A Tractable State-Space Model for Symmetric Positive-Definite Matrices

Bayesian analysis of state-space models includes computing the posterior distribution of the system's parameters as well as filtering, smoothing, and predicting the system's latent states. When the latent states wander around $\mathbb{R}^n$ there are several well-known modeling components and computational tools that may be profitably combined to achieve these tasks. However, there are scenarios, like tracking an object in a video or tracking a covariance matrix of financial assets returns, when the latent states are restricted to a curve within $\mathbb{R}^n$ and these models and tools do not immediately apply. Within this constrained setting, most work has focused on filtering and less attention has been paid to the other aspects of Bayesian state-space inference, which tend to be more challenging. To that end, we present a state-space model whose latent states take values on the manifold of symmetric positive-definite matrices and for which one may easily compute the posterior distribution of the latent states and the system's parameters, in addition to filtered distributions and one-step ahead predictions. Deploying the model within the context of finance, we show how one can use realized covariance matrices as data to predict latent time-varying covariance matrices. This approach out-performs factor stochastic volatility.Comment: 22 pages: 16 pages main manuscript, 4 pages appendix, 2 pages reference

How should we measure psychological resilience in sport performers?

Psychological resilience is important in sport because athletes must constantly withstand a wide range of pressures to attain and sustain high performance. To advance psychologists’ understanding of this area, there exists an urgent need to develop a sport-specific measure of resilience. The purpose of this paper is to review psychometric issues in resilience research and to discuss the implications for sport psychology. Drawing on the wider general psychology literature to inform the discussion, the narrative is divided into three main sections relating to resilience and its assessment: adversity, positive adaptation, and protective factors. The first section reviews the different ways that adversity has been measured and considers the potential problems of using items with varying degrees of controllability and risk. The second section discusses the different approaches to assessing positive adaptation and examines the issue of circularity pervasive in resilience research. The final section explores the various issues related to the assessment of protective factors drawing directly from current measures of resilience in other psychology sub-disciplines. The commentary concludes with key recommendations for sport psychology researchers seeking to develop a measure of psychological resilience in athletes

A methodological review of resilience measurement scales

BACKGROUND: The evaluation of interventions and policies designed to promote resilience, and research to understand the determinants and associations, require reliable and valid measures to ensure data quality. This paper systematically reviews the psychometric rigour of resilience measurement scales developed for use in general and clinical populations. METHODS: Eight electronic abstract databases and the internet were searched and reference lists of all identified papers were hand searched. The focus was to identify peer reviewed journal articles where resilience was a key focus and/or is assessed. Two authors independently extracted data and performed a quality assessment of the scale psychometric properties. RESULTS: Nineteen resilience measures were reviewed; four of these were refinements of the original measure. All the measures had some missing information regarding the psychometric properties. Overall, the Connor-Davidson Resilience Scale, the Resilience Scale for Adults and the Brief Resilience Scale received the best psychometric ratings. The conceptual and theoretical adequacy of a number of the scales was questionable. CONCLUSION: We found no current 'gold standard' amongst 15 measures of resilience. A number of the scales are in the early stages of development, and all require further validation work. Given increasing interest in resilience from major international funders, key policy makers and practice, researchers are urged to report relevant validation statistics when using the measures

Video as an Implement of Democratic Action and Social Change

The decision to favor socially relevant work over personal introspection was an evolutionary process, where the pressing needs of external problems eclipsed individual concerns. Self-absorption accomplishes just that, but addressing one's abilities in a direction of change is the only way an environment occurs in which change can emerge. I consciously selected the video media as my art form for its native power and potential for subversion. It is not the precious object that only those who frequent the galleries may see. It is infinitely reproducible and as impermanent as life itself. It's roots are in TV, the modern day popular cultural icon ensconced as a trusted friend in every livingroom in America. One of the struggles I experienced with this piece was foregoing the obvious emotional appeal for the educational value, although my intent was to demonstrate the tenacity of those who were fighting what many considered a losing battle to preserve their heritage and lands against racism, greed and corrupt officials. In my compulsion to record things accurately, the lyricism of the piece suffered, transforming it into an intellectual exercise. That in itself is not bad, but relatively joyless. Ethnographic documentary is born from compassion, not politics, although they necessarily depend on one another, and the balance is delicate. &nbsp;</p

Enhancing communication between dementia care staff and their residents: an arts-inspired intervention

Objectives: The arts are increasingly recognised as important and beneficial activities for people living with dementia. However, there is little peer-reviewed published research exploring arts-based learning for dementia care staff. In response, this paper explores (a) how dementia care staff describe forms of communication in care settings, and (b) the impact on communication following four sessions of ‘Creative Conversations’, an arts-based intervention for skills development. Method: Fourteen care homes received the intervention, delivered as 4 × 2 hour sessions. The intervention uses a range of activities (e.g. poetry, film, music, art making). Twenty–eight care staff were opportunistically sampled (mean age = 42.29), and provided pre-post qualitative data, obtained through interviews. Transcripts were analysed thematically. Results: At baseline, the dominant ‘task-focussed’ nature of care work was described as a barrier to communication, challenging opportunities for developing meaningful relationships with residents. Post-intervention, three primary themes were identified regarding improving communication: (1) learning through the arts (secondary themes: simplicity and subtlety, innovation in communication, and strengthening the role of non-verbal communication), (2) Enhancing creative approaches to care (secondary themes: element of surprise, confidence to experiment and catalyst for communication) and (3) professional introspection (secondary themes: development of empathy, sharing knowledge and experiences and a new appreciation). Conclusions: The intervention validated staff skills and confidence, enabling meaningful interactions that could be creative, ‘in the moment’, spontaneous and improvised. This arts-based intervention, which departs from formal education and fact-based learning may be particularly useful for the development of the dementia care workforce

Factors of resilience in informal caregivers of people with dementia from integrative international data analysis

Background/Aims: Although caring for a person with dementia can be stressful, some caregivers appear to experience few negative consequences to their well-being. This study aimed to examine what proportion of caregivers demonstrates resilience under different challenging circumstances and to identify factors related to their resilience. Methods: Baseline data from 4 studies from the Netherlands and UK among informal caregivers of people with dementia were harmonized and integrated. Caregiver resilience was defined as high levels of psychological well-being despite different types of high caregiving demands. Multivariate regression analyses identified factors significantly related to caregiver resilience. Results: The integrated data set included 15 harmonized variables with data from 1,048 caregivers facing a high care demand. The prevalence of resilience varied between 35 and 43%, depending on the demand for high care. Being a male caregiver, caring for a female, living apart from your relative, and low caregiver burden were positively related to caregiver resilience. Conclusion: Caregivers have the capacity to demonstrate resilience despite significant challenges. This study demonstrates how harmonization of data from multiple existing studies can be used to increase power and explore the consistency of findings. This contributes to a better understanding of which factors are likely to facilitate caregiver resilience and offers insights for developing services

An International Multi-Stakeholder Delphi Survey Study on the Design of Disease Modifying Parkinson’s Disease Trials

Background: Design of disease modification (DM) trials for Parkinson’s disease (PD) is challenging. Successful delivery requires a shared understanding of priorities and practicalities. Objective: To seek stakeholder consensus on phase 3 trials’ overall goals and structure, inclusion criteria, outcome measures, and trial delivery and understand where perspectives differ. Methods: An international expert panel comprising people with Parkinson’s (PwP), care partners (CP), clinical scientists, representatives from industry, funders and regulators participated in a survey-based Delphi study. Survey items were informed by a scoping review of DM trials and PwP input. Respondents scored item agreement over 3 rounds. Scores and reasoning were summarized by participant group each round until consensus, defined as≥70% of at least 3 participant groups falling within the same 3-point region of a 9-point Likert scale. Results: 92/121 individuals from 13 countries (46/69 PwP, 13/18 CP, 20/20 clinical scientists, representatives from 8/8 companies, 4/5 funders, and 1/1 regulator) completed the study. Consensus was reached on 14/31 survey items: 5/8 overall goals and structure, 1/8 Eligibility criteria, 7/13 outcome measures, and 1/2 trial delivery items. Extent of stakeholder endorsement for 428 reasons for scores was collated across items. Conclusions: This is the first systematic multi-stakeholder consultation generating a unique repository of perspectives on pivotal aspects of DM trial design including those of PwP and CP. The panel endorsed outcomes that holistically measure PD and the importance of inclusive trials with hybrid delivery models. Areas of disagreement will inform mitigating strategies of researchers to ensure successful delivery of future trials