Search results for "mediation analysi"
showing 6 items of 36 documents
Insights into the derivative-based method for nonlinear mediation models
2022
Associational mediation analysis has generally relied on the linearity of models to estimate the indirect effect as a product of regression coefficients. Very few examples of generalisations to nonlinear settings have been proposed, including a derivative-based method that, however, is far from being widely spread among scholars. In this paper, we clarify some aspects of such an approach to nonlinear mediation models, which have not been addressed by the previous literature. In addition, we run a simulation study to compare confidence intervals for the indirect effect obtained through different approaches.
Examining mediators of change in wellbeing, stress, and depression in a blended, Internet-based, ACT intervention for university students
2020
A coach-guided Acceptance and Commitment Therapy (ACT) intervention that uses a blended approach of two face-to-face and five online sessions (iACT; N = 33) has been found to be more effective than a waiting-list control condition (WLC; N = 35) at enhancing the wellbeing of university students while also reducing stress and depression. The present study explored possible mediators of change that may account for the outcomes of the study. Mediation analyses revealed that changes in the non-reactivity subscale of mindfulness mediated changes in wellbeing, depression, and stress in the iACT group. In addition, changes in the sense of coherence subscale of meaningfulness mediated changes in all…
Longitudinal mediation analysis with structural and multilevel models: associational and causal perspectives
2022
Prenatal air pollution exposure and growth and cardio-metabolic risk in preschoolers
2020
Objectives: We investigated the association between outdoor air pollutants exposure in the first trimester of pregnancy, and growth and cardio-metabolic risk at four years of age, and evaluated the mediating role of birth weight. Methods: We included mother-child pairs (N = 1,724) from the Spanish INMA birth cohort established in 2003-2008. First trimester of pregnancy nitrogen dioxide (NO2) and fine particles (PM2.5) exposure levels were estimated. Height, weight, waist circumference, blood pressure, and lipids were measured at four years of age. Body mass index (BMI) trajectories from birth to four years were identified. Results: Increased PM2.5 exposure in the first trimester of pregnanc…
Personal and Environmental Risk Factors at Birth and Hospital Admission: Direct and Vitamin D-Mediated Effects on Bronchiolitis Hospitalization
2021
Abstract: Seasonal variations in UV-B radiation may influence vitamin D status, and this, in turn, may influence the risk of bronchiolitis hospitalization. The aim of this study was using a causal inference approach to investigate, simultaneously, the interrelationships between personal and environmental risk factors at birth/hospital admission (RFBH), serum vitamin D levels and bronchiolitis hospitalization. A total of 63 children (<2 years old) hospitalized for bronchiolitis (34 RSV-positive) and 63 controls were consecutively enrolled (2014-2016). Vitamin D levels and some RFBH (birth season, birth weight, gestational age, gender, age, weight, hospitalization season) were recorded. The d…
Sensitivity Analysis in Nonrandomized Longitudinal Mediation Analysis
2021
Mediation analysis relies on an untestable assumption of the no omitted confounders, which posits that an omitted variable that confounds the relationships between the antecedent, mediator, and outcome variables cannot exist. One common model in alcohol addiction studies is a nonrandomized latent growth curve mediation model (LGCMM), where the antecedent variable is not randomized, the two covarying mediators are latent intercept and slope modeling longitudinal effect of the repeated measures mediator, and an outcome variable that measures alcohol use. An important gap in the literature is lack of sensitivity analysis techniques to assess the effect of the violation of the no omitted confou…