This paper provides a robust test of predictability under the predictive regression model with possible heavy-tailed innovations assumption,in which the predictive variable is persistent and its innovations are highly...This paper provides a robust test of predictability under the predictive regression model with possible heavy-tailed innovations assumption,in which the predictive variable is persistent and its innovations are highly correlated with returns.To this end,we propose a robust test which can capture empirical phenomena such as heavy tails,stationary,and local to unity.Moreover,we develop related asymptotic results without the second-moment assumption between the predictive variable and returns.To make the proposed test reasonable,we propose a generalized correlation and provide theoretical support.To illustrate the applicability of the test,we perform a simulation study for the impact of heavy-tailed innovations on predictability,as well as direct and/or indirect implementation of heavy-tailed innovations to predictability via the unit root phenomenon.Finally,we provide an empirical study for further illustration,to which the proposed test is applied to a U.S.equity data set.展开更多
BACKGROUND Minimally invasive surgery had been tailored to individual cases of gastric subepithelial tumors(SETs)after comparing the clinical outcomes of endoscopic resection(ER),laparoscopic resection(LR),and hybrid ...BACKGROUND Minimally invasive surgery had been tailored to individual cases of gastric subepithelial tumors(SETs)after comparing the clinical outcomes of endoscopic resection(ER),laparoscopic resection(LR),and hybrid methods.AIM To study the use of Goldilocks principle to determine the best form of minimally invasive surgery for gastric SETs.METHODS In this retrospective study,194 patients of gastric SETs with high probability of surgical intervention were included.All patients underwent tumor resection in the operating theater between January 2013 and December 2021.The patients were divided into two groups,ER or LR,according to the tumor characteristics and the initial intent of intervention.Few patients in the ER group required further backup laparoscopic surgery after an incomplete ER.The patients who had converted open surgery were excluded.A logistic regression model was used to assess the associations between patient characteristics and the likelihood of a treatment strategy.The area under the curve was used to assess the discriminative ability of tumor size and Youden’s index to determine the optimal cut-off tumor size.RESULTS One-hundred ninety-four patients(100 in the ER group and 94 in the LR group)underwent tumor resection in the operating theater.In the ER group,27 patients required backup laparoscopic surgery after an incomplete ER.The patients in the ER group had small tumor sizes and shorter procedure durations while the patients in the LR group had large tumor sizes,exophytic growth,malignancy,and tumors that were more often located in the middle or lower third of the stomach.Both groups had similar durations of hospital stays and a similar rate of major postoperative complications.The patients in the ER group who underwent backup surgery required longer procedures(56.4 min)and prolonged stays(2 d)compared to the patients in the LR group without the increased rate of major postoperative complications.The optimal cut-off point for the tumor size for laparoscopic surgery was 2.15 cm.CONCLUSION Multidisciplinary teamwork leads to the adoption of different strategies to yield efficient clinical outcomes according to the tumor characteristics.展开更多
基金The research of WONG Hsin-Chieh is partially supported by the NSTC(111-2118-M-305-004-MY2)the research of PANG Tian-xiao is partially supported by the National Social Science Foundation of China(21BTJ067)。
文摘This paper provides a robust test of predictability under the predictive regression model with possible heavy-tailed innovations assumption,in which the predictive variable is persistent and its innovations are highly correlated with returns.To this end,we propose a robust test which can capture empirical phenomena such as heavy tails,stationary,and local to unity.Moreover,we develop related asymptotic results without the second-moment assumption between the predictive variable and returns.To make the proposed test reasonable,we propose a generalized correlation and provide theoretical support.To illustrate the applicability of the test,we perform a simulation study for the impact of heavy-tailed innovations on predictability,as well as direct and/or indirect implementation of heavy-tailed innovations to predictability via the unit root phenomenon.Finally,we provide an empirical study for further illustration,to which the proposed test is applied to a U.S.equity data set.
基金The study was approved by the Institutional Review Board of Changhua Christian Hospital(approval No.220117).
文摘BACKGROUND Minimally invasive surgery had been tailored to individual cases of gastric subepithelial tumors(SETs)after comparing the clinical outcomes of endoscopic resection(ER),laparoscopic resection(LR),and hybrid methods.AIM To study the use of Goldilocks principle to determine the best form of minimally invasive surgery for gastric SETs.METHODS In this retrospective study,194 patients of gastric SETs with high probability of surgical intervention were included.All patients underwent tumor resection in the operating theater between January 2013 and December 2021.The patients were divided into two groups,ER or LR,according to the tumor characteristics and the initial intent of intervention.Few patients in the ER group required further backup laparoscopic surgery after an incomplete ER.The patients who had converted open surgery were excluded.A logistic regression model was used to assess the associations between patient characteristics and the likelihood of a treatment strategy.The area under the curve was used to assess the discriminative ability of tumor size and Youden’s index to determine the optimal cut-off tumor size.RESULTS One-hundred ninety-four patients(100 in the ER group and 94 in the LR group)underwent tumor resection in the operating theater.In the ER group,27 patients required backup laparoscopic surgery after an incomplete ER.The patients in the ER group had small tumor sizes and shorter procedure durations while the patients in the LR group had large tumor sizes,exophytic growth,malignancy,and tumors that were more often located in the middle or lower third of the stomach.Both groups had similar durations of hospital stays and a similar rate of major postoperative complications.The patients in the ER group who underwent backup surgery required longer procedures(56.4 min)and prolonged stays(2 d)compared to the patients in the LR group without the increased rate of major postoperative complications.The optimal cut-off point for the tumor size for laparoscopic surgery was 2.15 cm.CONCLUSION Multidisciplinary teamwork leads to the adoption of different strategies to yield efficient clinical outcomes according to the tumor characteristics.
