Significant Relative Age Effect Research Articles

Maturity Status and Relative Age of Elite Taekwondo Youth Competitors-Case Study on Croatian National Team.

This study examines the maturity status and relative age effect in elite youth taekwondo Croatian National Team athletes. Measurements of biological age, maturity offset, and body composition were taken from a sample of 17 junior athletes. Differences in maturity status were observed among athletes of the same chronological age, with variations in sitting height and age at peak height velocity. Male athletes generally exhibited higher values in body height, percentage of body fat, muscle mass, and total body water. No significant relative age effect was found. These findings highlight the importance of considering individual biological age and maturity status for talent development and training program adjustments. Further research involving athletes from different countries is recommended to validate these results and enhance the understanding of youth taekwondo athlete development.

The Relative-Age Effect in Male Japanese Football: A CrossSectional Analysis from Youth to Senior Competitive Level

The objective of this study was to examine the magnitude and persistence of the Relative-Age Effect (RAE) in competitive Japanese youth and senior football. A cross-sectional analysis of birthdate distributions of Japanese male youth academy football players (n= 4,488) from the U12 (n=268), U13 (n=481), U14 (n=464), U15 (n=483), U18 (n=1059) and professional players (n=1733) in the 2022 season was conducted. Chi-square goodness of fit tests and Cramer’s V tests were carried out to reveal the incidence and effect size of the RAE across the age categories. A significant RAE (P< .001) was found. It became more pronounced with age, peaking in the U18 age group (Cramer's V= 0.436; Q1/Q4 OR 6.04) before declining in senior professional players (Cramer's V= 0.204; Q1/Q4 OR=2.23). The organisation of youth competition in Japan, with a transition from annual age groups up to U15 to the U18 age group representing three years (U16, U17, and U18) appears to increase the selection bias towards early born players to the detriment of those born later in the age group. However, the transition to senior football saw, compared with the U18 proportions, a reduced proportion of Q1 players, a very similar proportion of Q2 players and increased proportions of Q3 and particularly Q4. The clear implication is that a Q3 and Q4 youth player represents a better prospect for senior professional football than Q1 or Q2 and Q2 than Q1.

Relative age effect across the talent identification process of youth female soccer players in the United States: Influence of birth year, position, biological maturation, and skill level.

The aims of the study were to examine the relative age effect (RAE) in youth female soccer players in the United States (US) and the influence of birth year, playing position, estimated maturation and skill ratings. The sample consisted of 3,364 youth female soccer players who were active in the 2021-2022 US soccer season across three main stages of the talent identification (TID) process for Youth National Team (YNT) players (i.e., Club, TID Center, and YNT). A prevalent RAE for players born in Q1 was present in the full sample. A significant prevalence for Q1 players were identified for both Club and TID Center, but not YNT. A significant RAE prevalence for Q1 players was identified for most of the age groups from U13-U18 at Club (except U18) and TID Center (except U17). Significant RAEs prevalence for players born in Q1 were found in Goalkeepers, Center Backs, Midfielders, and Center Forwards at Club and TID Center (except Wide Forwards). The data identified a consistent RAE prevalence for Q1 players in early and on-time-maturers across all levels. An even birthdate spread was evident in YNT with a prevalence for Q4 players and a higher percentage of late-maturers than elsewhere in the TID process. Results reinforce evidence indicating RAEs still exist in soccer, yet show for the first time within a youth female soccer TID process, the influence of contextual factors on the prevalence of RAE. This information can be used to advance TID and development across the US soccer landscape.

The Relative Age Effect of Participants in the World Junior Tennis Finals in 2012–2016

The main aim was to verify the Relative Age Effect (RAE) between female junior tennis players (U14, n=240), participants of the World Junior Tennis Finals in 2012–2016. The secondary aim was to verify the RAE on the order of nomination to each national team and then verify the RAE on the final ranking of the teams. The third aim was to compare the RAE between junior female tennis players and the world's best senior female players. Chi-square test and Effect Size (ES) index w were used for statistical data analysis. Statistically significant RAE was found in each of the years 2012–2016 for all subgroups, ES ranged between medium and large. Statistically significant RAE was found for all female players over the entire five-year period, ES was medium. Statistically significant RAE was found in all cases for nominations of players (the first, second and third tennis player of team), ES ranged between medium and large. In all four performance groups (1st-4th, 5th-8th, 9th-12th, 13th-16th), the RAE was statistically significant, ES was medium and large. Comparison of RAE between the groups of junior tennis players and the world's best players showed non-significant differences, the ES was small. Keywords: Date of birth. Chronological age. Age distribution. Youth sports. Sports.

The Relative Age Effect at Different Age Periods in Soccer: A Meta-Analysis.

In the selection of young athletes, earlier-born adolescents often leverage their temporary biological advantage over their later-born peers from the same cohort, giving rise to the phenomenon known as the Relative Age Effect (RAE). In this study, we delved into the complexities of the RAE in soccer by reviewing 563 independent research samples across 90 articles. Our analysis showed that age period and performance level are pivotal factors influencing the magnitude of the RAE. The adolescent age period emerged as a significant RAE determinant, showcasing the highest effect size magnitudes in our findings. Among athletes of different performance levels, adult European soccer players have been extensively studied, and they have exhibited the most pronounced RAE magnitudes. Intriguingly, our findings reveal another compelling trend: the frequency of players born early versus late in the eligible birth year escalated as player performance levels increased, particularly during adolescence. Coaches and players appear to capitalize unconsciously on this maturational advantage, though this strategy wanes post-adolescence. While there are currently no penalties for this team selection practice, our findings stress the need for coaches to comprehend the ramifications of selecting athletes with an age bias We offer insights into RAE complexities, highlight the synergy of age and performance in these transitory advantages, and advance arguments for more fairly selecting and developing youth athletes.

Relative Age Effects in The Selection of Representative Athletes of Kosovo National Team in Handball, Football, Basketball, Volleyball - Post Puberty Age

Taking into account the role that the selection of athletes has in the success of clubs as well as in the sports life of young people, this research aims to highlight the impact of the Relative Age Effects (RAE) in the selection of athletes for representative teams of Kosovo in collective sports and the difference between the respective groups. The study was designed as an observational cross-sectional study. The total sample of persons in this research was n=237 (118 male and 119 female) athletes of the Kosovo National Team of team sports. The athletes were divided into 4 main groups: Q1 (January-March), Q2 (April-June), Q3 (July-September) and Q4 (October-December) with a special emphasis on the Q1 and Q4 group (for all sports the birth dates of the age post-puberty were collected). The analysis of the data clearly indicates that young athletes born in Q1 and Q2 were significantly more selected for representative teams compared to those in the other two groups. The results demonstrate a significant relative age effect on athlete selection based on gender for the Kosovo National Team. Specifically, athletes from Q1 and Q2 were favored. Based on these findings, it is strongly recommended that the respective federations, sports trainers, and relevant sports authorities take proactive measures to prevent the “discrimination” experienced by young athletes.

Forever young: Relative age effects in Belgian political selection

AbstractPolitical selection is crucial for the functioning of democracy. However, the practice—in education and sports contexts—of artificially dividing school‐age children into different age groups leads to a considerable bias in this selection. The probability of becoming a (successful) politician depends on individuals' relative age. Being born shortly after the cut‐off date significantly increases the probability that an individual will be politically successful later in life. Using a regression discontinuity design, we find strong evidence of such relative age effect (RAE) among a large sample of Belgian federal parliamentarians over the period 1950–2019 (N = 4032), but not among municipal councillors (N = 7387), nor among municipal candidates (N = 36,740) in the 2018 election. The estimated overrepresentation of federal members of the parliament (MPs) born immediately after the cut‐off date is up to 90% compared to politicians born just before the cut‐off date. The overrepresentation is observed over the whole period and thus seems to be deeply rooted in the political system. We find the RAE to have a gendered dimension: The effect is driven by early‐born male politicians' overrepresentation. No significant RAE was found among female politicians.

Relative age effect

The aim of this study was to examine relative age effect (RAE) on distinctive variables and age groups in recreational football. Participants (N = 79,249) included male (n = 63,540) and female (n = 15,709) players aged 2 to 12 years. Data were gathered through an official database containing all licensed players in Denmark. Birthdate distributions were split by age category, sex, club size, year group size, and birth quarter (Q1 = January to March, Q4 = October to December). RAEs were calculated using chi-square analysis. Significant RAEs existed in all age categories (except females in U6 and below). The effect was most pronounced at the entry level among both males and females. Club size was not associated with RAEs, but were shown in smaller and midsized year groups, but were absent in larger year groups. The results of this study show that RAEs are present from early sport participation.

The relative age effect shifts students' choice of educational track even within a school system promoting equal opportunities.

In most education systems, the age of a given cohort of students spans up to 12 months, which creates a within-class age difference, or relative age effect, that tends to disadvantage younger students. Because birth month indeed correlates with academic performance, with poorer outcomes for students born later in the year, the effect can have lifelong consequences for students, whose academic performance justifies their acceptance into different educational tracks. Although past studies have identified the relative age effect in students' choice of educational track in school systems in which students make such choices at the age of 10-14 years, we examined data from the Norwegian school system, in which education tracks are chosen at the age of 15-16 years. The dataset included the variables birth month, track choice, and gender, of all 28,231 pupils at the upper secondary school level in a school county in Norway. Birth month was compared between vocational and academic track choices and the results revealed a significant relative age effect on educational choices between academic and vocational tracks, such that younger students were significantly more likely to apply for vocational tracks. The effect was significantly stronger for boys compared to girls. This indicates that the choice of educational track may reflect students' relative age, especially among boys, and hence, not be based on interests alone. Those findings have implications for actors involved in ensuring equity in education systems in Norway and elsewhere.

Relative age effect in young competitive tennis players

The purpose of this study was to examine the presence of the relative age effect (RAE) in young tennis players. Data from a sample of all ranked (n= 3463) and licensed (n= 29150) players in consecutive age groups (10- to 17-year-old) were collected from the official web page of the national federation. They were assigned to four quartiles according to the month of birth: a) Quartile 1 = January-February-March, b) Quartile 2 = April-May-June, c) Quartile 3 = July-August-September, d) Quartile 4 = October-November-December. The players aged between 10 and 17 years affiliated with the national federation were assigned as theoretically expected distribution. The results revealed that 70%, 60.1%, and 56.6% of the top 10, 50, and all ranked players were born in the first half of the year, respectively. However, the results from the chi-square test of goodness-of-fit showed significant RAEs only in the distributions of all ranked and top 50 players at the age of 10 and 11 correspondingly. These results may suggest that RAE exists among young tennis players who are in their early adolescence years.

The relative age effect in top 100 elite female tennis players in 2007-2016.

The Relative Age Effect (RAE) has been the subject of many studies, but few have focused on professional athletes in individual sports. The aim of this study was to verify the existence of the RAE among elite senior female tennis players (top 100 players) in the WTA Rankings (n = 1000) in the years 2007-2016. The analysis was performed among top 100, resp. top 10 female tennis players, among players in 4 age subgroups and among left-handed (LH) and right-handed (RH) players. The existence of the RAE was assessed with the use of chi-square test (goodness of fit). More than half of top 100 players were born in first semester: both in individual years (53.0-63.0%) and in the whole observed period (58.4%). Significant RAE (ES medium) was observed in top 100 female players only in 2012 and 2016; significant RAE (ES small) was detected in the period of 2007-2016. Among the top 10 players, significant RAE (ES medium) was demonstrated during the whole period. No significant RAE (ES medium) was detected in the 17-18y subgroups, significant in 19-24y and 25-30y (ES small) as well as in 31-36y (ES medium). Although significant RAE was observed in the subgroups of LH and RH female players, ES was large only in the LH. The results contribute to the expansion of the knowledge about the reduction of the RAE existence in adulthood among coaches, athletes and tennis officials.

Relative Age Effect in Senior Football Leagues in Former Yugoslav Republics

The relative age effect is considered to be the main cause of the uneven distribution of birthdates in sports teams, particularly in football. The aim of this paper is to examine the presence of the relative age effect in the leagues of the former Yugoslav republics and the differences in birthdates distribution between the leagues. To test hypoth- eses, we used publicly available information obtained from official websites, which regarded players who played in the analyzed leagues during the 2020/2021 season. The absolute results indicate that in five of the six observed leagues, the greatest number of players were born in the first quartal of the year. A more detailed observation of each league individually found a significant relative age effect among players who play in the Serbian, Croatian and Slovenian leagues, but not in Northern Macedonia, Montenegro, and Bosnia, and Herzegovina. Also, the re- sults show that the quarterly distribution of analyzed leagues does not differ significantly. The results of this paper should serve the purpose of raising awareness about the presence of the relative age effect in regional football. All this should affect the creation of an environment in which all football players would have an equal chance for development and progress, reduce the chances of overlooking potential talents and ultimately raise the quality of football in the region.

Low prevalence of relative age effects in Luxembourg's male and female youth football.

The relative age effect (RAE) is a well-established phenomenon in football. However, while the majority of previous studies focussed on established football nations, it remains unclear if the constraint of a limited population of soccer players in smaller countries associated with less strict selection procedures may reduce the risk of RAE. This study aims to investigate the RAE in Luxembourg that follows an 'open-door' selection policy in youth football due to the limited pool of players. Birthdates from all licensed and actively playing Luxembourgish youth footballers including all players of the youth national teams (396 girls and 10981 boys) competing in the season 2018/2019 were analysed and categorised into birth quarters and semesters. To further investigate a performance dependence of the RAE in amateur leagues, success was determined based on the teams' rankings at the end of the season. Differences between observed and expected birthdate distributions were calculated across all licensed players and age groups, within the national teams, and for the top- and bottom-tier football teams using chi-square statistics. While a RAE was absent across all age groups (except U7), significant RAEs with high effect sizes were observed in the top-level and national teams. These findings contrast the substantial RAE effects in large football nations and suggest that open selection systems might reflect an environmental constraint that limit the prevalence of RAE in football. Further, this study indicates that a performance dependence of the RAE is not limited to high level football but already occurs on an amateur level.

Are Soccer and Futsal Affected by the Relative Age Effect? The Portuguese Football Association Case.

A better understanding of the relative age effect (RAE) in youth will increase the awareness of the need for reducing the bias of (de)selection. Thus, we investigated the RAE in youth female and male soccer and futsal players in Portugal, using nationwide data. Birthdates of 5,306 female and 126,285 male soccer players, and 2,437 female and 23,988 male futsal players (U7–U19), registered in Portugal during the season 2019–2020, and Portuguese National teams (from U15 to AA soccer teams and from U17 to AA futsal teams) were analyzed. Data were categorized into age groups and certification levels [no certification, basic football training center, football school, and training institution] of the respective clubs/academies. Birthdates were stratified from the start of the selection year using quartiles (Q) and semesters (S). Differences between the observed and expected birthdate distributions were analyzed using chi-square statistics, and RAEs were calculated using odds ratios (OR). In both soccer and futsal, female players, in the age category U9, RAEs were found (Q1 vs. Q4, OR: 1.49 and 1.84, respectively). In male soccer, differences in the birthdate distribution were observed in all age categories (U7–U19) with significant OR between all comparisons (Q and S). In contrast, an over-representation of young male futsal players (Q1 vs. Q4) was observed only in the age categories U7 and U9 (OR: 1.54 and 1.34, respectively). The stratification by certification level showed a significant RAE for all certification levels in male soccer players. In contrast, in male futsal players, the RAE was significant only in clubs and academies with the highest level. For National teams, the RAE was more pronounced in male soccer, particularly in the U16 and U17 (OR: 9.84 and 12.36, respectively). Data showed a RAE in female and male youth soccer and futsal, particularly in male, younger age categories, and in clubs and academies having a higher certification level, which could be accompanied by a loss of valuable elite players during the youth phase of their careers. Thus, adjustments in the systems and structure of talent identification are recommended to prevent RAE-related discrimination in youth soccer and futsal.

Relative Age Effect in Elite German Soccer: Influence of Gender and Competition Level.

The relative age effect (RAE) is associated with (dis)advantages in competitive sports. While the RAE in elite male soccer reveals a skewed birthdate distribution in relation to a certain cut-off date, research of RAE in elite female soccer is affected by small number of samples and conflicting results. The purpose of this study was to investigate the RAE in elite adult German soccer regarding gender and competition level. The sample comprised 680 female and 1,083 male players of the two top German leagues during the 2019/20 season and German national teams (A-Team to Under 19). Differences between the observed and expected birthdate distributions were analyzed using chi-square statistics and effect sizes followed by calculating odds ratios. Results showed a statistically significant RAE with small effect size across all players included for both genders (female players: P < 0.001, W = 0.16, male players: P < 0.001, W = 0.23). The identified RAE was based on an over-representation of players born at the beginning of the year. According to gender and competition level, RAEs were more pronounced in German male soccer. While significant RAEs were found among males in the first two leagues (first league: P < 0.001, W = 0.19, second league: P < 0.001, W = 0.26), the RAE of females was more pronounced in the second league (first league: P = 0.080, W = 0.16, second league: P = 0.002, W = 0.20). The analysis of RAE regarding the national teams revealed a statistically significant RAE with large effect size for only the youngest investigated age group of male players (Under 19: P = 0.022, W = 0.52). Our data show an RAE in female and male German adult soccer, which could be accompanied by a loss of valuable elite players during the youth phase of the career. Consequently, the pool of talented players at the adult level would be limited.

Are European Soccer Players Worth More If They Are Born Early in the Year? Relative Age Effect on Player Market Value.

The relative age effect (RAE) consists of the lower presence of members of an age group born in the months furthest from the age cut-off date established. In youth soccer, it is known that because of this effect the birth dates of more players in a team are closer to the cutoff of 1 January. These older players, due to their physical and psychological advantages, are more likely to be identified as talent. This study aimed to examine whether RAE can be identified in professional players of the top five European soccer leagues (Spain, Italy, England, Germany, and France) and to assess its influence on the perceived market value of the players. Market value data for 2577 players were obtained from the Transfermarkt database. A significant RAE was produced in all leagues (p < 0.05). However, this bias did not affect the market value of the professional elite soccer players examined here. Our observations indicate that, while the identification and promotion of talent at young ages are often biased by RAE, once players have reached the professional stage, the market value assigned to them is based more on factors other than their date of birth.

Did the Relative Age Effect Change Over a Decade in Elite Youth Ski Racing?

The relative age effect (RAE) represents an asymmetry in birth quarter distribution, favoring athletes born early in the selection year and discriminating against late born athletes. The RAE was proven to be present in all age categories of national and international levels of alpine ski racing. Due to the existence of the RAE in all categories, it can be assumed that a selection error takes place favoring early born and early maturing youth ski racers. However, whether selection strategies have changed during the last years due to the high amount of research done in this field, has not been investigated so far in this sport. Therefore, the aim of the present study was to assess whether the magnitude of the RAE in youth ski racers aged 10–14 years has changed during the last decade by comparing the periods 2005–2009 (“former” athletes) and 2015–2019 (“current” athletes). Pupils of a well-known skiing-specific secondary modern school as well as members of the provincial ski team, who all competed at national levels, were included in the study. Next to the birth months, anthropometric characteristics (body height, weight, body mass index) were assessed. Chi-square tests were used to compare differences between the observed and expected relative age quarter distributions across five age categories (U11–U15). Additionally, Kruskal–Wallis-H-Tests were performed to assess differences in anthropometric characteristics between athletes of the four relative age quarters. Mann–Whitney U-Tests were performed to assess possible differences in anthropometric characteristics between former and current ski racers. A highly significant RAE was present in both former [χ2(3, 764) = 60.36; p < 0.001; ω = 0.31] and current youth ski racers [χ2(3, 702) = 43.13; p < 0.001; ω = 0.29] with an over-representation of athletes of Q1 (30.3–34.2%) and a clear under-representation of athletes of Q4 (14.8–15.0%). Generally, results indicated no change in the magnitude of the RAE in youth alpine ski racing over the past 10–15 years, emphasizing the robust nature of this phenomenon. No significant differences were found in any of the anthropometric characteristics between athletes of the four relative age quarters in both former and current athletes, indicating that relatively younger athletes of the last relative age quarter seem to have to have advanced anthropometric characteristics for being selected. Changes in the talent selection process should be performed to reduce the impact of the RAE.

Characteristics of Relative Age Effects and Anthropometric Data in Japanese Recreational and Elite Male Junior Baseball Players

BackgroundThe mechanisms underlying the relative age effect (RAE), a biased distribution of birth dates, in sport events have been investigated for more than two decades. The present study investigated the characteristics of the RAE in baseball and anthropometric data (height and weight) among recreational junior baseball players as well as elite players, using data extracted from national surveys.MethodsBirth and anthropometric data were obtained from 4464 Japanese students as elementary school, junior high school, and high school players.ResultsSignificant RAEs were noted in recreational junior high school and high school players, but not in elementary school players, and the effect size became larger with increasing grade (0.063 in elementary school players, 0.151 in junior high school players, and 0.227 in high school players). We also observed a significant RAE for elite elementary, junior high, and high school players. However, the effect size of elite players became smaller with increasing grade (0.563 in elementary school players, 0.358 in junior high school players, and 0.343 in high school players). Height and weight values were significantly larger in elite elementary and junior high school players than in recreational elementary and junior high school players, but height was almost the same between recreational and elite high school players.ConclusionThe characteristics of RAEs differed between recreational and elite junior baseball players. Anthropometric data were also different, depending on birth data, and between recreational and elite baseball players in elementary and junior high school students.

Relative Age Effect and the Re-Selection of Danish Male Handball Players for National Teams.

The relationship between the date of birth and expertise in various sports among both elite and youth level athletes is well established, and known as the relative age effect (RAE). However, new results in for example Canadian Hockey and British cricket and rugby have indicated a reversal of RAE among selected talents where the youngest athletes are more likely to remain selected than their older peers. As such, RAE may therefore depend on the age and the level of competition. The purpose of this study was therefore to analyse RAE from the youth to senior national level in a sample of successful Danish male national teams. The sample included 244 players from Danish under-19, under-21 and senior national levels. These players have been part of successful teams, winning 18 medals at 24 youth European and World championships and 8 medals during 12 years at the senior level. The results showed a significant RAE on both youth and national levels. However, RAE was less marked from the under-19 to under-21 and further to the senior national level. Results show that at the national youth level talent selection favours the relatively older players, of whom a larger proportion fails to be re-selected to the senior level compared to their younger peers. RAE appears to play a central and reversing role in the identification and re-selection in Danish male handball. The results also show that the presence of both a constant and constituent year structure affects RAE, even when introduced at late adolescence.

Maturity status influences the relative age effect in national top level youth alpine ski racing and soccer.

Since the relative age effect (RAE) characterizes a problem in all age categories of alpine ski racing and soccer and the fact that, yet, to date the underlying factors have not been well investigated, the aim of the present study was to assess the influence of the biological maturity status on the RAE among youth alpine ski racers (YSR) and soccer players (SP).In total, 183 male and female YSR selected for national final races and 423 male SP selected for Elite Youth Development Centres were investigated. Additionally, a comparison group of 413 non-athletes was evaluated. The birth months were split into four relative age quarters. The biological maturity status was assessed by the age at peak height velocity (APHV) method; according to the M±SD of the comparison group, the athletes were divided into normal, early and late maturing. Chi2-tests indicated a significant RAE among YSR (χ2(3,N = 183) = 18.0; p<0.001; ω = 0.31) and SP (χ2(3,N = 423) = 33.1; p<0.001; ω = 0.28). In total, only a small number of late maturing athletes were present (0.5–2.3%). Among relatively younger athletes, high percentages of early maturing athletes were found (43.1–43.3%).The findings indicate that relatively younger and less mature athletes are marginalized or totally excluded in alpine ski racing and soccer. Thus, selection criteria in both sports are effectively based on early biological development and relatively older age, both of which should be considered in future in the talent selection process. In this context, the easy feasible method of assessing the APHV can be used.