Expectations Concordance and Stock Market Volatility: Knightian Uncertainty in the Year of the Pandemic

This study introduces a novel index based on expectations concordance for explaining stock-price volatility when novel events that are each somewhat unique cause unforeseeable change and Knightian uncertainty in the process driving outcomes. Expectations concordance measures the degree to which KU events are associated with directionally similar expectations of future returns. Narrative analytics of daily news reports allow for the assessment of bullish versus bearish views in the stock market. Increases in expectations concordance across all KU events results in reinforcing effects and an increase in stock market volatility. Lower expectations concordance produces a stabilizing effect wherein the offsetting views reduce market volatility. The empirical findings hold for ex post and ex ante measures of volatility and for OLS and GARCH estimates.

Expectations Concordance and Stock Market Volatility: Knightian Uncertainty in the Year of the Pandemic

This study introduces a novel index based on expectations concordance for explaining stock-price volatility when historically unique events cause unforeseeable change and Knightian uncertainty in the process driving outcomes. Expectations concordance measures the degree to which nonrepetitive events are associated with directionally similar expectations of future returns. Narrative analytics of daily news reports allow for assessment of bullish versus bearish views in the stock market. Increases in expectations concordance across all KU events leads to reinforcing effects and an increase in stock market volatility. Lower expectations concordance produces a stabilizing effect wherein the offsetting views reduce market volatility. The empirical findings hold for ex post and ex ante measures of volatility and for OLS and GARCH estimates.

Assessing guideline-concordant care for patients with multimorbidity treated in a care management setting

Background Disease-specific guidelines are not aligned with multimorbidity care complexity. Meeting all guideline-recommended care for multimorbid patients has been estimated but not demonstrated across multiple guidelines. Objective Measure guideline-concordant care for patients with multimorbidity; assess in what types of care and by whom (clinician or patient) deviation from guidelines occurs and evaluate whether patient characteristics are associated with concordance. Methods A retrospective cohort study of care received over 1 year, conducted across 11 primary care clinics within the context of multimorbidity-focused care management program. Patients were aged 45+ years with more than two common chronic conditions and were sampled based on either being new (≤6 months) or veteran to the program (≥1 year). Measures Three guideline concordance measures were calculated for each patient out of 44 potential guideline-recommended care processes for nine chronic conditions: overall score; referral score (proportion of guideline-recommended care referred) and patient-only score (proportion of referred care completed by patients). Guideline concordance was stratified by care type. Results 4386 care processes evaluated among 204 patients, mean age = 72.3 years (standard deviation = 9.7). Overall, 79.2% of care was guideline concordant, 87.6% was referred according to guidelines and patients followed 91.4% of referred care. Guideline-concordant care varied across care types. Age, morbidity burden and whether patients were new or veteran to the program were associated with guideline concordance. Conclusions Patients with multimorbidity do not receive ~20% of guideline recommendations, mostly due to clinicians not referring care. Determining the types of care for which the greatest deviation from guidelines exists can inform the tailoring of care for multimorbidity patients.

Efficient and Accurate Evaluation Methods for Concordance Measures via Functional Tensor Characterizations of Copulas

There is now an increasingly large number of proposed concordance measures available to capture, measure and quantify different notions of dependence in stochastic processes. However, evaluation of concordance measures to quantify such types of dependence for different copula models can be challenging. In this work, we propose a class of new methods that involves a highly accurate and computationally efficient procedure to evaluate concordance measures for a given copula, applicable even when sampling from the copula is not easily achieved. In addition, this then allows us to reconstruct maps of concordance measures locally in all regions of the state space for any range of copula parameters. We believe this technique will be a valuable tool for practitioners to understand better the behaviour of copula models and associated concordance measures expressed in terms of these copula models.

Quantifying Donor Effects on Transplant Outcomes Using Kidney Pairs from Deceased Donors

Background and objectivesIn kidney transplantation, the relative contribution of donor versus other factors on clinical outcomes is unknown. We sought to quantify overall donor effects on transplant outcomes for kidney donations from deceased donors.Design, setting, participants, & measurementsFor paired donations from deceased donors resulting in transplants to different recipients, the magnitude of donor effects can be quantified by examining the excess of concordant outcomes within kidney pairs beyond chance concordance. Using data from the Organ Procurement and Transplantation Network between the years 2013 and 2017, we examined concordance measures for delayed graft function, death-censored 1-year graft failure, and death-censored 3-year graft failure. The concordance measures were excess relative risk, excess absolute risk, and the fixation index (where zero is no concordance and one is perfect concordance). We further examined concordance in strata of kidneys with similar values of the Kidney Donor Profile Index, a common metric of organ quality.ResultsIf the transplant of the kidney mate resulted in delayed graft function, risk for delayed graft function was 19% higher (95% confidence interval [95% CI], 18% to 20%), or 1.76-fold higher (95% CI, 1.73- to 1.80-fold), than baseline. If a kidney graft failed within 1 year, then the kidney mate’s risk of failure was 6% higher (95% CI, 4% to 9%), or 2.85-fold higher (95% CI, 2.25- to 3.48-fold), than baseline. For 3-year graft failure, the excess absolute risk was 7% (95% CI, 4% to 10%) but excess relative risk was smaller, 1.91-fold (95% CI, 1.56- to 2.28-fold). Fixation indices were 0.25 for delayed graft function (95% CI, 0.24 to 0.27), 0.07 for 1-year graft failure (95% CI, 0.04 to 0.09), and 0.07 for 3-year graft failure (95% CI, 0.04 to 0.10). Results were similar in strata of kidneys with a similar Kidney Donor Profile Index.ConclusionsOverall results indicated that the donor constitution has small or moderate effect on post-transplant clinical outcomes.