Test case prioritization techniques have been focused on regression testing which is conducted on an already executed test suite. In fact, the test case prioritization for new testing is also required. In this paper, ...Test case prioritization techniques have been focused on regression testing which is conducted on an already executed test suite. In fact, the test case prioritization for new testing is also required. In this paper, we propose a method to prioritize new test cases by calculating risk exposure value for requirements and analyzing risk items based on the calculation to evaluate relevant test cases and thereby determining the test case priority through the evaluated values. Moreover, we demonstrate effectiveness of our technique through empirical studies in terms of both APFD and fault severity.展开更多
The Research on Market Risks has been developed abroad in all sorts of markets since 1960＇s. It＇s necessary to comprehend and consider opportunity and challenge in Chinese futures market from the viewpoint of risk m...The Research on Market Risks has been developed abroad in all sorts of markets since 1960＇s. It＇s necessary to comprehend and consider opportunity and challenge in Chinese futures market from the viewpoint of risk management. With different ARCH models, we find heteroscedasticity does exist in Chinese market, so we adopt the Variance Ratio. We test empirically the prices of Chinese futures market from 1993 to 2002. The results show that only futures price of copper meets the random walk, thereby confirming the weak form market efficiency. It also means that the function of price discovery is weak and the risk of futures market is poor. Finally, we give much constructive policy advice.展开更多
It is well-known that the power of Cochran’s Q test to assess the presence of heterogeneity among treatment effects in a clinical meta-analysis is low due to the small number of studies combined. Two modified tests (...It is well-known that the power of Cochran’s Q test to assess the presence of heterogeneity among treatment effects in a clinical meta-analysis is low due to the small number of studies combined. Two modified tests (PL1, PL2) were proposed by replacing the profile maximum likelihood estimator (PMLE) into the variance formula of logarithm of risk ratio in the standard chi-square test statistic for testing the null common risk ratios across all k studies (i = 1, L, k). The simply naive test (SIM) as another comparative candidate has considerably arisen. The performance of tests in terms of type I error rate under the null hypothesis and power of test under the random effects hypothesis was done via a simulation plan with various combinations of significance levels, numbers of studies, sample sizes in treatment and control arms, and true risk ratios as effect sizes of interest. The results indicated that for moderate to large study sizes (k?≥ 16)?in combination with moderate to large sample sizes?(?≥ 50), three tests (PL1, PL2, and Q) could control type I error rates in almost all situations. Two proposed tests (PL1, PL2) performed best with the highest power when?k?≥ 16?and moderate sample sizes (= 50,100);this finding was very useful to make a recommendation to use them in practical situations. Meanwhile, the standard Q test performed best when?k?≥ 16 and large sample sizes (≥ 500). Moreover, no tests were reasonable for small sample sizes (≤ 10), regardless of study size k. The simply naive test (SIM) is recommended to be adopted with high performance when k = 4 in combination with (≥ 500).展开更多
Cardiovascular disease(CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus,who have a risk of cardiovascular mortality two to four times that of people without diabetes.An indivi...Cardiovascular disease(CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus,who have a risk of cardiovascular mortality two to four times that of people without diabetes.An individualised approach to cardiovascular risk estimation and management is needed.Over the past decades,many risk scores have been developed to predict CVD.However,few have been externally validated in a diabetic population and limited studies have examined the impact of applying a prediction model in clinical practice.Currently,guidelines are focused on testing for CVD in symptomatic patients.Atypical symptoms or silent ischemia are more common in the diabetic population,and with additional markers of vascular disease such as erectile dysfunction and autonomic neuropathy,these guidelines can be difficult to interpret.We propose an algorithm incorporating cardiovascular risk scores in combination with typical and atypical signs and symptoms to alert clinicians to consider further investigation with provocative testing.The modalities for investigation of CVD are discussed.展开更多
Consider I pairs of independent binomial variates x0i and x1i with corresponding parameters P0i and p1i and sample sizes n0i and n1i for i=1, …,I. Let △i = P1i-P0i be the difference of the two binomial parameters, w...Consider I pairs of independent binomial variates x0i and x1i with corresponding parameters P0i and p1i and sample sizes n0i and n1i for i=1, …,I. Let △i = P1i-P0i be the difference of the two binomial parameters, where △i’s are to be of interest and P0i’s are nuisance parameters. The null hypothesis of homogeneity on the risk difference can be written as展开更多
AIM:To determine the role of the fecal immunochemical test(FIT),used to evaluate fecal hemoglobin concentration,in the prediction of histological grade and risk of colorectal tumors.METHODS:We enrolled 17881 individua...AIM:To determine the role of the fecal immunochemical test(FIT),used to evaluate fecal hemoglobin concentration,in the prediction of histological grade and risk of colorectal tumors.METHODS:We enrolled 17881 individuals who attended the two-step colorectal cancer screening program in a single hospital between January 2010 and October 2011.Colonoscopy was recommended to the participants with an FIT of≥12 ngHb/mL buffer.We classified colorectal lesions as cancer(C),advanced adenoma(AA),adenoma(A),and others(O)by their colonoscopic and histological findings.Multiple linear regression analysis adjusted for age and gender was used to determine the association between the FIT results and colorectal tumor grade.The risk of adenomatous neoplasia was estimated by calculating the positive predictive values for different FIT concentrations.RESULTS:The positive rate of the FIT was 10.9%(1948/17881).The attendance rate for colonoscopy was 63.1%(1229/1948).The number of false positive results was 23.Of these 1229 cases,the numbers of O,A,AA,and C were 759,221,201,and 48,respectively.Regression analysis revealed a positive association between histological grade and FIT concentration(β=0.088,P<0.01).A significant log-linear relationship was found between the concentration and positive predictive value of the FIT for predicting colorectal tumors(R2>0.95,P<0.001).CONCLUSION:Higher FIT concentrations are associated with more advanced histological grades.Risk prediction for colorectal neoplasia based on individual FIT concentrations is significant and may help to improve the performance of screening programs.展开更多
Due to the high difficulties, high investment, and high risks in deepwater oil and gas well testing, major safety problems can occur easily. A key to prevent accidents is to conduct safety assessment and control on de...Due to the high difficulties, high investment, and high risks in deepwater oil and gas well testing, major safety problems can occur easily. A key to prevent accidents is to conduct safety assessment and control on deepwater testing and to improve the testing technology. The deepwater of the South China Sea has some special environmental features: long distance from offshore, frequent typhoons in summer and constant monsoons in winter, and the presence of sandy slopes, sandy ridges and internal waves, coupled with the complex properties of oil and gas reserves which bring more challenges to deepwater well testing. In combination with deepwater well testing practice in the South China Sea, this paper analyzes the main potential risks in deepwater well testing and concludes that there are risks of failures of testing string, tools, and ground processes. Other risks are gas hydrate blockage, reservoir stratum sanding, and typhoon impacts. Specific precautions are also proposed in response to these risks in the paper.展开更多
AIM: To investigate the added value of myocardial perfusion scintigraphy imaging (MPI) in consecutive patients with suspected coronary artery disease (CAD) and a recent, normal exercise electrocardiography (ECG). METH...AIM: To investigate the added value of myocardial perfusion scintigraphy imaging (MPI) in consecutive patients with suspected coronary artery disease (CAD) and a recent, normal exercise electrocardiography (ECG). METHODS: This study was a retrospective analysis of consecutive patients referred for MPI during a 2-year period from 2006-2007 at one clinic. All eligible patients were suspected of suffering from CAD, and had performed a satisfactory bicycle exercise test (i.e. , peak heart rate > 85% of the expected, age-predicted maximum) within 6 mo of referral, their exercise ECG was had no signs of ischemia, there was no exercise-limiting angina, and no cardiac events occurred between the exercise test and referral. The patients subsequently underwent a standard 2-d, stress-rest exercise MPI. Ischemia was defined based on visual scoring supported by quantitative segmental analysis (i.e. , sum of stress score > 3). The results of cardiac catheterizationwere analyzed, and clinical follow up was performed by review of electronic medical files. RESULTS: A total of 56 patients fulfilled the eligibility criteria. Most patients had a low or intermediate ATPⅢ pretest risk of CAD (6 patients had a high pre-test risk). The referral exercise test showed a mean Duke score of 5 (range: 2 to 11), which translated to a low postexercise risk in 66% and intermediate risk in 34%. A total of seven patients were reported with ischemia by MPI. Three of these patients had high ATPⅢ pre-test risk scores. Six of these seven patients underwent cardiac catheterization, which showed significant stenosis in one patient with a high pre-test risk of CAD, and indeterminate lesions in three patients (two of whom had high pre-test risk scores). With MPI as a gate keeper for catheterization, no significant, epicardial stenosis was observed in any of the 50 patients (0%, 95% confidence interval 0.0 to 7.1) with low to intermediate pre-test risk of CAD and a negative exercise test. No cardiac events occurred in any patients within a median follow up period of > 1200 d. CONCLUSION: The added diagnostic value of MPI in patients with low or intermediate risk of CAD and a recent, normal exercise test is marginal.展开更多
This paper is concerned with the statistical modeling of the dependence structure of multivariate financial data using the copula, and the application of copula functions in VaR valuation. After the introduction of th...This paper is concerned with the statistical modeling of the dependence structure of multivariate financial data using the copula, and the application of copula functions in VaR valuation. After the introduction of the pure copula method and the maximum and minimum mixture copula method, authors present a new algorithm based on the more generalized mixture copula functions and the dependence measure, and apply the method to the portfolio of Shanghai stock composite index and Shenzhen stock component index. Comparing with the results from various methods, one can find that the mixture copula method is better than the pure Gaussian copula method and the maximum and minimum mixture copula method on different VaR level.展开更多
Encroachment, disposal of untreated domestic and industrial wastewater and dumping of solid wastes have degraded the overall quality of the river Turag, which is located in Dhaka—the Capital City of Bangladesh. The p...Encroachment, disposal of untreated domestic and industrial wastewater and dumping of solid wastes have degraded the overall quality of the river Turag, which is located in Dhaka—the Capital City of Bangladesh. The present study investigated the extent of pollution of sediments of this river and analyzed the regional variability for the concentrations of Cr, Pb, Zn, Cu and Cd—all of concern because of their potential toxicity, using atomic absorption spectrophotometer. As per US EPA sediment quality guideline, metal concentrations ranged between Cd: 0.00 - 0.80, Cr: 32.00 - 75.50, Cu: 46.30 - 60.00, Pb: 28.30 - 36.40, and Zn: 94.60 - 190.10 mg/kg in the Turag river sediments. Cr, Cu, Zn belongs to moderately to highly polluted, Pb and Cd belongs to not polluted for Turag river. The heavy metals contamination in the sediments were also evaluated by applying Index of geo-accumulation (Igeo), contamination factor (Cf), pollution load index (PLI) etc. Toxicity characteristics leaching procedure (TCLP) test (US EPA 1311) for sediment samples have been performed also for metals (Pb, Cd, Cr, Cu and Zn) to determine the readily toxicity level of heavy metals. Sieve analysis of sediment performed in this study to determine the physical characteristic of sediment samples. The metal concentrations are well below the regulated level as per US EPA. This index can be complemented with the contamination index, which allows more site-specific and accurate information on contaminant levels. If the aim of work on contamination evaluation is to assess the overall contamination of a study area, the indices are highly appropriate.展开更多
A complex mechatronics system Bayesian plan of demonstration test is studied based on the mixed beta distribution. During product design and improvement various information is appropriately considered by introducing i...A complex mechatronics system Bayesian plan of demonstration test is studied based on the mixed beta distribution. During product design and improvement various information is appropriately considered by introducing inheritance factor, moreover, the inheritance factor is thought as a random variable, and the Bayesian decision of the qualification test plan is obtained, and the correctness of a Bayesian model presented is verified. The results show that the quantity of the test is too conservative according to classical methods under small binomial samples. Although traditional Bayesian analysis can consider test information of related or similar products, it ignores differences between such products. The method has solved the above problem, furthermore, considering the requirement in many practical projects, the differences among this method, the classical method and Bayesian with beta distribution are compared according to the plan of reliability acceptance test.展开更多
文摘Test case prioritization techniques have been focused on regression testing which is conducted on an already executed test suite. In fact, the test case prioritization for new testing is also required. In this paper, we propose a method to prioritize new test cases by calculating risk exposure value for requirements and analyzing risk items based on the calculation to evaluate relevant test cases and thereby determining the test case priority through the evaluated values. Moreover, we demonstrate effectiveness of our technique through empirical studies in terms of both APFD and fault severity.
文摘The Research on Market Risks has been developed abroad in all sorts of markets since 1960＇s. It＇s necessary to comprehend and consider opportunity and challenge in Chinese futures market from the viewpoint of risk management. With different ARCH models, we find heteroscedasticity does exist in Chinese market, so we adopt the Variance Ratio. We test empirically the prices of Chinese futures market from 1993 to 2002. The results show that only futures price of copper meets the random walk, thereby confirming the weak form market efficiency. It also means that the function of price discovery is weak and the risk of futures market is poor. Finally, we give much constructive policy advice.
文摘It is well-known that the power of Cochran’s Q test to assess the presence of heterogeneity among treatment effects in a clinical meta-analysis is low due to the small number of studies combined. Two modified tests (PL1, PL2) were proposed by replacing the profile maximum likelihood estimator (PMLE) into the variance formula of logarithm of risk ratio in the standard chi-square test statistic for testing the null common risk ratios across all k studies (i = 1, L, k). The simply naive test (SIM) as another comparative candidate has considerably arisen. The performance of tests in terms of type I error rate under the null hypothesis and power of test under the random effects hypothesis was done via a simulation plan with various combinations of significance levels, numbers of studies, sample sizes in treatment and control arms, and true risk ratios as effect sizes of interest. The results indicated that for moderate to large study sizes (k?≥ 16)?in combination with moderate to large sample sizes?(?≥ 50), three tests (PL1, PL2, and Q) could control type I error rates in almost all situations. Two proposed tests (PL1, PL2) performed best with the highest power when?k?≥ 16?and moderate sample sizes (= 50,100);this finding was very useful to make a recommendation to use them in practical situations. Meanwhile, the standard Q test performed best when?k?≥ 16 and large sample sizes (≥ 500). Moreover, no tests were reasonable for small sample sizes (≤ 10), regardless of study size k. The simply naive test (SIM) is recommended to be adopted with high performance when k = 4 in combination with (≥ 500).
文摘Cardiovascular disease(CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus,who have a risk of cardiovascular mortality two to four times that of people without diabetes.An individualised approach to cardiovascular risk estimation and management is needed.Over the past decades,many risk scores have been developed to predict CVD.However,few have been externally validated in a diabetic population and limited studies have examined the impact of applying a prediction model in clinical practice.Currently,guidelines are focused on testing for CVD in symptomatic patients.Atypical symptoms or silent ischemia are more common in the diabetic population,and with additional markers of vascular disease such as erectile dysfunction and autonomic neuropathy,these guidelines can be difficult to interpret.We propose an algorithm incorporating cardiovascular risk scores in combination with typical and atypical signs and symptoms to alert clinicians to consider further investigation with provocative testing.The modalities for investigation of CVD are discussed.
文摘Consider I pairs of independent binomial variates x0i and x1i with corresponding parameters P0i and p1i and sample sizes n0i and n1i for i=1, …,I. Let △i = P1i-P0i be the difference of the two binomial parameters, where △i’s are to be of interest and P0i’s are nuisance parameters. The null hypothesis of homogeneity on the risk difference can be written as
文摘AIM:To determine the role of the fecal immunochemical test(FIT),used to evaluate fecal hemoglobin concentration,in the prediction of histological grade and risk of colorectal tumors.METHODS:We enrolled 17881 individuals who attended the two-step colorectal cancer screening program in a single hospital between January 2010 and October 2011.Colonoscopy was recommended to the participants with an FIT of≥12 ngHb/mL buffer.We classified colorectal lesions as cancer(C),advanced adenoma(AA),adenoma(A),and others(O)by their colonoscopic and histological findings.Multiple linear regression analysis adjusted for age and gender was used to determine the association between the FIT results and colorectal tumor grade.The risk of adenomatous neoplasia was estimated by calculating the positive predictive values for different FIT concentrations.RESULTS:The positive rate of the FIT was 10.9%(1948/17881).The attendance rate for colonoscopy was 63.1%(1229/1948).The number of false positive results was 23.Of these 1229 cases,the numbers of O,A,AA,and C were 759,221,201,and 48,respectively.Regression analysis revealed a positive association between histological grade and FIT concentration(β=0.088,P<0.01).A significant log-linear relationship was found between the concentration and positive predictive value of the FIT for predicting colorectal tumors(R2>0.95,P<0.001).CONCLUSION:Higher FIT concentrations are associated with more advanced histological grades.Risk prediction for colorectal neoplasia based on individual FIT concentrations is significant and may help to improve the performance of screening programs.
文摘Due to the high difficulties, high investment, and high risks in deepwater oil and gas well testing, major safety problems can occur easily. A key to prevent accidents is to conduct safety assessment and control on deepwater testing and to improve the testing technology. The deepwater of the South China Sea has some special environmental features: long distance from offshore, frequent typhoons in summer and constant monsoons in winter, and the presence of sandy slopes, sandy ridges and internal waves, coupled with the complex properties of oil and gas reserves which bring more challenges to deepwater well testing. In combination with deepwater well testing practice in the South China Sea, this paper analyzes the main potential risks in deepwater well testing and concludes that there are risks of failures of testing string, tools, and ground processes. Other risks are gas hydrate blockage, reservoir stratum sanding, and typhoon impacts. Specific precautions are also proposed in response to these risks in the paper.
文摘AIM: To investigate the added value of myocardial perfusion scintigraphy imaging (MPI) in consecutive patients with suspected coronary artery disease (CAD) and a recent, normal exercise electrocardiography (ECG). METHODS: This study was a retrospective analysis of consecutive patients referred for MPI during a 2-year period from 2006-2007 at one clinic. All eligible patients were suspected of suffering from CAD, and had performed a satisfactory bicycle exercise test (i.e. , peak heart rate > 85% of the expected, age-predicted maximum) within 6 mo of referral, their exercise ECG was had no signs of ischemia, there was no exercise-limiting angina, and no cardiac events occurred between the exercise test and referral. The patients subsequently underwent a standard 2-d, stress-rest exercise MPI. Ischemia was defined based on visual scoring supported by quantitative segmental analysis (i.e. , sum of stress score > 3). The results of cardiac catheterizationwere analyzed, and clinical follow up was performed by review of electronic medical files. RESULTS: A total of 56 patients fulfilled the eligibility criteria. Most patients had a low or intermediate ATPⅢ pretest risk of CAD (6 patients had a high pre-test risk). The referral exercise test showed a mean Duke score of 5 (range: 2 to 11), which translated to a low postexercise risk in 66% and intermediate risk in 34%. A total of seven patients were reported with ischemia by MPI. Three of these patients had high ATPⅢ pre-test risk scores. Six of these seven patients underwent cardiac catheterization, which showed significant stenosis in one patient with a high pre-test risk of CAD, and indeterminate lesions in three patients (two of whom had high pre-test risk scores). With MPI as a gate keeper for catheterization, no significant, epicardial stenosis was observed in any of the 50 patients (0%, 95% confidence interval 0.0 to 7.1) with low to intermediate pre-test risk of CAD and a negative exercise test. No cardiac events occurred in any patients within a median follow up period of > 1200 d. CONCLUSION: The added diagnostic value of MPI in patients with low or intermediate risk of CAD and a recent, normal exercise test is marginal.
基金Supported by Research Projects of Humanities and Social Sciences Foundation of Ministry of Education
文摘This paper is concerned with the statistical modeling of the dependence structure of multivariate financial data using the copula, and the application of copula functions in VaR valuation. After the introduction of the pure copula method and the maximum and minimum mixture copula method, authors present a new algorithm based on the more generalized mixture copula functions and the dependence measure, and apply the method to the portfolio of Shanghai stock composite index and Shenzhen stock component index. Comparing with the results from various methods, one can find that the mixture copula method is better than the pure Gaussian copula method and the maximum and minimum mixture copula method on different VaR level.
文摘Encroachment, disposal of untreated domestic and industrial wastewater and dumping of solid wastes have degraded the overall quality of the river Turag, which is located in Dhaka—the Capital City of Bangladesh. The present study investigated the extent of pollution of sediments of this river and analyzed the regional variability for the concentrations of Cr, Pb, Zn, Cu and Cd—all of concern because of their potential toxicity, using atomic absorption spectrophotometer. As per US EPA sediment quality guideline, metal concentrations ranged between Cd: 0.00 - 0.80, Cr: 32.00 - 75.50, Cu: 46.30 - 60.00, Pb: 28.30 - 36.40, and Zn: 94.60 - 190.10 mg/kg in the Turag river sediments. Cr, Cu, Zn belongs to moderately to highly polluted, Pb and Cd belongs to not polluted for Turag river. The heavy metals contamination in the sediments were also evaluated by applying Index of geo-accumulation (Igeo), contamination factor (Cf), pollution load index (PLI) etc. Toxicity characteristics leaching procedure (TCLP) test (US EPA 1311) for sediment samples have been performed also for metals (Pb, Cd, Cr, Cu and Zn) to determine the readily toxicity level of heavy metals. Sieve analysis of sediment performed in this study to determine the physical characteristic of sediment samples. The metal concentrations are well below the regulated level as per US EPA. This index can be complemented with the contamination index, which allows more site-specific and accurate information on contaminant levels. If the aim of work on contamination evaluation is to assess the overall contamination of a study area, the indices are highly appropriate.
基金National Advanced Research Project of China(No.51319030302)National Advanced Research Foundation of China(No.9140A 19030506KG0166)
文摘A complex mechatronics system Bayesian plan of demonstration test is studied based on the mixed beta distribution. During product design and improvement various information is appropriately considered by introducing inheritance factor, moreover, the inheritance factor is thought as a random variable, and the Bayesian decision of the qualification test plan is obtained, and the correctness of a Bayesian model presented is verified. The results show that the quantity of the test is too conservative according to classical methods under small binomial samples. Although traditional Bayesian analysis can consider test information of related or similar products, it ignores differences between such products. The method has solved the above problem, furthermore, considering the requirement in many practical projects, the differences among this method, the classical method and Bayesian with beta distribution are compared according to the plan of reliability acceptance test.
