Referee bias contributes to home advantage in English Premiership football

Abstract

Officiating bias is thought to contribute to home advantage. Recent research has shown that sports with subjective officiating tend to experience greater home advantage and that referees' decisions can be influenced by crowd noise, but little work has been done to examine whether individual referees vary in their home bias or whether biased decisions contribute to overall home advantage. We develop an ordinal regression model to determine whether various measures of home advantage are affected by the official for the match and by crowd size while controlling for team ability. We examine 5244 English Premier League (EPL) match results involving 50 referees and find that home bias differs between referees. Individual referees give significantly different levels of home advantage, measured as goal differential between the home and away teams, although the significance of this result depends on one referee with a particularly high home advantage (an outlier). Referees vary significantly and robustly in their yellow card and penalty differentials even excluding the outlier. These results confirm that referees are responsible for some of the observed home advantage in the EPL and suggest that home advantage is dependent on the subjective decisions of referees that vary between individuals. We hypothesize that individual referees respond differently to factors such as crowd noise and suggest further research looking at referees' psychological and behavioural responses to biased crowds.     

Injuries in handball: Examination of the risk factors

Abstract

This paper examines the influence of selected risk factors on injuries among male players of competition handball. Data relating to risk factors were collected using a self-report questionnaire. The factors that were examined were age, height, weight, body mass index, field position, past sport experience, level of competition, pre-season conditioning, number of practices per week, frequency of participation in games, use of prophylactic equipment, use of stretching exercises, and technical training. The questionnaire was administered to 216 male handball players. Nearly half of the players (42.6% or n=92) reported that they had been injured during the previous two years. The injury incidence was 8.14 injuries per 1,000 game hours for the preceding two years. Logistic regression analysis revealed that the variables “use of prophylactic equipment” and the “number of practices per week” contributed significantly to the prediction of an injury in handball players. The results of this study suggest that it is possible to reduce injury occurrence by giving specific attention to players using prophylactic equipment and to the lower-competition-level players.     

大学生肺活量与身体素质相关性研究

本研究通过对2239名大学生进行肺活量、50米、立定跳远、握力、坐位体前屈、男1000米、女800米和仰卧起坐项目测试,采用数理统计、相关性、多元逐步回归分析等研究方法,建立大学生肺活量回归方程：男生肺活量（mL）=2949.95（mL）+26.67×握力（Kg）+5.52×坐位体前屈（cm）;女生肺活量（mL）=1913.40（mL）+18.03×握力（Kg）+2.34×立定跳远（cm）+3.29仰卧起坐（个）。     

Informing in-season tactical periodisation in team sport: development of a match difficulty index for Super Rugby

In team sports, tactical periodisation refers to the planned manipulation of training loads with the aim of prioritising athlete readiness for matches of greatest importance. Although monitoring of athletes’ physical condition is often used to inform this planning, the direct influence of external factors on match difficulty has not been well quantified. In this study, a ‘match difficulty index’ (MDI) for use in Super Rugby was developed, based on the influence imparted by five external factors on previous match outcomes. Specifically, information relating to match location, days break between matches, time-zone change and opposition ladder position (both current and previous year) were collected for matches played during the 2011–2013 Super Rugby seasons. Logistic regression analyses were used to assess the importance of each of these factors with respect to match outcome (win/loss), with opposition ladder position and match location (home, domestic away or international) exerting the greatest influence on match difficulty. Three separate cross-validated models were constructed, with match outcome classification performance reported as 66.2%, 65.5% and 63.7% respectively. The three MDI models emanating from this study can each be used to inform tactical periodisation program design both prior to and during the regular season.     

Explaining match outcome in elite Australian Rules football using team performance indicators

The relationships between team performance indicators and match outcome have been examined in many team sports, however are limited in Australian Rules football. Using data from the 2013 and 2014 Australian Football League (AFL) regular seasons, this study assessed the ability of commonly reported discrete team performance indicators presented in their relative form (standardised against their opposition for a given match) to explain match outcome (Win/Loss). Logistic regression and decision tree (chi-squared automatic interaction detection (CHAID)) analyses both revealed relative differences between opposing teams for “kicks” and “goal conversion” as the most influential in explaining match outcome, with two models achieving 88.3% and 89.8% classification accuracies, respectively. Models incorporating a smaller performance indicator set displayed a slightly reduced ability to explain match outcome (81.0% and 81.5% for logistic regression and CHAID, respectively). However, both were fit to 2014 data with reduced error in comparison to the full models. Despite performance similarities across the two analysis approaches, the CHAID model revealed multiple winning performance indicator profiles, thereby increasing its comparative feasibility for use in the field. Coaches and analysts may find these results useful in informing strategy and game plan development in Australian Rules football, with the development of team-specific models recommended in future.     

体育多种评价方法的比较研究

运用相关系数的归一化、标准百分的类比和多类多级判别分析的理论方法，分析于娟推铅球的专项素质对专项成绩影响的重要性大小排序，其排序的评价结果较一致。对这3种方法作为评价手段进行相互比较，相关系数的归一化评价方法较其它2种评价方法合理。     

CBA2011-2012赛季常规赛得分与各项技术指标关系的回归分析

采用逐步回归分析法对CBA2011-2012赛季常规赛17支球队各项技术统计数据与得分的关系进行研究,研究结果表明:在影响CBA 2011-2012赛季常规赛各队得分能力的众多指标中,2分命中率和失误次数是影响比赛得分多少的主要因素.本研究旨在为CBA各球队提高得分能力和比赛成绩提供理论依据.     

CBA联赛近5年冠军球队主要技术指标与比赛得分情况的统计分析

运用文献资料、数理统计、灰色关联分析等方法对2005至2010年5届CBA联赛各届冠军球队241场比赛技术统计指标与比赛得分进行量化研究,并建立指标的灰关联序列与回归模型。研究表明:影响冠军球队得分的各指标因素的主次关系依次是罚球命中率、犯规、防守篮板、助攻、失误、进攻篮板、抢断、盖帽、三分命中率、投篮命中率;影响比赛得分较为显著的指标为罚球命中率、投篮命中率、三分命中率、进攻篮板、防守篮板、抢断、失误、犯规。     

基于γ-散度的稳健有序误标记logistic回归

有序多分类方法已经得到了广泛研究。传统的有序多分类方法假设样本的类别标签是不存在误标记的。但是由于实际数据复杂以及人工经验有限,获得标记完全正确的样本是不现实的,因此,传统的方法就存在局限性。提出一种基于γ-散度的有序误标记logistic回归方法,在处理存在误标记的有序多分类问题时具有很强的稳健性,也就是说,当某一样本被错误标记时它对参数估计的权重小于其被正确标记时的权重。该方法通过最小化γ-散度构建模型,利用梯度下降算法求解模型,不仅具有很强的稳健性而且在模型中可以忽略误标记概率。模拟研究和真实数据分析都说明该有序误标记logistic回归方法在处理存在误标记的有序分类问题时效果很好。     

北京市男子大学生足球运动员运动损伤特征与风险因素筛查

摘要：目的：掌握北京市男子大学生足球运动员运动损伤的流行情况,对导致运动损伤发生的风险因素进行筛查,为进一步预防男子大学生足球运动损伤的发生提供依据。方法：应用方便分层抽样的方法,对参加北京市男子大学生足球联赛甲、乙、丙组的14所高校249名在校大学生足球运动员的损伤情况进行调查,应用T检验、单因素χ2检验与二元非条件logistic回归模型进行分析。结果与结论：充分了解了北京市男子大学生足球运动员的运动损伤现状和特征;筛查出为运动损伤发生的主要的风险因素;错误的技术动作、对手的粗野动作导致损伤发生的主要诱发事件。