BACKGROUND The log odds of positive lymph nodes(LODDS)are correlated with survival outcomes in gastric cancer(GC)patients.However,the prognostic value across different tumor differentiation levels remains unclear.AIM ...BACKGROUND The log odds of positive lymph nodes(LODDS)are correlated with survival outcomes in gastric cancer(GC)patients.However,the prognostic value across different tumor differentiation levels remains unclear.AIM To evaluate the independent prognostic value of LODDS and the stratified predictive efficacy in GC patients with different histologic differentiations.METHODS We conducted a retrospective analysis of 2103 GC patients who underwent radical gastrectomy at Zhejiang Cancer Hospital.The prognostic value of LODDS was compared with that of other lymph node-based metrics,including the pathologic N stage,number of positive lymph nodes,number of total lymph nodes,and lymph node ratio,stratified by tumor differentiation.RESULTS LODDS was identified as an independent prognostic factor for overall survival in moderately to poorly differentiated GC patients.LODDS demonstrated superior predictive accuracy over other lymph node metrics.A nomogram incorporating LODDS,age,carbohydrate antigen(CA)125,carcinoembryonic antigen,and tumor differentiation showed good predictive accuracy(C-index=0.703).A higher LODDS was significantly associated with an increased risk of recurrence or metastasis,poorly differentiated tumors,advanced cancer,mucinous gastric adenocarcinoma,nerve invasion,and vascular tumor thrombus.Additionally,LODDS was positively correlated with the tumor markers CA19-9,CA72-4,CA125,and CA242(all P<0.05).CONCLUSION LODDS is an independent prognostic indicator for patients with moderately and poorly differentiated GC,and its predictive performance is superior to that of other models.展开更多
Objective: To explore the prognostic value of log odds of positive lymph nodes (LODDS) in patients with gastroenteropancreatic neuroendocrine tumors (GEPNET) and to develop nomograms based on LODDS for predicting 1-ye...Objective: To explore the prognostic value of log odds of positive lymph nodes (LODDS) in patients with gastroenteropancreatic neuroendocrine tumors (GEPNET) and to develop nomograms based on LODDS for predicting 1-year, 3-year, and 5-year overall survival (OS) and cancer-specific survival (CSS). Methods: This retrospective cohort study was based on the Surveillance, Epidemiology, and End Results (SEER) Program. Demographic data, clinical data, and survival status were extracted, with endpoints of OS and CSS. Multivariate Cox proportional hazards regression analysis assessed predictors associated with OS and CSS, with hazard ratios (HRs) and 95% confidence intervals (CIs) evaluated. Nomogram performance was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC). Results: A total of 1,673 patients were included and divided into a training set (n = 1,172) and a testing set (n = 501). Multivariate Cox proportional hazards regression analyses identified LODDS as an independent prognostic factor for OS (HR = 1.79, 95% CI: 1.44-2.24) and CSS (HR = 1.81, 95% CI: 1.41-2.31). The OS and CSS nomograms, developed from multivariate Cox regression analyses, showed good performance, with AUCs of 0.858, 0.878, and 0.852 for predicting 1-year, 3-year, and 5-year OS, and AUCs of 0.859, 0.887, and 0.865 for 1-year, 3-year, and 5-year CSS in the testing set. The nomograms are accessible online (OS: https://zhmte.shinyapps.io/DynNomapp/;CSS: https:// zhmty.shinyapps.io/DynNomapp/). Conclusions: LODDS serves as an independent prognostic factor in GEPNET. Online nomograms based on LODDS demonstrated effective performance in predicting OS and CSS in GEPNET patients, providing a convenient tool for clinical application.展开更多
Objective: Our aims were to establish novel nomogram models, which directly targeted patients with signet ring cell carcinoma(SRC), for individualized prediction of overall survival(OS) rate and cancer-specific surviv...Objective: Our aims were to establish novel nomogram models, which directly targeted patients with signet ring cell carcinoma(SRC), for individualized prediction of overall survival(OS) rate and cancer-specific survival(CSS).Methods: We selected 1,365 SRC patients diagnosed from 2010 to 2015 from Surveillance, Epidemiology and End Results(SEER) database, and then randomly partitioned them into a training cohort and a validation cohort.Independent predicted indicators, which were identified by using univariate testing and multivariate analyses, were used to construct our prognostic nomogram models. Three methods, Harrell concordance index(C-index), receiver operating characteristics(ROC) curve and calibration curve, were used to assess the ability of discrimination and predictive accuracy. Integrated discrimination improvement(IDI), net reclassification improvement(NRI) and decision curve analysis(DCA) were used to assess clinical utility of our nomogram models.Results: Six independent predicted indicators, age, race, log odds of positive lymph nodes(LODDS), T stage, M stage and tumor size, were associated with OS rate. Nevertheless, only five independent predicted indicators were associated with CSS except race. The developed nomograms based on those independent predicted factors showed reliable discrimination. C-index of our nomogram for OS and CSS was 0.760 and 0.763, which were higher than American Joint Committee on Cancer(AJCC) 8 th edition tumor-node-metastasis(TNM) staging system(0.734 and 0.741, respectively). C-index of validation cohort for OS was 0.757 and for CSS was 0.773. The calibration curves also performed good consistency. IDI, NRI and DCA showed the nomograms for both OS and CSS had a comparable clinical utility than the TNM staging system.Conclusions: The novel nomogram models based on LODDS provided satisfying predictive ability of SRC both in OS and CSS than AJCC 8 th edition TNM staging system alone.展开更多
The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented. The defined equivalent test plan is the test plan that has the same...The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented. The defined equivalent test plan is the test plan that has the same value of the determinant of Fisher information matrix. The equivalent test plan of step stress accelerated life testing （SSALT） to a baseline optimum constant stress accelerated life testing （CSALT） plan is obtained by adjusting the censoring time of SSALT and solving the optimization problem for each case to achieve the same value of the determinant of Fisher information matrix as in the baseline optimum CSALT plan. Numer- ical examples are given finally which demonstrate the equivalent SSALT plan to the baseline optimum CSALT plan reduces almost half of the test time while achieving approximately the same estimation errors of model parameters.展开更多
An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path- free and distribution-free properties, avoiding the errors caused by faulty assumptions of degrad...An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path- free and distribution-free properties, avoiding the errors caused by faulty assumptions of degradation paths or distribution of degra- dation measurements. It is established based on a link function which combines the degradation cumulative hazard rate function and the degradation odds function through a transformation pa- rameter, and this makes the accelerated proportional degradation hazards model and the accelerated proportional degradation odds model special cases of it. Hypothesis tests are discussed, and the proposed model is applicable when some model assumptions are satisfied. This model is utilized to estimate the reliability of minia- ture bulbs under low stress levels based on the degradation data obtained under high stress levels to validate the effectiveness of this model.展开更多
BACKGROUND Signet ring cell carcinoma is a rare type of oesophageal cancer,and we hypothesized that log odds of positive lymph nodes(LODDS)is a better prognostic factor for oesophageal signet ring cell carcinoma.AIM T...BACKGROUND Signet ring cell carcinoma is a rare type of oesophageal cancer,and we hypothesized that log odds of positive lymph nodes(LODDS)is a better prognostic factor for oesophageal signet ring cell carcinoma.AIM To explore a novel prognostic factor for oesophageal signet ring cell carcinoma by comparing two lymph node-related prognostic factors,log odds of positive LODDS and N stage.METHODS A total of 259 cases of oesophageal signet ring cell carcinoma after oesophagectomy were obtained from the Surveillance,Epidemiology,and End Results database between 2006 and 2016.The prognostic value of LODDS and N stage for oesophageal signet ring cell carcinoma was evaluated by univariate and multivariate analyses.The Akaike information criterion and Harrell’s C-index were used to assess the value of two prediction models based on lymph nodes.External validation was performed to further confirm the conclusion.RESULTS The 5-year cancer-specific survival(CSS)and 5-year overall survival(OS)rates of all the cases were 41.3%and 27.0%,respectively.The Kaplan-Meier method showed that LODDS had a higher score of log rank chi-squared(OS:46.162,CSS:41.178)than N stage(OS:36.215,CSS:31.583).Univariate analyses showed that insurance,race,T stage,M stage,TNM stage,radiation therapy,N stage,and LODDS were potential prognostic factors for OS(P<0.1).The multivariate Cox regression model showed that LODDS was an significant independent prognostic factor for oesophageal signet ring carcinoma patients after surgical resection(P<0.05),while N stage was not considered to be a significant prognostic factor(P=0.122).Model 2(LODDS)had a higher degree of discrimination and fit than Model 1(N stage)(LODDS vs N stage,Harell’s C-index 0.673 vs 0.656,P<0.001;Akaike information criterion 1688.824 vs 1697.519,P<0.001).The results of external validation were consistent with those in the study cohort.CONCLUSION LODDS is a superior prognostic factor to N stage for patients with oesophageal signet ring cell carcinoma after oesophagectomy.展开更多
BACKGROUND Colon cancer(CC)is one of the most common cancers of the digestive tract,the third most common cancer worldwide,and the second most common cause of cancer-related deaths.Previous studies have demonstrated a...BACKGROUND Colon cancer(CC)is one of the most common cancers of the digestive tract,the third most common cancer worldwide,and the second most common cause of cancer-related deaths.Previous studies have demonstrated a higher risk of lymph node metastasis(LNM)in young patients with CC.It might be reasonable to treat patients with early-onset locally advanced CC with extended lymph node dissection.However,few studies have focused on early-onset CC(ECC)patients with LNM.At present,the methods of predicting and evaluating the prognosis of ECC patients with LNM are controversial.From the data of patients with CC obtained from the Surveillance,Epidemiology,and End Results(SEER)database,data of young patients with ECC(≤50 years old)was screened.Patients with unknown data were excluded from the study,while the remaining patients were included.The patients were randomly divided into a training group(train)and a testing group(test)in the ratio of 7:3,while building the model.The model was constructed by the training group and verified by the testing group.Using multiple Cox regression models to compare the prediction efficiency of LNM indicators,nomograms were built based on the best model selected for overall survival(OS)and cause-specific survival(CSS).In the two groups,the performance of the nomogram was evaluated by constructing a calibration plot,time-dependent area under the curve(AUC),and decision curve analysis.Finally,the patients were grouped based on the risk score predicted by the prognosis model,and the survival curve was constructed after comparing the survival status of the high and low-risk groups.RESULTS Records of 26922 ECC patients were screened from the SEER database.N classification,positive lymph nodes(PLN),lymph node ratio(LNR)and log odds of PLN(LODDS)were considered to be independent predictors of OS and CSS.In addition,independent risk factors for OS included gender,race,marital status,primary site,histology,grade,T,and M classification,while the independent prognostic factors for CSS included race,marital status,primary site,grade,T,and M classification.The prediction model including LODDS is composed of minimal Akaike information criterion,maximal concordance indexes,and AUCs.Factors including gender,race,marital status,primary site,histology,grade,T,M classification,and LODDS were integrated into the OS nomogram,while race,marital status,primary site,grade,T,M classification,and LODDS were included into the CSS nomogram.The nomogram representing both cohorts had been successfully verified in terms of prediction accuracy and clinical practicability.CONCLUSION LODDS is superior to N-stage,PLN,and LNR of ECC.The nomogram containing LODDS might be helpful in tumor evaluation and clinical decision-making,since it provides an appropriate prediction of ECC.展开更多
The sign of an association measure between two varibles may be strongly affected and even be reversed after marginalization over a backgruoud variable, which is the well-known Yule-Simpson paradox.Odds ratios are stro...The sign of an association measure between two varibles may be strongly affected and even be reversed after marginalization over a backgruoud variable, which is the well-known Yule-Simpson paradox.Odds ratios are strongly collapsible over a background variable if they remain unchanged no matter how the background variable is partially pooled.In this paper, we firstly give some definitions and notations about odds ratios between a dichotomous explanatory variable and a continuous response variable.Then, we present conditions for simple collapsibility of odds ratios.Further, necessary and sufficient conditions are given for strong collapsibility of odds ratios for continuous outcome variable.展开更多
The purpose of this paper is to bring awareness to the general public that certain conditions that occur at a buoy in the Atlantic Basin, such as wind located at the buoy, pressure located at a buoy, water temperature...The purpose of this paper is to bring awareness to the general public that certain conditions that occur at a buoy in the Atlantic Basin, such as wind located at the buoy, pressure located at a buoy, water temperature located at a buoy, atmospheric pressure located at a buoy, may be useful in helping predict when a hurricane could possibly hit the state of Florida in the future. One of the goals of this paper is to bring new statistical methods to investigate and analyze data, which will create better predicable measures in determining when a hurricane will possibly hit the state of Florida. In this paper, the topics of binary logistic regression and multinomial regression modeling are discussed in reference to their outcomes of both the odds ratio and relative risk ratio respectively. The coefficients from these models will show which prospective buoy conditions are possibly more responsible for indication of a storm being present in the Atlantic Basin. In this paper, the data that was used and compiled into a larger data set came from two different sources. First, the hurricane data for the years 1992-2013 came from Unisys Weather site (Atlantic Basin Hurricanes data) and the buoy data has been available from the National Buoy Center. In this paper, the variables of interest are: storm present, buoy wind speed, buoy pressure, buoy atmospheric temperature, buoy water temperature and buoy wind direction. The buoy conditions are the buoy wind, the buoy wind direction, the buoy pressure, buoy atmospheric temperature and the buoy water temperature.展开更多
There are a few statistics testing the homogeneity of odds ratios across strata. Asymptotic statistics lose their power in the “sparse-data” setting. Both asymptotic statistics and exact tests have low power when th...There are a few statistics testing the homogeneity of odds ratios across strata. Asymptotic statistics lose their power in the “sparse-data” setting. Both asymptotic statistics and exact tests have low power when the sample sizes are small. We created a set of U statistics and compared them with some existing statistics in testing homogeneity of OR at different data settings. We evaluated their performance in terms of the empirical size and power via Monto Carlo simulations. Our results showed that two of the U-statistics under our study had higher power for testing homogeneity of odds ratios for 2 by 2 contingency tables. The application of the tests was illustrated in two real examples.展开更多
The media are constantly evolving at a breakneck pace and mainly young people, with their flexibility of mind and their continuous curiosity, can better understand the characteristics and potential of such advances. T...The media are constantly evolving at a breakneck pace and mainly young people, with their flexibility of mind and their continuous curiosity, can better understand the characteristics and potential of such advances. The aim of this paper is to analyze the relationship between teenagers and media, in order to try to better understand the habits and to conduct analysis on social interactions with young people. In order to evaluate the influence of mass media in the life of the young people, the Statisticians of Messina University decided to perform a statistical survey to evaluate the influence of the media in the life of Messina＇s teenagers. A questionnaire entitled ＂Perceptions of the influence exerted by mass media＂ was administered in some schools. From the methodological point of view, three statistical models were estimated in order to formalize the dependence of the mass media influence by the kind of TV programs, the time spent on TV viewing and computer use and the kind of most used social networks. Since the mass media influence is an ordinal variable expressed by four ordered categories （1 = nothing; 2 = low; 3 = average; 4 = high） we used the Cumulative Proportional Odds Model to formalize the dependence by the potential predictors.展开更多
Despite low traffic in Wyoming,pedestrian crash severity accounts for a high number of fatalities in the state.Thus this study was conducted to highlights factors contributing to those crashes.The results highlighted ...Despite low traffic in Wyoming,pedestrian crash severity accounts for a high number of fatalities in the state.Thus this study was conducted to highlights factors contributing to those crashes.The results highlighted that drivers under influence,type of vehicle,location of crashes,estimated speed of vehicles,driving over the recommended speed are some of factors contributing to the severity of crashes.In this study,we used proportional odds model which assumes that the impact of each attribute is consistent or proportional across various threshold values.However,it has been argued that this assumption might be unrealistic,especially at the presence of extreme values.Thus,the assumption was relaxed in this study by shifting the thresholds based on some explanatory attributes,or proportional odds effects.In addition,we accounted for the spread rate,or scale,of the model’s latent distribution of pedestrian crashes.The results highlighted that the partial proportional odds model through proportional odds factor and scale effects result in a significant improvement in model fit compared with the standard proportional odds model.Comparisons were also made across standard normal,simple partial ordinal model,and partial ordinal accounting for scale heterogeneity.In addition,various potential threshold structures such as symmetric and flexible were considered,but similar goodness of fits were observed across all those models.Extensive discussion has been made regarding the formulation of the implemented methodology,and its implications.展开更多
BACKGROUND Lymph node status is a critical prognostic factor in gastric cancer(GC),but stage migration may occur in pathological lymph nodes(pN)staging.To address this,alternative staging systems such as the positive ...BACKGROUND Lymph node status is a critical prognostic factor in gastric cancer(GC),but stage migration may occur in pathological lymph nodes(pN)staging.To address this,alternative staging systems such as the positive lymph node ratio(LNR)and log odds of positive lymph nodes(LODDS)were introduced.AIM To assess the prognostic accuracy and stratification efficacy of three nodal staging systems in GC.METHODS A systematic review identified 12 studies,from which hazard ratios(HRs)for overall survival(OS)were summarized.Sensitivity analyses,subgroup analyses,publication bias assessments,and quality evaluations were conducted.To enhance comparability,data from studies with identical cutoff values for pN,LNR,and LODDS were pooled.Homogeneous stratification was then applied to generate Kaplan-Meier(KM)survival curves,assessing the stratification efficacy of three staging systems.RESULTS The HRs and 95%confidence intervals for pN,LNR,and LODDS were 2.16(1.72-2.73),2.05(1.65-2.55),and 3.15(2.15-4.37),respectively,confirming all three as independent prognostic risk factors for OS.Comparative analysis of HRs demonstrated that LODDS had superior prognostic predictive power over LNR and pN.KM curves for pN(N0,N1,N2,N3a,N3b),LNR(0.1/0.2/0.5),and LODDS(-1.5/-1.0/-0.5/0)revealed significant differences(P<0.001)among all prognostic stratifications.Mean differences and standard deviations in 60-month relative survival were 27.93%±0.29%,41.70%±0.30%,and 26.60%±0.28%for pN,LNR,and LODDS,respectively.CONCLUSION All three staging systems are independent prognostic factors for OS.LODDS demonstrated the highest specificity,making it especially useful for predicting outcomes,while pN was the most effective in homogeneous stratification,offering better patient differentiation.These findings highlight the complementary roles of LODDS and pN in enhancing prognostic accuracy and stratification.展开更多
In this paper,we give a complete characterization of all self-adjoint domains of odd order differential operators on two intervals.These two intervals with all four endpoints are singular(one endpoint of each interval...In this paper,we give a complete characterization of all self-adjoint domains of odd order differential operators on two intervals.These two intervals with all four endpoints are singular(one endpoint of each interval is singular or all four endpoints are regulars are the special cases).And these extensions yield"new"self-adjoint operators,which involve interactions between the two intervals.展开更多
基金Supported by the National Natural Science Foundation of China,No.82473195 and No.32370797the Natural Science Foundation of Zhejiang Province,No.LTGY23H160018+3 种基金the Zhejiang Medical and Health Science and Technology Program,No.2024KY789 and No.2023KY615the National Research Center for Translational Medicine at Shanghai Program,No.NRCTM(SH)-2025-07the Beijing Science and Technology Innovation Medical Development Foundation,No.KC2023-JX-0270-07the Key Laboratory of Prevention,Diagnosis and Therapy of Upper Gastrointestinal Cancer of Zhejiang Province,No.2022E10021.
文摘BACKGROUND The log odds of positive lymph nodes(LODDS)are correlated with survival outcomes in gastric cancer(GC)patients.However,the prognostic value across different tumor differentiation levels remains unclear.AIM To evaluate the independent prognostic value of LODDS and the stratified predictive efficacy in GC patients with different histologic differentiations.METHODS We conducted a retrospective analysis of 2103 GC patients who underwent radical gastrectomy at Zhejiang Cancer Hospital.The prognostic value of LODDS was compared with that of other lymph node-based metrics,including the pathologic N stage,number of positive lymph nodes,number of total lymph nodes,and lymph node ratio,stratified by tumor differentiation.RESULTS LODDS was identified as an independent prognostic factor for overall survival in moderately to poorly differentiated GC patients.LODDS demonstrated superior predictive accuracy over other lymph node metrics.A nomogram incorporating LODDS,age,carbohydrate antigen(CA)125,carcinoembryonic antigen,and tumor differentiation showed good predictive accuracy(C-index=0.703).A higher LODDS was significantly associated with an increased risk of recurrence or metastasis,poorly differentiated tumors,advanced cancer,mucinous gastric adenocarcinoma,nerve invasion,and vascular tumor thrombus.Additionally,LODDS was positively correlated with the tumor markers CA19-9,CA72-4,CA125,and CA242(all P<0.05).CONCLUSION LODDS is an independent prognostic indicator for patients with moderately and poorly differentiated GC,and its predictive performance is superior to that of other models.
文摘Objective: To explore the prognostic value of log odds of positive lymph nodes (LODDS) in patients with gastroenteropancreatic neuroendocrine tumors (GEPNET) and to develop nomograms based on LODDS for predicting 1-year, 3-year, and 5-year overall survival (OS) and cancer-specific survival (CSS). Methods: This retrospective cohort study was based on the Surveillance, Epidemiology, and End Results (SEER) Program. Demographic data, clinical data, and survival status were extracted, with endpoints of OS and CSS. Multivariate Cox proportional hazards regression analysis assessed predictors associated with OS and CSS, with hazard ratios (HRs) and 95% confidence intervals (CIs) evaluated. Nomogram performance was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC). Results: A total of 1,673 patients were included and divided into a training set (n = 1,172) and a testing set (n = 501). Multivariate Cox proportional hazards regression analyses identified LODDS as an independent prognostic factor for OS (HR = 1.79, 95% CI: 1.44-2.24) and CSS (HR = 1.81, 95% CI: 1.41-2.31). The OS and CSS nomograms, developed from multivariate Cox regression analyses, showed good performance, with AUCs of 0.858, 0.878, and 0.852 for predicting 1-year, 3-year, and 5-year OS, and AUCs of 0.859, 0.887, and 0.865 for 1-year, 3-year, and 5-year CSS in the testing set. The nomograms are accessible online (OS: https://zhmte.shinyapps.io/DynNomapp/;CSS: https:// zhmty.shinyapps.io/DynNomapp/). Conclusions: LODDS serves as an independent prognostic factor in GEPNET. Online nomograms based on LODDS demonstrated effective performance in predicting OS and CSS in GEPNET patients, providing a convenient tool for clinical application.
文摘Objective: Our aims were to establish novel nomogram models, which directly targeted patients with signet ring cell carcinoma(SRC), for individualized prediction of overall survival(OS) rate and cancer-specific survival(CSS).Methods: We selected 1,365 SRC patients diagnosed from 2010 to 2015 from Surveillance, Epidemiology and End Results(SEER) database, and then randomly partitioned them into a training cohort and a validation cohort.Independent predicted indicators, which were identified by using univariate testing and multivariate analyses, were used to construct our prognostic nomogram models. Three methods, Harrell concordance index(C-index), receiver operating characteristics(ROC) curve and calibration curve, were used to assess the ability of discrimination and predictive accuracy. Integrated discrimination improvement(IDI), net reclassification improvement(NRI) and decision curve analysis(DCA) were used to assess clinical utility of our nomogram models.Results: Six independent predicted indicators, age, race, log odds of positive lymph nodes(LODDS), T stage, M stage and tumor size, were associated with OS rate. Nevertheless, only five independent predicted indicators were associated with CSS except race. The developed nomograms based on those independent predicted factors showed reliable discrimination. C-index of our nomogram for OS and CSS was 0.760 and 0.763, which were higher than American Joint Committee on Cancer(AJCC) 8 th edition tumor-node-metastasis(TNM) staging system(0.734 and 0.741, respectively). C-index of validation cohort for OS was 0.757 and for CSS was 0.773. The calibration curves also performed good consistency. IDI, NRI and DCA showed the nomograms for both OS and CSS had a comparable clinical utility than the TNM staging system.Conclusions: The novel nomogram models based on LODDS provided satisfying predictive ability of SRC both in OS and CSS than AJCC 8 th edition TNM staging system alone.
文摘The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented. The defined equivalent test plan is the test plan that has the same value of the determinant of Fisher information matrix. The equivalent test plan of step stress accelerated life testing （SSALT） to a baseline optimum constant stress accelerated life testing （CSALT） plan is obtained by adjusting the censoring time of SSALT and solving the optimization problem for each case to achieve the same value of the determinant of Fisher information matrix as in the baseline optimum CSALT plan. Numer- ical examples are given finally which demonstrate the equivalent SSALT plan to the baseline optimum CSALT plan reduces almost half of the test time while achieving approximately the same estimation errors of model parameters.
基金supported by the postdoctoral funding at Tsinghua University
文摘An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path- free and distribution-free properties, avoiding the errors caused by faulty assumptions of degradation paths or distribution of degra- dation measurements. It is established based on a link function which combines the degradation cumulative hazard rate function and the degradation odds function through a transformation pa- rameter, and this makes the accelerated proportional degradation hazards model and the accelerated proportional degradation odds model special cases of it. Hypothesis tests are discussed, and the proposed model is applicable when some model assumptions are satisfied. This model is utilized to estimate the reliability of minia- ture bulbs under low stress levels based on the degradation data obtained under high stress levels to validate the effectiveness of this model.
基金Capital Health Development Research Project,No.2014-1-4021.
文摘BACKGROUND Signet ring cell carcinoma is a rare type of oesophageal cancer,and we hypothesized that log odds of positive lymph nodes(LODDS)is a better prognostic factor for oesophageal signet ring cell carcinoma.AIM To explore a novel prognostic factor for oesophageal signet ring cell carcinoma by comparing two lymph node-related prognostic factors,log odds of positive LODDS and N stage.METHODS A total of 259 cases of oesophageal signet ring cell carcinoma after oesophagectomy were obtained from the Surveillance,Epidemiology,and End Results database between 2006 and 2016.The prognostic value of LODDS and N stage for oesophageal signet ring cell carcinoma was evaluated by univariate and multivariate analyses.The Akaike information criterion and Harrell’s C-index were used to assess the value of two prediction models based on lymph nodes.External validation was performed to further confirm the conclusion.RESULTS The 5-year cancer-specific survival(CSS)and 5-year overall survival(OS)rates of all the cases were 41.3%and 27.0%,respectively.The Kaplan-Meier method showed that LODDS had a higher score of log rank chi-squared(OS:46.162,CSS:41.178)than N stage(OS:36.215,CSS:31.583).Univariate analyses showed that insurance,race,T stage,M stage,TNM stage,radiation therapy,N stage,and LODDS were potential prognostic factors for OS(P<0.1).The multivariate Cox regression model showed that LODDS was an significant independent prognostic factor for oesophageal signet ring carcinoma patients after surgical resection(P<0.05),while N stage was not considered to be a significant prognostic factor(P=0.122).Model 2(LODDS)had a higher degree of discrimination and fit than Model 1(N stage)(LODDS vs N stage,Harell’s C-index 0.673 vs 0.656,P<0.001;Akaike information criterion 1688.824 vs 1697.519,P<0.001).The results of external validation were consistent with those in the study cohort.CONCLUSION LODDS is a superior prognostic factor to N stage for patients with oesophageal signet ring cell carcinoma after oesophagectomy.
文摘BACKGROUND Colon cancer(CC)is one of the most common cancers of the digestive tract,the third most common cancer worldwide,and the second most common cause of cancer-related deaths.Previous studies have demonstrated a higher risk of lymph node metastasis(LNM)in young patients with CC.It might be reasonable to treat patients with early-onset locally advanced CC with extended lymph node dissection.However,few studies have focused on early-onset CC(ECC)patients with LNM.At present,the methods of predicting and evaluating the prognosis of ECC patients with LNM are controversial.From the data of patients with CC obtained from the Surveillance,Epidemiology,and End Results(SEER)database,data of young patients with ECC(≤50 years old)was screened.Patients with unknown data were excluded from the study,while the remaining patients were included.The patients were randomly divided into a training group(train)and a testing group(test)in the ratio of 7:3,while building the model.The model was constructed by the training group and verified by the testing group.Using multiple Cox regression models to compare the prediction efficiency of LNM indicators,nomograms were built based on the best model selected for overall survival(OS)and cause-specific survival(CSS).In the two groups,the performance of the nomogram was evaluated by constructing a calibration plot,time-dependent area under the curve(AUC),and decision curve analysis.Finally,the patients were grouped based on the risk score predicted by the prognosis model,and the survival curve was constructed after comparing the survival status of the high and low-risk groups.RESULTS Records of 26922 ECC patients were screened from the SEER database.N classification,positive lymph nodes(PLN),lymph node ratio(LNR)and log odds of PLN(LODDS)were considered to be independent predictors of OS and CSS.In addition,independent risk factors for OS included gender,race,marital status,primary site,histology,grade,T,and M classification,while the independent prognostic factors for CSS included race,marital status,primary site,grade,T,and M classification.The prediction model including LODDS is composed of minimal Akaike information criterion,maximal concordance indexes,and AUCs.Factors including gender,race,marital status,primary site,histology,grade,T,M classification,and LODDS were integrated into the OS nomogram,while race,marital status,primary site,grade,T,M classification,and LODDS were included into the CSS nomogram.The nomogram representing both cohorts had been successfully verified in terms of prediction accuracy and clinical practicability.CONCLUSION LODDS is superior to N-stage,PLN,and LNR of ECC.The nomogram containing LODDS might be helpful in tumor evaluation and clinical decision-making,since it provides an appropriate prediction of ECC.
基金Funded by Fundamental Research Funds for the Central Universities (Grant No.BUPT2012RC0708)
文摘The sign of an association measure between two varibles may be strongly affected and even be reversed after marginalization over a backgruoud variable, which is the well-known Yule-Simpson paradox.Odds ratios are strongly collapsible over a background variable if they remain unchanged no matter how the background variable is partially pooled.In this paper, we firstly give some definitions and notations about odds ratios between a dichotomous explanatory variable and a continuous response variable.Then, we present conditions for simple collapsibility of odds ratios.Further, necessary and sufficient conditions are given for strong collapsibility of odds ratios for continuous outcome variable.
文摘The purpose of this paper is to bring awareness to the general public that certain conditions that occur at a buoy in the Atlantic Basin, such as wind located at the buoy, pressure located at a buoy, water temperature located at a buoy, atmospheric pressure located at a buoy, may be useful in helping predict when a hurricane could possibly hit the state of Florida in the future. One of the goals of this paper is to bring new statistical methods to investigate and analyze data, which will create better predicable measures in determining when a hurricane will possibly hit the state of Florida. In this paper, the topics of binary logistic regression and multinomial regression modeling are discussed in reference to their outcomes of both the odds ratio and relative risk ratio respectively. The coefficients from these models will show which prospective buoy conditions are possibly more responsible for indication of a storm being present in the Atlantic Basin. In this paper, the data that was used and compiled into a larger data set came from two different sources. First, the hurricane data for the years 1992-2013 came from Unisys Weather site (Atlantic Basin Hurricanes data) and the buoy data has been available from the National Buoy Center. In this paper, the variables of interest are: storm present, buoy wind speed, buoy pressure, buoy atmospheric temperature, buoy water temperature and buoy wind direction. The buoy conditions are the buoy wind, the buoy wind direction, the buoy pressure, buoy atmospheric temperature and the buoy water temperature.
文摘There are a few statistics testing the homogeneity of odds ratios across strata. Asymptotic statistics lose their power in the “sparse-data” setting. Both asymptotic statistics and exact tests have low power when the sample sizes are small. We created a set of U statistics and compared them with some existing statistics in testing homogeneity of OR at different data settings. We evaluated their performance in terms of the empirical size and power via Monto Carlo simulations. Our results showed that two of the U-statistics under our study had higher power for testing homogeneity of odds ratios for 2 by 2 contingency tables. The application of the tests was illustrated in two real examples.
文摘The media are constantly evolving at a breakneck pace and mainly young people, with their flexibility of mind and their continuous curiosity, can better understand the characteristics and potential of such advances. The aim of this paper is to analyze the relationship between teenagers and media, in order to try to better understand the habits and to conduct analysis on social interactions with young people. In order to evaluate the influence of mass media in the life of the young people, the Statisticians of Messina University decided to perform a statistical survey to evaluate the influence of the media in the life of Messina＇s teenagers. A questionnaire entitled ＂Perceptions of the influence exerted by mass media＂ was administered in some schools. From the methodological point of view, three statistical models were estimated in order to formalize the dependence of the mass media influence by the kind of TV programs, the time spent on TV viewing and computer use and the kind of most used social networks. Since the mass media influence is an ordinal variable expressed by four ordered categories （1 = nothing; 2 = low; 3 = average; 4 = high） we used the Cumulative Proportional Odds Model to formalize the dependence by the potential predictors.
文摘Despite low traffic in Wyoming,pedestrian crash severity accounts for a high number of fatalities in the state.Thus this study was conducted to highlights factors contributing to those crashes.The results highlighted that drivers under influence,type of vehicle,location of crashes,estimated speed of vehicles,driving over the recommended speed are some of factors contributing to the severity of crashes.In this study,we used proportional odds model which assumes that the impact of each attribute is consistent or proportional across various threshold values.However,it has been argued that this assumption might be unrealistic,especially at the presence of extreme values.Thus,the assumption was relaxed in this study by shifting the thresholds based on some explanatory attributes,or proportional odds effects.In addition,we accounted for the spread rate,or scale,of the model’s latent distribution of pedestrian crashes.The results highlighted that the partial proportional odds model through proportional odds factor and scale effects result in a significant improvement in model fit compared with the standard proportional odds model.Comparisons were also made across standard normal,simple partial ordinal model,and partial ordinal accounting for scale heterogeneity.In addition,various potential threshold structures such as symmetric and flexible were considered,but similar goodness of fits were observed across all those models.Extensive discussion has been made regarding the formulation of the implemented methodology,and its implications.
基金the Clinical Medical Team Introduction Program of Suzhou,No.SZYJTD201804.
文摘BACKGROUND Lymph node status is a critical prognostic factor in gastric cancer(GC),but stage migration may occur in pathological lymph nodes(pN)staging.To address this,alternative staging systems such as the positive lymph node ratio(LNR)and log odds of positive lymph nodes(LODDS)were introduced.AIM To assess the prognostic accuracy and stratification efficacy of three nodal staging systems in GC.METHODS A systematic review identified 12 studies,from which hazard ratios(HRs)for overall survival(OS)were summarized.Sensitivity analyses,subgroup analyses,publication bias assessments,and quality evaluations were conducted.To enhance comparability,data from studies with identical cutoff values for pN,LNR,and LODDS were pooled.Homogeneous stratification was then applied to generate Kaplan-Meier(KM)survival curves,assessing the stratification efficacy of three staging systems.RESULTS The HRs and 95%confidence intervals for pN,LNR,and LODDS were 2.16(1.72-2.73),2.05(1.65-2.55),and 3.15(2.15-4.37),respectively,confirming all three as independent prognostic risk factors for OS.Comparative analysis of HRs demonstrated that LODDS had superior prognostic predictive power over LNR and pN.KM curves for pN(N0,N1,N2,N3a,N3b),LNR(0.1/0.2/0.5),and LODDS(-1.5/-1.0/-0.5/0)revealed significant differences(P<0.001)among all prognostic stratifications.Mean differences and standard deviations in 60-month relative survival were 27.93%±0.29%,41.70%±0.30%,and 26.60%±0.28%for pN,LNR,and LODDS,respectively.CONCLUSION All three staging systems are independent prognostic factors for OS.LODDS demonstrated the highest specificity,making it especially useful for predicting outcomes,while pN was the most effective in homogeneous stratification,offering better patient differentiation.These findings highlight the complementary roles of LODDS and pN in enhancing prognostic accuracy and stratification.
基金Supported by NSFC (No.12361027)NSF of Inner Mongolia (No.2018MS01021)+1 种基金NSF of Shandong Province (No.ZR2020QA009)Science and Technology Innovation Program for Higher Education Institutions of Shanxi Province (No.2024L533)。
文摘In this paper,we give a complete characterization of all self-adjoint domains of odd order differential operators on two intervals.These two intervals with all four endpoints are singular(one endpoint of each interval is singular or all four endpoints are regulars are the special cases).And these extensions yield"new"self-adjoint operators,which involve interactions between the two intervals.
