Individual-level Heterogeneity Research Articles

An adaptive decision support system for outpatient appointment scheduling with heterogeneous service times.

Appointment scheduling (AS) plays a crucial role in outpatient clinic management. Traditional methods involve patient grouping using pre-defined rules and scheduling based on these groups. However, pre-defined rules may not adequately capture the heterogeneity in patients' service times (i.e., consultation duration). Advanced machine learning (ML) methods can address individual-level heterogeneity but pose challenges for practical scheduling. To strike a balance, we propose a data-driven AS decision support system, Cluster-Predict-Schedule (CPS), integrating both supervised and unsupervised ML for efficient patient grouping and scheduling. The novelty of CPS lies in its adaptability to service time heterogeneity through a data-driven approach, determining patient groups based on data rather than pre-defined rules. Additionally, CPS includes a generic and efficient algorithm for generating appointment templates adaptable to any number of patient groups. Our system's efficacy is demonstrated using a real-world dataset. Evaluated by the weighted sum of patient wait times, physician idle time, and overtime, CPS achieves up to 15.0% cost reduction compared to the FCFA (first-call, first-appointment) scheme and over 4.7% savings against the common New/Return classification with traditional sequencing candidate (TSC) rules. In addition, CPS enhances outpatient operational efficiency without compromising fairness.

Multiple sclerosis subgroups: Data-driven clusters based on patient-reported outcomes and a large clinical sample

Background: While standard clinical assessments provide great value for people with multiple sclerosis (PwMS), they are limited in their ability to characterize patient perspectives and individual-level symptom heterogeneity. Objectives: To identify PwMS subgroups based on patient-reported outcomes (PROs) of physical, cognitive, and emotional symptoms. We also sought to connect PRO-based subgroups with demographic variables, functional impairment, hypertension and smoking status, traditional qualitative multiple sclerosis (MS) symptom groupings, and neuroperformance measurements. Methods: Using a cross-sectional design, we applied latent profile analysis (LPA) to a large database of PROs; analytic sample N = 6619). Results: We identified nine distinct MS subtypes based on PRO patterns. The subtypes were primarily categorized into low, moderate, and high mobility impairment clusters. Approximately 70% of participants were classified in a low mobility impairment group, 10% in a moderate mobility impairment group, and 20% in a high mobility impairment group. Within these subgroups, several unexpected patterns were observed, such as high mobility impairment clusters reporting low non-mobility impairment. Conclusions: The present study highlights an opportunity to advance precision medicine approaches in MS. Combining PROs with data-driven methodology allows for a cost-effective and personalized characterization of symptom presentations. that can inform clinical practice and future research designs.

The effects of poor housing conditions on depressive symptoms in persons with disabilities: Do residence type and neighborhood resources matter?

BackgroundPoor housing conditions pose significant risks to the health of persons with disabilities. However, it is not well understood how and for whom the relationship between housing conditions and health is more pronounced. ObjectiveThis study aims to estimate the association between poor housing conditions and psychological health, and to explore whether residential characteristics, such as residence type and proximity to community resources, mitigate these risks for community-dwelling adults with disabilities. MethodsData were obtained from three waves of the Disability and Life Dynamic Panel (n = 5,165), a nationally representative study of individuals with disabilities in Korea. Our sample were limited to those aged 20 or older for the purpose of this study. Individual-level fixed effect analyses were conducted to assess the longitudinal association between poor housing conditions and depressive symptoms, accounting for individual-level heterogeneity. We also tested the moderating effects of the residential characteristics, including residence type and proximity to community resources. ResultsPoor housing conditions, characterized by structural unsafety and inadequate ventilation, lighting, and noise protection, were associated with increased depressive symptoms among adults with disabilities. The negative impact of poor housing conditions on depressive symptoms was less pronounced for those living close to community services or in apartment complexes where housing conditions are professionally managed. ConclusionsThe study indicates that the quality of housing and neighborhood environments affects the psychological health of adults with disabilities. These findings support for the need for place-based interventions aimed at improving the residential environments of community-dwelling adults with disabilities.

Transportability of model-based estimands in evidence synthesis.

In evidence synthesis, effect modifiers are typically described as variables that induce treatment effect heterogeneity at the individual level, through treatment-covariate interactions in an outcome model parametrized at such level. As such, effect modification is defined with respect to a conditional measure, but marginal effect estimates are required for population-level decisions in health technology assessment. For noncollapsible measures, purely prognostic variables that are not determinants of treatment response at the individual level may modify marginal effects, even where there is individual-level treatment effect homogeneity. With heterogeneity, marginal effects for measures that are not directly collapsible cannot be expressed in terms of marginal covariate moments, and generally depend on the joint distribution of conditional effect measure modifiers and purely prognostic variables. There are implications for recommended practices in evidence synthesis. Unadjusted anchored indirect comparisons can be biased in the absence of individual-level treatment effect heterogeneity, or when marginal covariate moments are balanced across studies. Covariate adjustment may be necessary to account for cross-study imbalances in joint covariate distributions involving purely prognostic variables. In the absence of individual patient data for the target, covariate adjustment approaches are inherently limited in their ability to remove bias for measures that are not directly collapsible. Directly collapsible measures would facilitate the transportability of marginal effects between studies by: (1) reducing dependence on model-based covariate adjustment where there is individual-level treatment effect homogeneity or marginal covariate moments are balanced; and (2) facilitating the selection of baseline covariates for adjustment where there is individual-level treatment effect heterogeneity.

TripChain2RecDeepSurv: A novel framework to predict transit users’ lifecycle behavior status transitions for user management

Transit users’ lifecycle behavior pattern transition reflects the continuous and multi-phase changes in how frequently and regularly users utilize public transit over their lifetime. Predicting transit users’ lifecycle behavior pattern transition is vital for enhancing the efficiency and responsiveness of transportation systems. Thus, this study incorporates lifecycle analysis in predicting long-term sequential behavioral pattern transition processes to go beyond just examining user churning at a single point in time. Specifically, this study proposes the TripChain2RecDeepSurv, a novel model that pioneers the individual-level analysis of lifecycle behavior status transitions (LBST) within public transit systems. The TripChain2RecDeepSurv is composed of (1) the TripChain2Vec module for encoding transit users’ trip chains; (2) the self-attention Transformer module for exploring the latent features related to spatiotemporal patterns; (3) the recurrent deep survival analysis module for predicting LBSTs. We demonstrate TripChain2RecDeepSurv’s predictive performance for empirical analysis by employing Shenzhen Bus data. Our model achieves a 74.39% accuracy rate in churn determination and over 80% accuracy in status sequence identification on the churn path. In addition, our findings highlight the segmented nature of Kaplan-Meier curves and identify the optimal intervention time against the user churning process. Meanwhile, the proposed model provides individual-level heterogeneity analysis, which emphasizes the significance of customizing user engagement strategies, advocating for interventions that extend users’ engagement in patterns with high-frequency transit usage to curb the transition to less frequent travel usage.

The importance of sampling frequency for estimates of well-being dynamics

Using a high-frequency panel survey, we examine the sensitivity of estimated self-reported well-being (SWB) dynamics to using monthly, quarterly, and yearly data. This is an important issue if SWB is to be used to evaluate policy. Results from autoregressive models that account for individual-level heterogeneity indicate that the estimated persistence using yearly data is near zero. However, estimated persistence from monthly and quarterly data is substantial. We estimate that persistence to shocks typically lasts around six months and has a net present value of 75–80 per cent of the contemporaneous effect. Estimates are similar for different domains of SWB.

Children's bullying victimization and the acculturative stress of immigrant mothers in Korea: Exploring heterogeneity by mother's country of origin.

Over the past three decades, the number of multicultural families in Korea, defined as a family consisting of a native Korean and a marriage immigrant, has increased significantly. Although bullying victimization among multicultural family youth is rightfully a growing concern, less is known about the effects bullying has on immigrant mothers of children who have been bullying victims. Using data from the Multicultural Adolescents Panel Study, this study investigates whether children's bullying victimization is associated with immigrant mothers' acculturative stress and whether this association differs depending on mothers' country of origin (China, Japan, and Southeast Asian countries). Fixed effects estimates revealed that children's bullying victimization is positively associated with their immigrant mother's acculturative stress, and this association is robust to controlling for unobserved time-constant individual-level heterogeneity. When stratified by mother's country of origin, the association was larger and statistically significant only among Southeast Asian mothers. No associations were observed among Japanese and Chinese mothers. Our findings suggest that interventions aiming to support bullied children should be expanded to also support their immigrant mothers. Policymakers may wish to consider the specific backgrounds and contexts of immigrant mothers, with special attention to Southeast Asian women. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Partisan Perspectives on Inflation: Exploring Bias in Economic Expectations

Inflation expectations are important determinants of future inflation and individual consumer behavior. Recent attention has been devoted to individual-level heterogeneity in inflation expectations. I consider political partisanship as a source of heterogeneity and question whether expectations are biased by partisanship. I find that they are, i.e., that individuals from the president’s political party expect lower inflation relative to members of the opposing party (this difference is statistically insignificant during the Bush presidency), and that this result cannot be explained by additional sources of heterogeneity. I also examine whether belonging to the president’s political party affects the rationality of expectations and find, first, that individuals from the president’s political party base their expectations more closely on CPI relative to the opposing party (although this difference is too small to be statistically distinguishable during the Bush and Biden administrations), and second, that members of the president’s party have more accurate expectations.

Mind the Gap: Why Wealthy Voters Support Brexit

Abstract Wealth provides self-insurance against financial risk, reducing risk aversion. We apply this insurance mechanism to electoral behaviour, arguing that a voter who desires a change to the status quo and who is wealthy is more likely to vote for change than a voter who lacks the same self-insurance. We apply this argument to the case of Brexit in the UK, which has been widely characterized as a vote by the ‘economically left-behind’. Our results show that individuals who lacked wealth are less likely to support leaving the EU, explaining why so many Brexit voters were wealthy, in terms of their property wealth. We corroborate our theory using two panel surveys, accounting for unobserved individual-level heterogeneity, and by using a survey experiment. The findings have implications for the potential broader role of wealth-as-insurance in electoral behaviour and for understanding the Brexit case.

From shutdown to reopening: unpacking the determinants of tourism business reopening in the face of adversity

ABSTRACT The coronavirus (COVID-19) pandemic and its associated lockdowns put many tourism businesses on hold. Although these lockdowns have been lifted, not all tourism entrepreneurs reopened their businesses. While prior research has extensively explored the post-pandemic recovery of tourism businesses, there has been relatively limited attention given to the determinants of tourism entrepreneurs to reopen their businesses post-crisis. Drawing on upper echelons theory, this paper explores the role of tourism entrepreneurs’ age in driving the decision to reopen their businesses in the face of adversity. Empirical evidence from a two-wave multi-informant survey involving 134 entrepreneurs in small and medium-sized tourism enterprises in China reveals that older entrepreneurs were more likely to reopen their businesses after the lockdowns were lifted. This relationship is even more pronounced for entrepreneurs who perceive less uncertainty or exhibit higher optimism. This paper represents one of the pioneering attempts to uncover the individual-level heterogeneity in determinants of tourism business reopening against the backdrop of adversity – a crucial foundation for understanding business recovery processes. It offers valuable insights that can assist small and medium-sized tourism enterprises to enhance their preparedness and responsiveness to probable future crises.

Tapping into Talent: Coupling Education and Innovation Policies for Economic Growth

Abstract How do innovation and education policy affect individual career choices and aggregate productivity? This paper analyses the effect of R&D subsidies and higher education policy on productivity growth through the supply of innovative talent. We put scarce talent, higher education attainment, and career choice at the centre of a new endogenous growth framework with individual-level heterogeneity in talent, financial resources, and preferences. We link the model to micro-level data from Denmark on the backgrounds of who obtains a PhD and becomes an inventor and the outcomes of a set of policy interventions. We find that R&D subsidies can be strengthened when combined with higher education subsidies, which enable talented but poor youth to pursue a career in research. Education and innovation policies not only alleviate different frictions, but also impact innovation at different time horizons. Education policy is more effective in societies with higher income inequality.

Cost-Effective and Scalable Clonal Hematopoiesis Assay Provides Insight into Clonal Dynamics

Clonal hematopoiesis of indeterminate potential (CHIP) is a common age-related phenomenon that occurs when hematopoietic stem cells acquire mutations in a select set of genes commonly mutated in myeloid neoplasia which then expand clonally. Current sequencing assays to detect CHIP mutations are not optimized for the detection of these variants and can be cost-prohibitive when applied to large cohorts or serial sequencing. In this study, an affordable (∼$8 per sample), accurate, and scalable sequencing assay for CHIP is introduced and validated. The efficacy of the assay is demonstrated by identifying CHIP mutations in a cohort of 456 individuals with DNA collected at multiple timepoints in the Vanderbilt BioVU biobank and quantifying clonal expansion rates over time. A total of 101 individuals with CHIP/CCUS were identified, and individual-level clonal expansion rate was calculated using the variant allele fraction (VAF) at both timepoints. Differences in clonal expansion rate by driver gene were observed, but there was also significant individual-level heterogeneity, emphasizing the multifactorial nature of clonal expansion. Additionally, the study explores mutation co-occurrence and clonal competition between multiple driver mutations.

Partner's contribution to housework and couple bonding activities among Korean working women: Heterogeneity by socioeconomic status

The present study investigates: (a) how a partner's contribution to housework is associated with couple bonding activities among Korean women in dual-earner couples and (b) whether this association varies by socioeconomic status. Using eight waves from the Korean Longitudinal Survey of Women & Families (N = 5758), we estimated fixed effects models to account for individual-level heterogeneity. Engagement in couple bonding activities was measured by the frequency of physical and cultural activities with a partner. Fixed effects estimates showed that a partner's contribution to housework is positively associated with engagement in physical and cultural activities with a partner. The association between a partner's contribution to housework and physical and cultural activities was more pronounced among women in dual-earner couples in which the woman was highly educated. The association for cultural activities, not physical activities, was amplified by household income. This study supports the notion that a more equal distribution of housework is important for improving the quality of life in a marriage.

Power Analysis for Human Melatonin Suppression Experiments.

In humans, the nocturnal secretion of melatonin by the pineal gland is suppressed by ocular exposure to light. In the laboratory, melatonin suppression is a biomarker for this neuroendocrine pathway. Recent work has found that individuals differ substantially in their melatonin-suppressive response to light, with the most sensitive individuals being up to 60 times more sensitive than the least sensitive individuals. Planning experiments with melatonin suppression as an outcome needs to incorporate these individual differences, particularly in common resource-limited scenarios where running within-subjects studies at multiple light levels is costly and resource-intensive and may not be feasible with respect to participant compliance. Here, we present a novel framework for virtual laboratory melatonin suppression experiments, incorporating a Bayesian statistical model. We provide a Shiny web app for power analyses that allows users to modify various experimental parameters (sample size, individual-level heterogeneity, statistical significance threshold, light levels), and simulate a systematic shift in sensitivity (e.g., due to a pharmacological or other intervention). Our framework helps experimenters to design compelling and robust studies, offering novel insights into the underlying biological variability in melatonin suppression relevant for practical applications.

Perceived social position, active engagement with life, and depressive symptoms among older adults

RationaleDespite the existing literature on the relationship between perceived social position (PSP) and depressive symptoms, there remain gaps in our understanding, particularly regarding the potential for asymmetric effects of increases and decreases in PSP and the underlying mechanisms involved. ObjectiveThis study aims to examine whether increases and decreases in PSP are differentially associated with depressive symptoms and to explore the potential mediating role of active engagement with life in these associations. MethodsThis study utilized data from the Korean Longitudinal Study of Aging (KLoSA), collected between 2008 and 2018, involving a sample of 3506 individuals aged 65 or older. Asymmetric fixed effects (FE) models were employed, which enable the estimation of differential effects for increases and decreases in PSP, while accounting for unobserved individual-level heterogeneity. To assess the mediating role of active engagement in life, Sobel mediation tests were conducted. ResultsThe asymmetric FE estimates revealed a stronger association between decreases in PSP and increases in depressive symptoms compared to the association between increases in PSP and decreases in depressive symptoms. The Sobel mediation tests indicated that formal social activities had the most substantial mediating effect, explaining 14% and 9% of the total effect mediated for increased and decreased PSP and depressive symptoms, respectively. Leisure/hobby activities explained 10% and 4% of the total effect mediated for increased and decreased PSP and depressive symptoms, respectively. ConclusionThis study provides evidence that increases and decreases in PSP have differential effects on depressive symptoms among older adults in Korea. Policy interventions aimed at improving the psychological well-being of older adults should prioritize efforts to both enhance PSP and minimize declines, as the latter can have a stronger negative impact on depressive symptoms. Active engagement in life may serve as a potential pathway for achieving the desired effects.

Children's bullying victimization and maternal suicidal ideation among multicultural families in South Korea: Heterogeneity by family socioeconomic status

RationaleChildren from multicultural families in Korea are vulnerable to bullying victimization. Despite growing evidence on the mental health consequences of bullying victimization for victims, little is known about the spillover effects on their immigrant mothers. ObjectiveThis study examined the association between children's bullying victimization and their immigrant mothers' suicidal ideation. The potential moderating role of family socioeconomic status was also investigated. MethodsUsing nine waves of the Multicultural Adolescents Panel Study spanning from 2011 to 2019 (N = 1466), this study estimated individual fixed effects models to control for unobserved individual-level heterogeneity. Interaction models were used to investigate potential heterogeneity by family socioeconomic status, including maternal education, household income, and maternal occupational status. ResultsFixed effects estimates revealed that children's bullying victimization is associated with an increased likelihood of suicidal ideation among marriage migrant mothers (b = 0.012, p < 0.05), even after controlling for unobserved time-invariant confounders as well as a set of time-varying covariates. Family socioeconomic status moderated this association. The association between children's bullying victimization and immigrant mothers' suicidal ideation was stronger for those with low levels of education and household income. No such moderating effects were observed for maternal occupation. ConclusionsThe findings of this study suggest that efforts to address the mental health consequences of bullying victimization among multicultural family children should extend beyond the victim to their immigrant mothers. When developing interventions to reduce suicidal ideation among immigrant mothers whose children have been victimized, policymakers may wish to consider the moderating role of family socioeconomic status.

The death of an adult child and trajectories of parental depressive symptoms: A gender-based longitudinal analysis

RationaleDespite the existing body of research on the impact of child bereavement, little is known about whether time to the death of an adult child is longitudinally associated with changes in depressive symptoms among older parents. ObjectiveThis study examines (a) trajectories of depressive symptoms before and after the loss of an adult child and (b) whether these trajectories differ across parent-child gender dyads (father-son, father-daughter, mother-son, and mother-daughter). MethodsUsing eight waves of the Korean Longitudinal Study of Ageing (KLoSA), this study employs fixed effects models to mitigate potential bias due to unobserved individual-level heterogeneity. Gender-stratified fixed effects models were estimated to investigate potential heterogeneity in the trajectories of depressive symptoms by parent-child gender dyads. ResultsThe result of this study revealed that depressive symptoms increased within the first year following the loss of an adult child among bereaved parents. Within a year of the loss of a child, both mothers and fathers experienced an increase in depressive symptoms. However, only fathers experienced lasting effects for up to two years. Different patterns in psychological adjustment to bereavement were observed across different parent-child gender dyads. Among daughter-bereaved fathers, depressive symptoms surged within the first year and persisted even beyond the fourth year of loss. In contrast, for other dyads, only an immediate rise in depressive symptoms within the first year of loss was observed. ConclusionsThe loss of an adult child increases the depressive symptoms of parents. This study highlights the importance of considering the different trajectories of psychological adjustment to bereavement, particularly based on parent-child gender dyads, when formulating policies for providing psychological support to older parents who have experienced the loss of their child.

GENDERED TRAJECTORIES OF DEPRESSIVE SYMPTOMS IN OLDER KOREAN PARENTS BEREAVED OF AN ADULT CHILD

Abstract Despite the existing body of research on the impact of child bereavement, little is known about whether time to the death of an adult child is associated with changes in depressive symptoms among older Korean parents. This study examines (a) trajectories of depressive symptoms before and after the loss of an adult child and (b) whether these trajectories differ across parent-child pairs (father-son, father-daughter, mother-son, and mother-daughter). Using eight waves of the Korean Longitudinal Study of Ageing (KLoSA), the study employs fixed effects models to mitigate potential bias due to unobserved individual-level heterogeneity. The result of this study revealed that depressive symptoms increased within the first year following the loss of an adult child among bereaved parents. Considering the gender of both the parent and the deceased child, differences in psychological adjustment to bereavement were observed in different dyads. Depressive symptoms surged within the first year and persisted even beyond the fourth year of loss among daughter-bereaved fathers, while only an immediate rise in depressive symptoms within the first year of loss occurred for other pairs. Given prevailing gender role socialization in the Korean context, men’s conformity to masculinity norms and the traditional expectation for daughters to provide emotional support may contribute to the long-term increase in depressive symptoms for fathers who have lost a daughter. Thus, in societies where Confucian gender culture is ingrained as a social norm, policies for the psychological support of older parents who have lost adult children must consider the different trajectories of parent-child relationships.

Machine learning identifies risk factors associated with long-term sick leave following COVID-19 in Danish population

BackgroundPost COVID-19 condition (PCC) can lead to considerable morbidity, including prolonged sick-leave. Identifying risk groups is important for informing interventions. We investigated heterogeneity in the effect of SARS-CoV-2 infection on long-term sick-leave and identified subgroups at higher risk.MethodsWe conducted a hybrid survey and register-based retrospective cohort study of Danish residents who tested positive for SARS-CoV-2 between November 2020 and February 2021 and a control group who tested negative, with no known history of SARS-CoV-2. We estimated the causal risk difference (RD) of long-term sick-leave due to PCC and used the causal forest method to identify individual-level heterogeneity in the effect of infection on sick-leave. Sick-leave was defined as >4 weeks of full-time sick-leave from 4 weeks to 9 months after the test.ResultsHere, in a cohort of 88,818 individuals, including 37,482 with a confirmed SARS-CoV-2 infection, the RD of long-term sick-leave is 3.3% (95% CI 3.1% to 3.6%). We observe a high degree of effect heterogeneity, with conditional RDs ranging from −3.4% to 13.7%. Age, high BMI, depression, and sex are the most important variables explaining heterogeneity. Among three-way interactions considered, females with high BMI and depression and persons aged 36–45 years with high BMI and depression have an absolute increase in risk of long-term sick-leave above 10%.ConclusionsOur study supports significant individual-level heterogeneity in the effect of SARS-CoV-2 infection on long-term sick-leave, with age, sex, high BMI, and depression identified as key factors. Efforts to curb the PCC burden should consider multimorbidity and individual-level risk.

Double jeopardy: Exploring the moderating effect of educational mismatch in the relationship between work-family conflict and depressive symptoms among Korean working women

RationaleDespite a growing body of empirical evidence on the detrimental effects of work-family conflict (WFC) on psychological health, little attention has been given to whether educational mismatch in the workplace, which refers to the perceived level of match between one's attained education and the required educational level for a position, may exacerbate these effects. ObjectiveThe purpose of this study was to examine the relationship between WFC, educational mismatch, and depressive symptoms in Korean working women, with a particular focus on the potential moderating effects of educational mismatch on the association between WFC and depressive symptoms. MethodsThe data utilized for this study were collected from 5174 married working women over five waves (16,610 person-observations) of the Korean Longitudinal Survey of Women and Families spanning 8 years between 2012 and 2020. Fixed effects (FE) models were estimated to account for unobserved individual-level heterogeneity. ResultsFE estimates indicated that WFC is associated with an increase in depressive symptoms, even after accounting for unobserved confounding factors and time-varying covariates. The interaction model provides evidence for the moderating role of educational mismatch in the association between WFC and depressive symptoms. The positive association between WFC and depressive symptoms was more pronounced among those who perceive themselves as “overeducated.” The estimated coefficient for the association was about 45% larger for those who perceive themselves as “overeducated” than their “well-matched” counterparts. ConclusionThe study's findings suggest a robust link between WFC and depressive symptoms and further elaborate on how this association varies depending on educational mismatch. In Korea, where conservative gender role norms of female-caregiver ideology are still prevalent, WFC and educational mismatch can act as double jeopardy, exacerbating the mental health of working women.