Strength Of Opponents Research Articles

Analysing the impact of field conditions, pitch features, and opponent strength on cricket performance: A machine learning approach

Analysing the impact of field conditions, pitch features, and opponent strength on cricket performance: A machine learning approach

Are there meaningful changes in the performance of professional soccer teams from the first half of the match to the second? Evidence from the data of eight consecutive seasons of the Chinese Super League

ABSTRACT In the aim to better understanding the dynamic of performance changes between the first and second halves of professional soccer teams, statistics of 1899 matches from 2012 to 2019 of the Chinese Super League (CSL) were collected and analysed. The generalised mixed linear modelling was used to estimate the mean change of each of 40 physical and technical performance-related parameters of soccer teams from the first half of the match to the second, controlling the effects of match status, match location, team strength and opponent strength. Results showed that, out of the selected 40 parameters, only goals (first half vs second half M ± SD: 0.60 ± 0.76 vs 0.82 ± 0.92, ES; ±99% confidence limits: 0.21; ±0.05), shots (5.7 ± 2.8 vs 6.8 ± 3.3, 0.34; ±0.05), individual possession in the attacking third (55 ± 21 vs 62 ± 25, 0.31; ±0.05), cross (9.7 ± 4.6 vs 10.9 ± 5.8, 0.24; ±0.06) and yellow cards (0.75 ± 0.84 vs 1.24 ± 1.07, 0.45; ±0.06) showed substantially increment from the first half to the second, other parameters presented only trivial changes. Hence, it is concluded that the physical performance of soccer teams in the second half did not show meaningful change, while technical actions related to attacking tended to increase. The findings can offer soccer coaches valuable insights into when and how to adjust their tactics, manage their players, thus can maintain or enhance the team’s match performance.

Home Advantage and Away Disadvantage of Teams in Champions League: Is It Valid for All Teams and Against Every Opponent?

The home advantage (HA) is a robust phenomenon in soccer whereby the home team wins more games and scores more goals than the away team. Similarly, away disadvantage (AD) means that an away team loses more games or scores less goals than the home team. This study examines the HA and AD values of teams in the UEFA-Champions League, covering the seasons from 2003/2004 to 2021/2022, a total of 2,344 matches. Controlling for team ability differences, the study revealed significant variations in HA, ranging from 32.1% to 79.5%, while AD values ranged from 45.1% to 71.9%. The study further found that HA remained consistent for teams across both the group and knockout stages, while AD varied between these stages. Furthermore, the results suggest that, for certain teams, HA is predominantly manifested against weaker opponents, and the impact of opponent strength on HA and AD is limited.

The Influence of Competition Rules on the Difficulty Groups of Aerobics

The competition rules are the directional indicators of competitive sports, which not only restrict the direction of sports technology, but also promote the development of sports events. Difficulty movements are an important component of aerobics, determining the level of athletes' competition results, and also one of the important judgments of judges. The selection and use of difficulty action groups for participating athletes should comply with the requirements of the rules. There are a total of four difficulty groups in aerobics. In competition statistics, Group C has the highest usage rate of nearly 50% among the four groups, while Group B has the least number of difficulty choices and a relatively single difficulty type. Considering the adjustment of one's own set of difficulty groups based on the opponent's strength, the athlete's performance system during the competition exhibits a three-dimensional, open, fluctuating, and multivariate complex control system.

MATHEMATICAL MODEL OF ASSESSMENT OF QUALITATIVE CHANGES IN EXECUTION OF TEAM ACTIONS BASED ON THE WILCOXON T-TEST

Volleyball has become one of the fastest, strongest and most exciting sports in our time. The game focuses on speed, power of attacks and productive long rallies, where competent defensive technique is important. The use of statistics in this sport plays a key role in objective analysis of various parameters of the game. Coaches use this data to identify players’ strengths and weaknesses and develop new training methods to improve various aspects of volleyball. The purpose of the study was to mathematically determine the result of performing certain actions during a certain period of time and to conclude the effectiveness of these actions reflected in the statistical data. In the interval between the two measurements, a special training volume was performed on the ”Serve” game action. According to the obtained results and their processing, with the use of the Wilcoxon T-test for connected samples, hypotheses were proposed and confirmed regarding two characteristics of the game action ”serve”: the number of serves aces and the number of errors. As a result, the hypothesis regarding the significant improvement in the number of servings aces as a result of the experiment and the null hypothesis regarding serving errors, that no significant changes occurred, were confirmed. Conclusions. Thanks to this study, we obtained a mechanism for evaluating changes within the studied mathematical model of the game. This evaluation criterion can be used to evaluate changes in other game qualities that will be used in the mathematical model. The issue of equal distribution depending on the strength of opponents and the selection of appropriate coefficients for conducting such studies remains problematic.

Coronavirus and sports leagues: obtaining a fair ranking when the season cannot resume

Many sports leagues are played in a tightly scheduled round-robin format, leaving a limited time window to postpone matches. If the season cannot resume due to an external shock such as the coronavirus pandemic in 2020, the ranking of the teams becomes non-trivial: it is necessary to account for schedule imbalances and possibly for the different number of matches played. First in the literature, we identify a set of desired axioms for ranking in these incomplete tournaments. It is verified that the generalized row sum, a parametric family of scoring rules, satisfies all of them. In particular, the well-established least-squares method maximizes the influence of the strength of opponents on the ranking. Our approach is applied for six major premier European soccer competitions, where the rankings are found to be robust concerning the weight of adjustment for the strength of the opponents. Some methodologically simpler alternative policies are also discussed.

HUBUNGAN TINGKAT KEKUATAN OTOT DENGAN PRESTASI ATLET CABANG OLAHRAGA JUDO PADA PEKAN OLAHRAGA NASIONAL (PON) XVIII 2012 DI RIAU

Judo is described as a physical contact sport. A judo athlete should try to make themovement of throwing, slamming and holding the opponent's strength during the game. To perform the technique well, muscle strength is important in judo athletes. As one of the components of physical fitness in athletes, muscle strength has an important role for the judo athlete to maximize their performance and have their best achievement. Therefore, this study aims to determine the relationship of muscle strength level of judo athletes with their achievement in Pekan Olahraga Nasional (PON) XVIII 2012 in Riau. A cross-sectional study using the analytical method was done on 19 Judo athletes as subjects. Data are collected from secondary data as a result of muscle strength examination measured by push, pull, and leg dynamometer, conducted by Komite Olah Raga Nasional (KONI) West Java. Judo athletes who participated Pekan Olah Raga Nasional (PON) XVIII 2012 championship in Riau were included while athletes who injured were excluded. In this study judo athletes who won medals (got achievement) were 7 athletes, while those who did not win medals (did not get the achievement) were 12 athletes. The significance value (p-value) for the relationship of muscle strength with judo athlete’s achievement as measured by push dynamometer was 0.764, pull dynamometer was 0.570, and leg dynamometer was 0.132. In conclusion, there isno significant relationship between the level of muscle strength with the judo athlete’s achievement on Pekan Olah Raga Nasional (PON) XVIII 2012.

Bigger data, better questions, and a return to fourth down behavior: an introduction to a special issue on tracking datain the National football League

AbstractMost historical National Football League (NFL) analysis, both mainstream and academic, has relied on public, play-level data to generate team and player comparisons. Given the number of oft omitted variables that impact on-field results, such as play call, game situation, and opponent strength, findings tend to be more anecdotal than actionable. With the release of player tracking data, however, analysts can better ask and answer questions to isolate skill and strategy. In this article, we highlight the limitations of traditional analyses, and use a decades-old punching bag for analysts, fourth-down strategy, as a microcosm for why tracking data is needed. Specifically, we assert that, in absence of using the precise yardage needed for a first down, past findings supporting an aggressive fourth down strategy may have been overstated. Next, we synthesize recent work that comprises this special Journal of Quantitative Analysis in Sports issue into player tracking data in football. Finally, we conclude with some best practices and limitations regarding usage of this data. The release of player tracking data marks a transition for the league and its’ analysts, and we hope this issue helps guide innovation in football analytics for years to come.

Contextual Factors Influencing External and Internal Training Loads in Collegiate Men's Soccer.

Curtis, RM, Huggins, RA, Benjamin, CL, Sekiguchi, Y, Adams, WM, Arent, SM, Jain, R, Miller, SJ, Walker, AJ, and Casa, DJ. Contextual factors influencing external and internal training loads in collegiate men's soccer. J Strength Cond Res 34(2): 374-381, 2020-This study investigated factors influencing training loads (TL) in collegiate men's soccer. Total distance, high-speed running distance (>14.4 km·h), high-intensity heart-rate zone duration (HI HRZ, >70% heart rate relative to maximum), and session rating of perceived exertion were assessed daily from 107 male soccer players competing for 5 National Collegiate Athletics Association Division I teams. Differences between athlete role (starter and reserve), position (defender, midfielder, and forward), season phase (preseason, in-season, and postseason), days relative to match (MD-1 to MD-5+), days between matches (<4, 4-5, >5 days), previous match outcome (win, loss, and draw), and upcoming opponent relative ranking (weaker, trivial, and stronger) were examined. Mean differences (MD) and effect sizes (ESs) with 90% confidence intervals were reported. There were trivial and insignificant differences by player role, position, or upcoming opponent strength, and small-moderate increases in preseason TL compared with in-season (ES [range] = 0.4-0.9). TLs were lower for MD-1 and higher for MD-5+ (ES [range] = 0.4-1.3) when compared with MD-2-4. External loads (ES = -0.40 ± 0.20) were less after wins compared with losses. TLs are increased in the preseason, when training sessions occur greater than 5 days from a match and after losses. Contextualizing factors affecting TLs has implications for developing workload prescription and recovery strategies.

Polls and Elections: Abandoning the Ground Game? Field Organization in the 2016 Election

I examine the organizational and voter contact strategies of the presidential campaigns in the 2016 election, finding that Hillary Clinton opened many more field offices than Donald Trump. Both Clinton and Trump invested less aggressively in field operations than their predecessors while avoiding areas of opponent strength and “swing” areas. Neither Clinton nor Trump held a clear advantage in voter contact, and estimates of the effects of field offices were smaller than in previous cycles. Clinton's defeat should not be interpreted as evidence that field organizing is a poor investment in 2020.

Running Performance of Soccer Players During Matches in the 2018 FIFA World Cup: Differences Among Confederations.

With the purpose of quantifying the differences in the running performance of soccer players during matches from different continental confederations, data of 1508 match observations generated from 559 players in 59 matches at the 2018 FIFA World Cup held in Russia were analyzed. Generalized mixed linear modeling was carried out to estimate the effect of confederations on each of the selected thirteen match running performance related variables (total distance covered, top speed achieved, number of sprints, distance covered and time spent in walking, jogging, low-speed running, moderate-speed running, and high-speed running), controlling the effects of match result, competition phase, and team and opponent strength. Results showed that the differences in the match running performance of UEFA and CONMEBOL players were trivial (ES between 0.04 and 0.14); players from AFC, CAF, and CONCACAF covered less total distance (ES between 0.26 and 0.54), spent less playing time, and covered less distance in jogging and low-speed running (ES between 0.20 and 0.53), whereas they spent more time walking (ES between 0.27 and 0.41) as compared with players from UEFA and CONMEBOL; top speed achieved, number of sprints made, and time spent and distance covered in the moderate- and high-speed running intensity zones by players from all confederations were similar (ES between 0.01 and 0.15), with an exception that high-speed-running distance covered by CONCACAF players was less than that by CAF players (2.0 ± 1.5 m/min vs. 2.3 ± 1.7 m/min, ES = 0.23, ±90% CL: ±0.21).

The coevolution of transitive inference and memory capacity in the hawk–dove game

Transitive inference (TI) that uses known relationships to deduce unknown ones (using A > B and B > C to infer A > C given no direct interactions between A and C) to assess the opponent's strength, or resource-holding potential (RHP), is widely reported in animals living in a group. This sounds counter-intuitive because TI seems to require social cognition and larger memory capacity than other inference that does not require social cognition as much as TI; individuals need abilities to identify others, observe contests among others and keep the results in memory. We examine the coevolution of memory and transitive inference by the evolutionary simulations, using the asymmetric hawk–dove game. When a cost for losers is higher than a reward for winners, we found that the immediate inference strategy (II), which estimates the opponent's strength based on the past history of the direct fights, evolves with the large memory capacity, while the TI strategy, which estimates the unknown opponent's strength by transitive inference, evolves with the limited memory capacity. When a cost for losers is slightly higher than a reward for winners, the II strategy with the large memory capacity has an evolutionary advantage over the TI strategy with the limited memory capacity. It is because the direct fights are not so costly that more information about the fights leads to more accurate estimation of the opponent's strength and results in the accurate rank of the RHPs. When a cost for losers is much higher than a reward for winners, the TI strategy with the limited memory capacity has an evolutionary advantage. It is because a good way to avoid the costly fights is the prompt formation of the dominance hierarchy which does not necessarily reflect the actual rank of the RHPs; the TI strategy builds the dominance hierarchy much faster than the II strategy regardless of memory capacity, and the large amounts of information are not required for the TI strategy to form the dominance hierarchy promptly. Our study suggests that even smaller memory capacity is evolutionarily favored in TI. The TI strategy tends to reinforce the hierarchy once it is built, regardless of whether it is consistent with RHP or not, because results of direct fights are always counted. Smaller memory capacity allows players to adjust the hierarchy well if it does not represent RHP. These results prove that TI can evolve without a requirement for large memory.

HUBUNGAN TINGKAT KEKUATAN OTOT DENGAN PRESTASI ATLET CABANG OLAHRAGA JUDO PADA PEKAN OLAHRAGA NASIONAL (PON) XVIII 2012 DI RIAU

Judo is described as a physical contact sport. A judo athlete should try to make themovement of throwing, slamming, and holding the opponent's strength during the game. Toperform the technique well, muscle strength is important in judo athlete. As one of thecomponents of physical fitness in athletes, muscle strength has an important role for thejudo athlete to maximize their performance and have their best achievement. Therefore, thisstudy aims to determine the relationship of muscle strength level of judo athlete with theirachievement in Pekan Olahraga Nasional (PON) XVIII 2012 in Riau. A cross-sectionalstudy using analytical method was done on 19 Judo athletes as subjects. Data are collectedfrom secondary data as a result of muscle strength examination measured by push, pull, andleg dynamometer, conducted by Komite Olah Raga Nasional (KONI) West Java. Judoathletes who participated Pekan Olah Raga Nasional (PON) XVIII 2012 championship inRiau were included while athletes who injured were excluded. In this study judo athleteswho won medals (got achievement) was 7 athletes, while those who did not win medals (didnot get the achievement) was 12 athletes. Significance value (p-value) for the relationship ofmuscle strength with judo athletes achievement as measured by push dynamometer was0.764, pull dynamometer was 0.570 and leg dynamometer was 0.132. In conclusion, there isno significant relationship between the level of muscle strength with the judo athletesachievement on Pekan Olah Raga Nasional (PON) XVIII 2012.

경연 네트워크에서 중심성과 승률의 관계

본 연구는 이전에 연구된 적이 없는 경연 네트워크를 대상으로 경연 네트워크의 개념을 정의하고, 경연자의 중심성과 승률의 관계를 탐색적으로 분석하였다. TV 음악 경연 프로그램인 '불후의 명곡'을 대상으로, 총 386명의 경연자가 펼친 1,307회의 경연 결과를 수집하여 경연 네트워크를 구성하였다. 경연자의 중심성과 승률을 산출하여 그들의 관계를 상관분석, 회귀분석, 시각화 등의 방법을 사용하여 분석하였다. 본 연구의 결과를 하면 다음과 같다. 첫째, 경연 네트워크는 멱함수 법칙을 따르는 척도 없는 네트워크이다. 둘째, 경연수와 다른 경연자들과의 친밀도 사이에는 로그함수 관계가 존재한다. 셋째, 경연수가 20회 이상인 경연자의 승률은 대략 60%로 수렴한다. 마지막으로, 경연수가 20회 미만인 경연자의 승률은 대진 운에 23% 정도의 영향을 받는다. 본 연구의 학문적 의의는 경연 네트워크를 최초로 정의하고 탐색함으로써 소셜 네트워크 연구의 새로운 분야를 개척하였다는 점이며, 실행적 의의는 중심성과 승률의 관계에 대한 실증적 패턴을 발견하여 경연 네트워크에서 사회적 관계를 개선하고 승률을 높일 수 있는 방법을 제시하였다는 것이다. We identified a competition network which has never been studied before and investigated the relationship between centrality of participants in singing competition and their winning percentage within the competition network. We collected competition data from 'Immortal Songs: Singing the Legend', which is a Korean television music competition program, and constructed a competition network. We calculated centrality and winning percentage and analyzed their relationship using correlation analysis, regression analysis, and visualization. There are four main findings in this research. First, a competition network is a scale-free network whose degree distribution follows a power law. Second, there is a logarithmic relationship between the count of competition and closeness. Third, winning percentage converges to approximately 60% for players who have participated in more than 20 competitions. Lastly, a strength of opponents affects approximately 23% of winning percentage for players with less than 20 competitions. The academic significance of this study is that we pioneered the definition of the competition network and applied social network analysis method. Another significant contribution of this paper is that we found explicit patterns between the centrality and winning percentage, suggesting ways to improve social relationship in competition network and to increase winning percentage.

POLITICAL PRACTICE WHITE ARMIES IN SIBERIA AND IN THE FAR EAST (1918 - 1920)

Questions of political participation in events of Civil war in Russia of armed groups of anti-Bolshevist forces, in the context of consideration of this major period in the history of the country, are fundamental for judgment of the happened accident. Having become almost only organized force capable to resist to the new arising statehood, the armed strength of opponents of the Soviet power has tried to play the leading role in political practice of white forces. The assessment of the received results allows understanding with big understanding the reasons of defeat of white forces in Civil war in the east of the country. With coming to power of the admiral A.V. Kolchak in east part of Russia the mode which had to represent individual dictatorship was set. However already the first political steps of opponents of the mode have called into question intentions of the power. The ataman G.M. Semenov who sought to head anti-Bolshevist forces in the region became one of the first opponents of the mode. The first attempts of the new power to bridle the ataman haven't brought positive result. Semenov's performance testified to absence of much-needed unity in camp of opponents of Bolsheviks. For counteraction to opponents of the mode the power used military force. Actually the army became the tool in hands of Kolchak who was used for dictatorship support. Army, without having experience of political work, I realized installations of the power. In practice of her activity there were receptions of repressive character: arrests, destruction of property, executions. Such measures, according to the power, had to provide elimination of political opponents of the mode. However the realized actions only shook the power. Crash of the Kolchak mode became a result.

On-field performances of female and male field hockey players – A review

The main purpose of this study was to review a series of studies (N = 23) on on-field performances of female and male field hockey players. Studies were selected from a computerized search in electronic databases (SPORTDiscus, Google Scholar), as well as from a manual search. Among the main findings that emerged from the studies on female players were that (a) the mean distance covered during a game ranged between 5.5-6.6 km, (b) the individual playing time was approximately 48 min, and (c) the average heart rate (HR) was approximately 170 beats·min-1. For the male players, it was found that (a) the total distance covered per playing position for the duration of the game ranged from ∼5,820 m to ∼10,000 m, (b) the players spent most of the time and covered most of the distance while performing low-and moderate-intensity activities, and (c) the players’ HR was over 75% of HRmax for 90% of the game. Among the methodological and measurement concerns discussed in the article are: the variation in the selection of different locomotion categories, the lack of data on game results and opponent strength, and the presentation of data per individual player and/or per playing position.

Adjusted Plus-Minus for NHL Players using Ridge Regression with Goals, Shots, Fenwick, and Corsi

Regression-based adjusted plus-minus statistics were developed in basketball and have recently come to hockey. The purpose of these statistics is to provide an estimate of each player's contribution to his team, independent of the strength of his teammates, the strength of his opponents, and other variables that are out of his control. One of the main downsides of the ordinary least squares regression models is that the estimates have large error bounds. Since certain pairs of teammates play together frequently, collinearity is present in the data and is one reason for the large errors. In hockey, the relative lack of scoring compared to basketball is another reason. To deal with these issues, we use ridge regression, a method that is commonly used in lieu of ordinary least squares regression when collinearity is present in the data. We also create models that use not only goals, but also shots, Fenwick rating (shots plus missed shots), and Corsi rating (shots, missed shots, and blocked shots). One benefit of using these statistics is that there are roughly ten times as many shots as goals, so there is much more data when using these statistics and the resulting estimates have smaller error bounds. The results of our ridge regression models are estimates of the offensive and defensive contributions of forwards and defensemen during even strength, power play, and short handed situations, in terms of goals per 60 minutes. The estimates are independent of strength of teammates, strength of opponents, and the zone in which a player's shift begins.

Social control of unreliable signals of strength in male but not female crayfish,Cherax destructor

The maintenance of unreliable signals within animal populations remains a highly controversial subject in studies of animal communication. Crustaceans are an ideal group for studying unreliable signals of strength because their chela muscles are cryptically concealed beneath an exoskeleton, making it difficult for competitors to visually assess an opponent's strength. In this study, we examined the importance of social avenues for mediating the possible advantages gained by unreliable signals of strength in crustaceans. To do this, we investigated the factors that determine social dominance and the relative importance of signalling and fighting during aggressive encounters in male and female freshwater crayfish, Cherax destructor. Like other species of crayfish, we expected substantial variation in weapon force for a given weapon size, making the assessment of actual fighting ability of an opponent difficult from signalling alone. In addition, we expected fighting would be used to ensure that individuals that are weak for their signal (i.e. chela) size would not achieve higher than expected dominance. For both male and female C. destructor, we found large variation in the actual force of their chela for any given weapon size, indicating that it is difficult for competitors to accurately assess an opponent's force on signal size alone. For males, these unreliable signals of strength were controlled socially through increased levels of fighting and a decreased reliance on signalling, thus directly limiting the benefits accrued to individuals employing high-quality signals (large chelae) with only low resource holding potential. However, in contrast to our predictions, we found that females primarily relied on signalling to settle disputes, resulting in unreliable signals of strength being routinely used to establish dominance. The reliance by females on unreliable signals to determine dominance highlights our poor current understanding of the prevalence and distribution of dishonesty in animal communication.

Female–female aggression: structure of interaction and outcome in loggerhead sea turtles

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 336:267-274 (2007) - doi:10.3354/meps336267 Female–female aggression: structure of interaction and outcome in loggerhead sea turtles Gail Schofield1,2,*, Kostas A. Katselidis1,3, John D. Pantis4, Panayotis Dimopoulos1, Graeme C. Hays2 1Department of Environmental & Natural Resources Management, University of Ioannina, G. Seferi 2, 30100 Agrinio, Greece 2Department of Biological Sciences, Institute of Environmental Sustainability, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK 3National Marine Park of Zakynthos, 1 El. Venizelou Street, 29100 Zakynthos, Greece 4Department of Ecology, School of Biology, UP Box 119, Aristotle University of Thessaloniki, 54006 Thessaloniki, Greece *Email: g.schof@freemail.gr ABSTRACT: Aggressive behaviour between females of the same species is not widely documented, particularly in marine vertebrates. During a 3 yr in-water survey at the temperate loggerhead sea turtle Caretta caretta breeding area of Zakynthos, Greece, female–female interactions comprised 4% of all female loggerhead sighting events (n = 60 out of 1449 events). Male–female interactions comprised an additional 4% of sighting events, while 92% were of solitary females. The structure of interactions was analysed for 58 of these sighting events, each lasting an average of 3.4 min (SD ± 1) and comprising a total of 3.1 h observation time. We found that interactions involved ritualized escalation in behaviour from passive threat displays (e.g. head–tail circling) to aggressive combat (e.g. sparring). We suggest that circling individuals evaluate opponent size, sparring individuals test opponent strength, and that the positioning of the prehensile tail signals motivational intent to either escalate or abort. The presence of intruder females triggered a passive response in 100% of events involving basking and swimming turtles (n = 19); although residents resting on the seabed only responded on 69% of occasions (n = 27), their response was almost 4 times more likely to escalate to one of aggression. Our results suggest that certain sites may be preferentially sought after and defended by sea turtles. KEY WORDS: Caretta caretta · Sequential assessment · Evolutionary stable strategy · Territory · Marine · Vertebrate · Reptile Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 336. Online publication date: April 27, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Football Rating Systems for Top-Level Competition: A Critical Survey

Comprehensive rankings of football teams have become an important, and occasionally controversial, feature of many football codes. The rationale behind these systems needs to be understood. The historical evolution of the current eight codes is briefly traced from just two: association football and rugby football, played under various forms in the mid 19th century. Based on current rules, the eight codes fall into four groups: first, Australian Rules football and Gaelic football; second, American college football, American professional football and Canadian football; third, rugby union and rugby league; and fourth, soccer. Comprehensive rating systems exist for three codes. For American college football, the Bowl Championship Series or BCS system places top US college football teams into a national championship game and other important "bowl games". That system combines two normally incompatible components, an objective adjustive computer component and a subjective human-poll component. The composite has been controversial in four of the nine years of service, when the computer component differed from the human component resulting in major changes that favored the human component each time. For rugby union, the International Rugby Board or IRB system employs a predictor/corrector adjustment in which defeating a weak team provides less gain than defeating a strong team while losing to a weak team elicits a much larger negative adjustment than losing to a strong team, arguably a fair and efficient methods for rating competitors. For soccer, FIFA have improved the previous rating systems with a new and simpler system which takes into account strength of opponents and game importance; however, all losses are treated as equal regardless of the opponents, and home advantage is ignored. An Elo based system, employing many of features of the IRB system, appears to have advantages over the FIFA system.