data at six months postpartum. Childhood trauma was collected via the ACE scale, and executive function (EF) challenges were measured using the Metacognition Index of the Behavior Ratings Inventory of Executive Functions for Adults (BRIEF-A). Parenting stress was assessed using the Parenting Stress Inventory, Short Form. The parental distress (PD) and parent perception of their child’s dysregulation (DC) scales were calculated from the PSI at the 6-month timepoint (N = 43 dyads, mean infant age = 27.14 (2.45) weeks.). A structural equation modeling approach was utilized to assess the direct and indirect effects of ACEs and EF challenges on PD and DC. A path mediation model was used. All models were estimated using the R Statistical Software Lavaan package. Bootstrapped confidence intervals were calculated for all paths. Missing data were handled using full information maximum likelihood. Results We found a significant indirect effect of ACEs on DC through metacognition (β = 0.1, 95% CI [0.01, 0.18], p = 0.026) and a significant indirect effect of ACEs on PD through metacognition (β = 0.13, 95% CI [0.02, 0.23], p = 0.019). There were no significant direct effects of ACE on PD or DC. Conclusion This analysis supports the hypothesis that EF, specifically cognitive regulation, impacts PS in the context of a history of ACE.

Confidence Intervals for the Mean and Difference of Means of Birnbaum-Saunders Distributions with Application to Wind Speed Data

This paper proposes the confidence intervals for the mean and difference of means of Birnbaum-Saunders (BirSau) distributions based on the Bootstrap confidence interval (BCI), Percentile bootstrap confidence interval (PBCI), Generalized confidence interval (GCI), Bayesian credible interval (BayCrI) and the highest posterior density (HPD). The simulation study used R statistical software to evaluate the coverage probabilities and average lengths. The concerning results of the mean suggest that HPD is the recommended method for constructing confidence intervals in the BirSau distributions, except for small sample sizes where the GCI method proves more efficient. For the difference of means, PBCI emerges as the preferred way to construct confidence intervals, except in some cases where small sample sizes with the HPD method are more efficient. Moreover, the average lengths of these proposed confidence intervals decreased as both sample size and shape parameters increased. To illustrate the effectiveness of the suggested confidence intervals, we applied them to wind speed datasets collected in Ayutthaya and Ratchaburi provinces, Thailand.

Process Capability Index for Simple Linear Profile in the Presence of Within- and Between-Profile Autocorrelation

In many situations, the quality of a process or product can be characterized by a functional relationship or profile. It is well-known that the independence assumptions of the error terms within or between profiles are not always valid and could be violated due to within or between profile autocorrelation. Since most of the process capability indices (PCIs) have been developed for simple linear profiles (SLPs) without considering autocorrelation, this paper provides some novel methods to analyze the capability of SLP under each of the two different autocorrelation effects separately, as well as the case where both autocorrelation effects are present. We assume that the first-order autoregressive AR(1) model explains the within- and between-profile autocorrelation in error terms. To evaluate the process capability, a new functional index called is introduced for SLP with independent errors, and then it is modified to include the three possible cases of within, between, and simultaneous autocorrelation. The simulation results demonstrate that the proposed schemes outperform existing schemes regarding bias and mean square error (MSE) criteria. Moreover, bootstrap confidence intervals for the proposed index are obtained. Finally, an illustrative example in the chemical industry is used to demonstrate the applicability of the proposed method.

Purpose in life among haemodialysis caregivers: Links with adaptive coping, caregiver burden, and psychological distress.

Research has evidenced that purpose in life helps to minimise the strains of providing informal care to a significant other, but little is known about whether this psychological resource influences the paths from stressors to the health outcomes of family caregiving and through which mechanisms it can exert this protective effect. This study aimed to explore the moderating role of purpose in life on the (mediated through adaptive coping) relationship between caregiver burden and psychological distress in haemodialysis caregivers. A cross-sectional study was conducted with a convenience sample of family caregivers (n=173; M=55.9, SD=15.6years old) of adults undergoing haemodialysis. A moderated-mediation model was computed to explore the interaction effects of purpose in life on the path between burden and distress, having adaptive coping behaviours as parallel mediators. Results showed that purpose in life had a buffering effect on the mediated (through acceptance coping) relationship between burden and distress (index of partial moderated-mediation: bsimple=-0.029, 95% bootstrap confidence interval (CI) [-0.070, -0.002]), and that this conditional effect was lowest at high levels of the moderator (at +1SD: bsimple=0.038, SE=0.026, 95% bootstrap CI [0.001, 0.098]). Use of emotional support (F(1,159)=4.395, p=0.038) and positive reframing (F(1,159)=5.648, p=0.019) also mediated this path. This study expands knowledge about the modifiable internal resources through which purpose in life can help promote psychosocial adjustment to the haemodialysis caregiving process. Mental health promotion initiatives aimed at this population need to consider combining different intervention approaches to foster purpose in life and train adaptive (and flexible) coping skills.

How Debt and Attainment Relate through the GPA of Non-White College Students

This study investigated the effects of U.S. student loans on attainment via the GPA of non-white undergraduates. The data for the study were drawn from the 2012/2017 Beginning Postsecondary Students Longitudinal Study (BPS: 12/17), encompassing a nationally representative sample of 1500 African American, Hispanic, Asian, multiracial, and other non-white students. The results, based on regression models and the bootstrapped confidence interval (BCI) method, indicated that student loans were associated with GPA, and both student loans and GPA were associated with attainment. Notably, the indirect effect of loan status on attainment was negative, whereas the indirect effect of high debt on attainment was positive. These findings highlight the indirect relationship between student loans and attainment and suggest that high debt has the potential to offset the negative effect of loan status on academic outcomes. The implications of these findings for higher education practice and policy debates are critical, particularly in the context of addressing non-white students’ financial needs and enhancing their academic outcomes.

Establishing a standardised approach for the measurement of neonatal noxious-evoked brain activity in response to an acute somatic nociceptive heel lance stimulus

BackgroundElectroencephalography (EEG) can be used in neonates to measure brain activity changes that are evoked by noxious events, such as clinically required immunisations, cannulation and heel lancing for blood tests. EEG provides an alternative approach to infer pain experience in infants compared with more commonly used behavioural and physiological pain assessments. Establishing the generalisability and construct validity of these measures will help corroborate the use of brain-derived outcomes to evaluate the efficacy of new or existing pharmacological and non-pharmacological methods to treat neonatal pain. This study aimed to test whether a measure of noxious-evoked EEG activity called the noxious neurodynamic response function (n-NRF), that was originally derived in a sample of term-aged infants at the Oxford John Radcliffe Hospital, UK, in 2017, can reliably distinguish noxious from non-noxious events in two independent datasets collected at University College London Hospital and at Royal Devon & Exeter Hospital. We aimed to reproduce three published results that use this measure to quantify noxious-evoked changes in brain activity. We used the n-NRF to quantify noxious-evoked brain activity to test (i) whether significantly larger noxious-evoked activity is recorded in response to a clinical heel lance compared to a non-noxious control heel lance procedure; (ii) whether the magnitude of the activity evoked by a noxious heel lance is equivalent in independent cohorts of infants; and (iii) whether the magnitude of the noxious-evoked brain activity increases with postmenstrual age (PMA) in premature infants up to 37 weeks PMA. Positive replication of these studies will build confidence in the use of the n-NRF as a valid and reliable pain-related outcome which could be used to evaluate analgesic efficacy in neonates. The protocol for this study was published following peer review (https://doi.org/10.17605/OSF.IO/ZY9MS). ResultsThe n-NRF magnitude to a noxious heel lance stimulus was significantly greater than to a non-noxious control heel lance stimulus in both the UCL dataset (n = 60; mean difference .88; 95% confidence interval (CI) .64–1.13; p < .0001) and the Exeter dataset (n = 31; mean difference .31; 95% CI .02–.61; p = .02). The mean magnitude and 90% bootstrap confidence interval of the n-NRF evoked by the heel lance did not meet our pre-defined equivalence bounds of 1.0 ± .2 in either the UCL dataset (n = 72; mean magnitude 1.33; 90% bootstrapped CI 1.18–1.52) or the Exeter dataset (n = 35; mean magnitude .92, 90% bootstrapped CI .74–1.22). The magnitude of the n-NRF to the noxious stimulus was significantly positively correlated with PMA in infants up to 37 weeks PMA (n = 65; one-sided Pearson's R, adjusted for site: .24; 95% CI .06–1.00; p = .03). ConclusionsWe have reproduced in independent datasets the findings that the n-NRF response to a noxious stimulus is significantly greater than to a non-noxious stimulus, and that the noxious-evoked EEG response increases with PMA. The pre-defined equivalence bounds for the mean magnitude of the EEG response were not met, though this might be due to either inter-site differences such as the lack of calibration of devices between sites (a true negative) or underpowering (a false negative). This reproducibility study provides robust evidence that supports the use of the n-NRF as an objective outcome for clinical trials assessing acute nociception in neonates. Use of the n-NRF in this way has the potential to transform the way analgesic efficacy studies are performed.

The Mediating Role of Interoceptive Sensitivity in the Relationship between Physical Activity and Depression Symptoms in College Students.

A substantial body of evidence indicates that neurological, psychological, and behavioral health issues are profoundly linked to interoceptive sensitivity. The present study aimed to identify the effects of interoceptive sensitivity on the relationship between physical activity and symptoms of depression in Chinese college students. This study employed a cross-sectional design using convenience sampling. An online self-reported survey was distributed to college students in China. The participants' interoceptive sensitivity, physical activity levels, and depressive symptoms were measured using the MAIA-2, IPAQ-SF, and PHQ-9, respectively. The mediating effect was tested via regression analysis and a parallel mediation model, with bootstrap confidence intervals for indirect effects. The results showed a significant negative correlation between physical activity and depression. A significant positive correlation was observed between physical activity and seven dimensions of interoceptive sensitivity. Conversely, interoceptive sensitivity exhibited a negative correlation with depression. The bootstrap mediation analysis showed that the "not distracting" and "trusting" dimensions of interoceptive sensitivity had significant indirect effects on the relationship between physical activity and depression, suggesting that physical activity might reduce depressive symptoms via these two interoceptive sensitivity dimensions. The findings suggest that interoceptive sensitivity should be integrated into therapeutic interventions, such as physical activity interventions, in the treatment of mental illnesses, particularly depression. Increasing physical activity levels, with a specific focus on enhancing interoceptive modulation, appears to be a promising approach for addressing depression in college students.

Confidence sets for intraclass correlation coefficients in test–retest curve measurements

Evaluating test–retest reliability is crucial in biomechanical research, as it validates experimental results. While methods for reliability of scalar outcome variables are well-established, methods to assess reliability of continuous curve data (such as joint angle trajectories during gait) remain less explored. This study investigates methods for constructing confidence sets for curve-level intraclass correlation coefficients (ICC), which can be expressed as either an ICC curve or an integrated ICC. Currently, no standardised guidelines exist in biomechanics for reporting curve-level ICC uncertainty. Nonparametric bootstrapping techniques are proposed for both the ICC curve’s confidence bands and the integrated ICC’s confidence intervals, and these methods are validated through Monte Carlo simulations, covering various effect sizes and curve characteristics. Additionally, these methods are applied to assess the test–retest reliability of knee kinematics in three different planes during landing of one-leg hops, where less uncertainty is observed for the ICC curve and integrated ICC in the frontal plane compared to other planes. When the entire time domain is of primary empirical interest, we recommend using a rank-based bootstrap confidence band to express ICC uncertainty, as it yields increasingly precise and valid results as the number of individuals increases, with the coverage rate approaching the correct level of 95%. When a single summary metric is of primary interest, we recommend using the integrated ICC along with a typical bootstrap confidence interval based on the normal distribution, as the coverage rate remains adequately accurate and stable at around the correct level of 95% across varying number of individuals.

Relationships of Psychosocial Factors to Diabetes Self-efficacy: A Cross-sectional, Correlational Study.

Self-care in people with diabetes is poor, which could be influenced by positive and negative psychosocial factors. Self-efficacy is an important factor affecting self-care, and depressive symptoms and diabetes distress may directly and indirectly affect self-efficacy. The aim of this study was to examine the relationships of depressive symptoms, diabetes distress, age, sex, self-compassion, resilience, self-esteem, and social support to diabetes self-efficacy and the mediating roles of diabetes distress and depressive symptoms in the relationships among people with diabetes. In this cross-sectional, correlational study, data on all the psychosocial and demographic factors were collected (N = 148; 57.6 years old) through Research Electronic Data Capture in 2023. The PROCESS macro for SPSS was used to address the purpose. The mean score of diabetes self-efficacy was 28.6 (range, 8-40). In 1 model, depressive symptoms were directly and indirectly associated with diabetes self-efficacy through diabetes distress (direct effect, -3.524; t = -3.020, P = .003; indirect effect, -2.089; 95% bootstrap confidence interval, -3.494 to -0.911). In another model, diabetes distress was directly and indirectly associated with diabetes self-efficacy through depressive symptoms (direct effect, -3.778; t = -3.638, P < .001; indirect effect, -0.785; 95% bootstrap confidence interval, -1.868 to -0.089). In addition, self-esteem was associated with both depressive symptoms and diabetes distress. Resilience was associated with diabetes self-efficacy in 1 model. Negative psychological factors were directly and indirectly associated with diabetes self-efficacy. Depressive symptoms, diabetes distress, self-esteem, and resilience can be important targets of interventions to improve diabetes self-efficacy.

SEM Approach to the Mediation Analysis of the Two-Condition Within-Subject Design

The effects of the two-condition within-subject (TCWS) conditional mediation model are developed using the SEM approach. The structural equation model for the within-subject mediator and the within-subject outcome with the specification of a between-subject moderator is developed to derive the indirect effects. Formulas are derived for the indirect effects of two conditions in the TCWS conditional mediation model. These effects are calculated on the rotated outcomes, which are the difference and sum of the outcomes, through two mediators. The derivation is done under both natural and rotated condition approaches. The rotated outcome is expressed as a linear function of the two natural mediators in the natural condition approach, whereas in the rotated condition approach, it is expressed as a function of the two rotated mediators. The total indirect effect on each rotated outcome in both natural and rotated condition approaches consists of two individual indirect effects: one through the within-condition mediator and the other through the crossed-condition mediator. Comparison of two individual indirect effects can reveal the nature of causal relations between conditions and outcomes. The TCWS conditional mediation model is generalized by considering multiple within-subject mediators and multiple between-subject moderators as well as the multiple conditions case. The bootstrapping confidence intervals are used to estimate and test the conditional indirect effects. The total and individual conditional indirect effects are probed by overlaying their bootstrap confidence intervals for given moderator values, and this multi-plot helps the understanding of magnitudes and mechanisms of the moderator on the indirect effects.

Perivascular spaces, plasma GFAP, and speeded executive function in neurodegenerative diseases.

We investigated the effect of perivascular spaces (PVS) volume on speeded executive function (sEF), as mediated by white matter hyperintensities (WMH) volume and plasma glial fibrillary acidic protein (GFAP) in neurodegenerative diseases. A mediation analysis was performed to assess the relationship between neuroimaging markers and plasma biomarkers on sEF in 333 participants clinically diagnosed with Alzheimer's disease/mild cognitive impairment, frontotemporal dementia, or cerebrovascular disease from the Ontario Neurodegenerative Disease Research Initiative. PVS was significantly associated with sEF (c=-0.125±0.054, 95% bootstrap confidence interval [CI] [-0.2309, -0.0189], p=0.021). This effect was mediated by both GFAP and WMH. In this unique clinical cohort of neurodegenerative diseases, we demonstrated that the effect of PVS on sEF was mediated by the presence of elevated plasma GFAP and white matter disease. These findings highlight the potential utility of imaging and plasma biomarkers in the current landscape of therapeutics targeting dementia. Perivascular spaces (PVS) and white matter hyperintensities (WMH) are imaging markers of small vessel disease. Plasma glial fibrillary protein acidic protein (GFAP) is a biomarker of astroglial injury. PVS, WMH, and GFAP are relevant in executive dysfunction from neurodegeneration. PVS's effect on executive function was mediated by GFAP and white matter disease.

Pain Severity and Depressive Symptoms in Endometriosis Patients: Mediation of Negative Body Awareness and Interoceptive Self-Regulation

Endometriosis-related pain may be associated with depressive symptoms. Although a growing body of evidence supports this association, the underlying mechanisms are still largely unclear. Impaired perceptions of bodily external and internal stimuli may be involved in this process. This study aims to assess the mediating role of 2 facets of interoception—the awareness of negative body signals and interoceptive self-regulation—in the association between pain severity and depressive symptoms among women with endometriosis. A total of 301 patients who reported a diagnosis of endometriosis were recruited from an endometriosis and chronic pelvic pain outpatient university clinic and through patient associations and completed self-reported instruments. A parallel mediation analysis was conducted. Almost half of women (48.2%) reported depressive symptoms above the self-rating scale cutoff values. Pain severity significantly predicted depressive symptoms (β = .39, 95% bootstrap confidence interval [CI] [.719, 1.333]). Negative body awareness (β = .121, 95% bootstrap CI [.174, .468]) and interoceptive self-regulation (β = .05, 95% bootstrap CI [.035, .252]) partially mediated this relationship. Our findings indicated that pain may interfere with the perception of the body as a source of calmness and safety, limiting the individual's ability to effectively regulate emotions. Future research should further explore these mechanisms and evaluate the efficacy of interventions focusing on interoceptive sensibility to enhance the psychological well-being of endometriosis patients. PerspectiveThis article investigates for the first time the potential role of 2 facets of interoceptive sensibility in the relationship between pain severity and depressive symptoms in women with endometriosis. These findings may contribute to advancing knowledge about the mechanisms involved in the complex pain-depression cycle.

Evaluating the robustness of an AI pathfinder application on eligibility criteria in multiple myeloma trials using real-world data and historical trials.

Background: Eligibility criteria are pivotal in achieving clinical trial success, enabling targeted patient enrollment while ensuring the trial safety. However, overly restrictive criteria hinder enrollment and study result generalizability. Broadening eligibility criteria enhances the trial inclusivity, diversity and enrollment pace. Liu et al.proposed an AI pathfinder method leveraging real-world data to broaden criteria without compromising efficacy and safety outcomes, demonstrating promise in non-small cell lung cancer trials. Aim: To assess the robustness of the methodology, considering diverse qualities of real-world data and to promote its application. Materials/Methods: We revised the AI pathfinder method, applied it to relapsed and refractory multiple myeloma trials and compared it using two real-world data sources. We modified the assessment and considered a bootstrap confidence interval of the AI pathfinder to enhance the decision robustness. Results & conclusion: Our findings confirmed the AI pathfinder's potential in identifying certain eligibility criteria, in other words, prior complications and laboratory tests for relaxation or removal. However, a robust quantitative assessment, accounting for trial variability and real-world data quality, is crucial for confident decision-making and prioritizing safety alongside efficacy.

Reliability Estimation of Weibull Distribution with Zero-Failure Data

This paper focuses on the reliability estimation of Weibull distributions with zero-failure data. Since no product failure occurred in the tests, the conventional maximum likelihood method was not applicable. Recent methods ignore the estimation of location parameter and tend to be conservative. This study developed a new estimation technique to address these problems. A prior model between the life dispersion boundary and shape parameter is constructed by considering the historical failure data of similar high-reliability products. The failure probabilities for all samples were inferred using the E-Bayesian method, after which the reliability was estimated. Afterward, a confidence interval for reliability was obtained based on the bootstrap confidence interval and modified maximum likelihood method. A Monte Carlo simulation study demonstrated that the proposed method is satisfactory in terms of point estimates, confidence intervals, coverage probabilities, and computational efficiency. Finally, a real engineering example is introduced to illustrate the application of this method.

The generalized order statistics arising from three populations with the lower truncated proportional hazard rate models and its application to the sensitivity to the early disease stage

ABSTRACT In this paper, we present some results to make inference about the parameters of lower truncated proportional hazard rate models with the same baseline distributions based on three independent generalized order statistics samples. Then, especially by considering the results of the diagnostic tests for the non-diseased, early-diseased stage and fully diseased populations, we make inference about sensitivity to the early disease stage parameter. The maximum likelihood estimator, a generalized pivotal estimator and some Bayes estimators are obtained for different structures of prior distributions. The percentile bootstrap confidence interval, a generalized pivotal confidence interval and some Bayesian credible intervals are also presented. A Monte Carlo simulation study is used to evaluate the performances of the obtained point estimators and confidence/credible intervals and two competitors. We use two real datasets to illustrate the proposed methods.

Bootstrap-based confidence intervals for the standard two-sided power distribution

The two-parameter standard two-sided power family of distributions on (0, 1) is considered in this article. We propose bootstrap standard errors for the maximum likelihood estimators, as well as bootstrap confidence intervals for its parameters, once these important statistical measures of accuracy cannot be computed based on first-order asymptotic theory. We consider Monte Carlo simulation experiments to verify the performance of the bootstrap methods, and the numerical results are quite promising. Applications to real data are also considered to illustrate the proposed methodology in practice.

Does Social Support Play a Role in the Expression and Everyday Functioning Impact of Apathy in HIV Disease?

Clinically notable apathy occurs in approximately one-third of persons living with HIV (PLWH). Drawing from psychological theory, this cross-sectional study examined the interplay between apathy and social support in persons with (n = 143) and without (n = 61) HIV disease. Analyses were conducted using multiple regression and mediation procedures with 95th percentile bootstrap confidence intervals. Positive HIV serostatus and lower social support were associated with more frequent apathy, independent of other mood symptoms. Social support did not moderate apathy's associations with everyday functioning among PLWH, but post hoc analyses revealed that apathy mediated the relationship between social support and everyday functioning among PLWH. Stronger social support may provide a buffer against the frequency of apathy symptoms in persons with and without HIV disease. The relationship between lower social support and poorer everyday functioning in HIV might be partly explained by apathy. Longitudinal research is needed to examine the mechanisms of these relationships.