Measuring the effectiveness of offensive match-play in professional soccer

Abstract

The broader measures of offensive effectiveness, such as scoring opportunities and shots at goal, are commonly used as an alternative to goals scored due to the naturally low probability of scoring (about 1%) in soccer match-play. These measures may enable soccer practitioners to objectively see behind single match results, which are often influenced by chance. The purpose of this study was to examine the relationship between broader measures (scoring opportunities and score box possessions) and the ultimate measure (goals scored) of offensive effectiveness. We analysed data from videotapes of 163 of 182 (90%) matches played in the Norwegian men's professional league during the 2004 season. Multiple logistic regression analyses showed very similar results when comparing the effectiveness of different offensive tactics, regardless of which outcome was used. For example, counterattacks were more effective than elaborate attacks in producing goals (odds ratio OR=2.07, 95% confidence interval: 1.40 to 3.05), scoring opportunities (OR=2.30, 95% confidence interval: 1.28 to 4.15), and score box possessions (OR=2.12, 95% confidence interval: 1.39 to 3.25). The receiver-operating characteristic function statistical procedure was used to examine the association between each of the three measures of offensive effectiveness: scoring opportunities, score box possessions, and goals scored. No significant difference was observed between the area under the curve (AUC) for the broader measures (scoring opportunities and score box possessions) and the ultimate measure (goals scored) of offensive effectiveness. The 95% confidence interval of the AUC for both scoring opportunities (0.74–0.84) and score box possessions (0.68–0.76) includes the AUC for goals scored (0.74). Thus, the results are very similar regardless of which outcome measure for offensive effectiveness is used. This indicates that scoring opportunities and score box possessions (shooting opportunities) can be used as a proxy for goals scored when comparing the effectiveness of different playing tactics in soccer. Compared with goals scored, using scoring opportunities or score box possessions requires smaller match samples for meaningful analyses, and may therefore be more feasible alternatives.     

论教师薪俸对民国大学教育与学术之影响

一所大学教师之良窳,关系该大学学风与学生品质,而大学教师的经济生活状况又是提升其教学与治学能力,从而提高其专业素质之重要保障。可以说,大学教师薪俸影响大学教育与学术的发展。民国大学教师的生活历经起伏跌宕,其经济生活状况大体经历了一个“不稳定——稳定——坠入困顿”的过程。因此,以民国大学教师薪俸状况为切入点,剖析薪俸对民国大学教师的专业素质水准,及其对民国大学教育与学术水平的影响。     

室内可见光局域网的研究

在室内无线光局域网中,可见光通信越来越引起了人们的关注。可见光通信具有发射功率高、无需申请频谱、无电磁干扰、节约能源等优点,因此注定会成为未来室内无线光通信的主角。提出了一种可见光局域网通信的模型,重点研究了基于无线光码分多址(WOCDMA)的信道共享方案。在以往的光正交码(OOC)基础上,采用了随机光码(random optical code)作为系统的扩频码,并对其相应的性能做了对比。     

用AUC评估分类器的预测性能

准确率一直被作为分类器预测性能的主要评估标准,但是它存在着诸多的缺点和不足。本文将准确率与AUC(the area under the Receiver Operating Characteristic curve)进行了理论上的对比分析,并分别使用AUC和准确率对3种分类学习算法在15个两类数据集上进行了评估。综合理论和实验两个方面的结果,显示了AUC不但优于而且应该替代准确率,成为更好的分类器性能的评估度量。同时,用AUC对3种分类学习算法的重新评估,进一步证实了基于贝叶斯定理的NaiveBayes和TAN-CMI分类算法优于决策树分类算法C4．5。     

Identifying students ‘at risk’ of withdrawal using ROC analysis of attendance data

Student retention has become increasingly important as student numbers continue to rise. Early identification of those students who are disengaging from their course is crucial if steps are to be taken to turn this around. Attendance data from the compulsory aspects of courses were gathered on a centrally held database during teaching week six of semester one. Students who did not meet a pre-set threshold of expected attendance, derived from ROC analysis of historical attendance data, were identified as ‘at risk’ of withdrawal to their Adviser of Studies during teaching week seven. These students were contacted and encouraged to make an appointment with their Adviser so that they could receive help with any difficulties they were having. The entire cohort was then reviewed in the following academic year to see if they had withdrawn, continued (in any year) or progressed to the second year of their programme.     

Activity optimization method in SPECT： A comparison with ROC analysisActivity optimization method in SPECT： A comparison with ROC analysis

A discriminant method for optimizing activity in nuclear medicine studies is validated by comparison with ROC （received operating characteristic）-curves. The method is tested in 21 single photon emission computerized tomography （SPECT）, performed with a cardiac phantom. Three different lesions （Lb L2 and L3） were placed in the myocardium-wall by pairs fbr each SPECT. Three activities （84, 37 or 18.5 MBq） of 99mTc were used as background. Linear discriminant analysis was used to select the parameters that characterize image quality among the measured variables in the images [（Background-to-Lesion （B/Li） and Signal-to-Noise （S/N） ratios）]. Two clusters with different image quality （P=0.021 ） were obtained. The ratios B/Lj, B/L2 and B/L3 are the parameters used to construct the function with 100% of cases correctly classified into the clusters. The value of 37 MBq was the lowest tested activity for which good results for the B/Li ratios were obtained. The result coincides with the applied ROC-analysis （r=0.89）.     

采用ROC曲线法建立大学生健康步行量参考标准研究

目的:分析大学生步行量与体质的关系,建立大学生步行量参考标准;方法:使用计步器调查302名大学生1周的步行量,并进行体质健康测试,采用Person相关法分析步行量与各项体质指标的相关性,采用ROC曲线法建立大学生健康步行量参考标准;结果:大学生步行量与BMI、台阶指数、肺活量体重指数及体质健康测试总分之间有低度相关性,采用ROC曲线法可建立台阶指数及格、肺活量体重指数及格和体质健康测试及格所对应的步行量切点;结论:11 000步/天可作为大学生步行量参考标准。     

Activity optimization method in SPECT:A comparison with ROC analysis

INTRODUCTION Image quality in nuclear medicine tomography is critically dependent on the activity undergone by the patient. The optimal activity is the smallest amount of activity which preserves diagnostic accuracy. Nev- ertheless, the optimum depends on the gamma camera used for imaging, the size of the patient and the im- aging application (Mattsson et al., 1998). To optimize, one has to study how diagnostic accuracy depends on the activity undergone for each particular study, taking i…     

心喘灵(xc-1)的钙拮抗作用

心喘灵(xc-1)抑制异丙肾上腺素加快大鼠右心房自发性频率的作用。能使量效反应曲线右移。xc-1也抑制大鼠主动脉螺旋条由高 k+去极化和 NA 诱发收缩张力增加作用。xc-1与沛心达作用相似,都有钙拮抗作用,能抑制 ROC 和 PDC。并证明 PDC 与 ROC 分别为膜上两种各自独立的通道,xc-1与沛心达对两者都有抑制作用。     

民国学前教育思想编著、期刊文论的计量与分析

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