relative age effect

Youth sport participation is often organized into annual age-groups. The IOC,{{Cite web|date=29 July 2021|title=Olympic Documents - Athletes, Olympic Games, IOC and More|url=http://www.olympic.org/Documents/Reference_documents_Factsheets/The_Youth_Olympic_Games.pdf}} FIFA{{Cite web|url=http://www.fifa.com/mm/document/tournament/competition/01/95/44/82/regulationsfu20wcturkey2013%5fee.pdf|title=FIFA.com|archive-url=https://web.archive.org/web/20130330161133/http://www.fifa.com/mm/document/tournament/competition/01/95/44/82/regulationsfu20wcturkey2013%5fee.pdf|access-date=8 November 2021|archive-date=2013-03-30}} and the six international football confederations (AFC, CAF, CONCACAF, CONMEBOL, OFC and UEFA{{Cite web|url=https://www.uefa.com/MultimediaFiles/Download/Regulations/competitions/Regulations/01/65/31/62/1653162_DOWNLOAD.pdf|title=|website=UEFA|access-date=8 November 2021|archive-date=21 June 2018|archive-url=https://web.archive.org/web/20180621143622/https://www.uefa.com/MultimediaFiles/Download/Regulations/competitions/Regulations/01/65/31/62/1653162_DOWNLOAD.pdf|url-status=dead}}) all use 1 January as their administrative cut-off which is most commonly used but, 1 September is used in the UK,{{Cite journal|last1=Cobley|first1=Stephen|last2=Baker|first2=Joseph|last3=Wattie|first3=Nick|last4=McKenna|first4=Jim|date=2009|title=Annual age-grouping and athlete development: a meta-analytical review of relative age effects in sport|url=https://pubmed.ncbi.nlm.nih.gov/19290678/|journal=Sports Medicine (Auckland, N.Z.)|volume=39|issue=3|pages=235–256|doi=10.2165/00007256-200939030-00005|issn=0112-1642|pmid=19290678|s2cid=32633686}} like many other locations around the world.{{Cite journal|last1=Wattie|first1=Nick|last2=Cobley|first2=Stephen|last3=Baker|first3=Joseph|date=2008|title=Towards a unified understanding of relative age effects|url=https://pubmed.ncbi.nlm.nih.gov/18825541/|journal=Journal of Sports Sciences|volume=26|issue=13|pages=1403–1409|doi=10.1080/02640410802233034|issn=0264-0414|pmid=18825541|s2cid=11241958}} This grouping can be seen in the first graph showing the distribution of births, by month, for the European Union over the ten years from 2000 to 2009. The birth rate correlates closely with the number of days in a month with a slight increase in the summer months. The second graph, by the month, shows the birth distribution of over 4,000 players involved in the qualifying squads for U17, U19 and U21 tournaments organised by UEFA in 2010–11.

This declining distribution from the beginning of the year for professional athlete participation has been seen in sports like: association football,{{Cite journal|last1=Ashworth|first1=John|last2=Heyndels|first2=Bruno|date=1 August 2007|title=Selection Bias and Peer Effects in Team Sports: The Effect of Age Grouping on Earnings of German Soccer Players|url=https://doi.org/10.1177/1527002506287695|journal=Journal of Sports Economics|language=en|volume=8|issue=4|pages=355–377|doi=10.1177/1527002506287695|s2cid=154330153|issn=1527-0025|url-access=subscription}} baseball,{{Cite journal|last1=Herring|first1=Chad H.|last2=Beyer|first2=Kyle S.|last3=Fukuda|first3=David H.|date=2021|title=Relative Age Effects as Evidence of Selection Bias in Major League Baseball Draftees (2013–2018)|url=https://journals.lww.com/nsca-jscr/Abstract/2021/03000/Relative_Age_Effects_as_Evidence_of_Selection_Bias.9.aspx|journal=The Journal of Strength & Conditioning Research|language=en-US|volume=35|issue=3|pages=644–651|doi=10.1519/JSC.0000000000003951|pmid=33470599|s2cid=231651477|issn=1064-8011|url-access=subscription}} cricket,{{Cite journal|last=Edwards|first=S.|date=1994-07-21|title=Born too late to win?|journal=Nature|volume=370|issue=6486|pages=186|doi=10.1038/370186a0|issn=0028-0836|pmid=8028664|bibcode=1994Natur.370..186E|s2cid=5420946|doi-access=free}} gymnastics,{{Cite journal|last=Baxter-Jones|first=A. D.|date=1995|title=Growth and development of young athletes. Should competition levels be age related?|url=https://pubmed.ncbi.nlm.nih.gov/7481282/|journal=Sports Medicine (Auckland, N.Z.)|volume=20|issue=2|pages=59–64|doi=10.2165/00007256-199520020-00001|issn=0112-1642|pmid=7481282|s2cid=45304762}} handball,{{Cite journal|last1=Rubia|first1=Alfonso de la|last2=Bjørndal|first2=Christian Thue|last3=Sánchez-Molina|first3=Joaquín|last4=Yagüe|first4=José María|last5=Calvo|first5=Jorge Lorenzo|last6=Maroto-Izquierdo|first6=Sergio|date=2020|title=The relationship between the relative age effect and performance among athletes in World Handball Championships|journal=PLOS ONE|volume=15|issue=3|pages=e0230133|doi=10.1371/journal.pone.0230133|issn=1932-6203|pmc=7098603|pmid=32214322|bibcode=2020PLoSO..1530133R|doi-access=free}} ice hockey,{{Cite journal|last1=Addona|first1=Vittorio|last2=Yates|first2=Philip A.|date=15 October 2010|title=A Closer Look at the Relative Age Effect in the National Hockey League|url=https://www.degruyter.com/document/doi/10.2202/1559-0410.1227/html|journal=Journal of Quantitative Analysis in Sports|language=en|volume=6|issue=4|doi=10.2202/1559-0410.1227|s2cid=120240341|issn=1559-0410|url-access=subscription}} rugby league,{{Cite journal|last1=Till|first1=K.|last2=Cobley|first2=S.|last3=Wattie|first3=N.|last4=O'Hara|first4=J.|last5=Cooke|first5=C.|last6=Chapman|first6=C.|date=2010|title=The prevalence, influential factors and mechanisms of relative age effects in UK Rugby League|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0838.2009.00884.x|journal=Scandinavian Journal of Medicine & Science in Sports|language=en|volume=20|issue=2|pages=320–329|doi=10.1111/j.1600-0838.2009.00884.x|pmid=19486487|s2cid=33840698|issn=1600-0838}} running,{{Cite journal|last1=Romann|first1=Michael|last2=Cobley|first2=Stephen|date=6 April 2015|title=Relative Age Effects in Athletic Sprinting and Corrective Adjustments as a Solution for Their Removal|journal=PLOS ONE|language=en|volume=10|issue=4|pages=e0122988|doi=10.1371/journal.pone.0122988|issn=1932-6203|pmc=4386815|pmid=25844642|bibcode=2015PLoSO..1022988R|doi-access=free}} skiing,{{Cite journal|last1=Romann|first1=Michael|last2=Fuchslocher|first2=Jörg|date=1 April 2014|title=Survival and Success of the Relatively Oldest in Swiss Youth Skiing Competition|url=https://doi.org/10.1260/1747-9541.9.2.347|journal=International Journal of Sports Science & Coaching|language=en|volume=9|issue=2|pages=347–356|doi=10.1260/1747-9541.9.2.347|s2cid=144244440|issn=1747-9541|url-access=subscription}} swimming, tennis,{{Cite journal|last1=Ulbricht|first1=Alexander|last2=Fernandez-Fernandez|first2=Jaime|last3=Mendez-Villanueva|first3=Alberto|last4=Ferrauti|first4=Alexander|date=2015|title=The Relative Age Effect and Physical Fitness Characteristics in German Male Tennis Players|journal=Journal of Sports Science & Medicine|volume=14|issue=3|pages=634–642|issn=1303-2968|pmc=4541129|pmid=26336351}} and the Youth Olympic Games,{{Cite journal|last1=Raschner|first1=Christian|last2=Müller|first2=Lisa|last3=Hildebrandt|first3=Carolin|date=1 December 2012|title=The role of a relative age effect in the first winter Youth Olympic Games in 2012|url=https://bjsm.bmj.com/content/46/15/1038|journal=British Journal of Sports Medicine|language=en|volume=46|issue=15|pages=1038–1043|doi=10.1136/bjsports-2012-091535|issn=0306-3674|pmid=22976907|s2cid=37476293|url-access=subscription}} as well as non-physical sports like shooting.{{Cite journal|last1=Delorme|first1=Nicolas|last2=Raspaud|first2=Michel|date=1 August 2009|title=Is there an influence of relative age on participation in non-physical sports activities? The example of shooting sports|url=https://doi.org/10.1080/02640410902926438|journal=Journal of Sports Sciences|volume=27|issue=10|pages=1035–1042|doi=10.1080/02640410902926438|issn=0264-0414|pmid=19847687|s2cid=1624812}}

Malcolm Gladwell's book Outliers: The Story of Success and the book SuperFreakonomics by Steven Levitt and Stephen Dubner, popularised the issue in respect of Canadian ice-hockey players, European football players, and US Major League baseball players.{{citation needed|date=May 2023}}

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Relative age effects are caused by birthdate eligibility rules but can be affected by parents, coaches and athletes through other mechanisms.{{Cite journal|last1=Thompson|first1=Angus H.|last2=Barnsley|first2=Roger H.|last3=Stebelsky|first3=George|date=1991-06-01|title="Born to Play Ball" The Relative Age Effect and Major League Baseball|url=https://journals.humankinetics.com/view/journals/ssj/8/2/article-p146.xml|journal=Sociology of Sport Journal|language=en-US|volume=8|issue=2|pages=146–151|doi=10.1123/ssj.8.2.146|issn=0741-1235|url-access=subscription}} The Pygmalion effect, Galatea effect, and Matthew effect are examples of effects which impact player motivation.{{Cite journal|last=Harter|first=Susan|date=1978|title=Effectance Motivation Reconsidered. Toward a Developmental Model|url=https://www.karger.com/Article/FullText/271574|journal=Human Development|language=english|volume=21|issue=1|pages=34–64|doi=10.1159/000271574|issn=0018-716X|url-access=subscription}}

In addition to these social factors contextual differences change the distribution with decreased effects in female sports,{{Cite journal|last1=Abel|first1=Ernest L.|last2=Kruger|first2=Michael M.|last3=Pandya|first3=Kalyani|date=August 2011|title=A relative age effect in men's but not women's professional baseball: 1943-1954|url=https://pubmed.ncbi.nlm.nih.gov/22049668/|journal=Psychological Reports|volume=109|issue=1|pages=285–288|doi=10.2466/05.PR0.109.4.285-288|issn=0033-2941|pmid=22049668|s2cid=23937679}}{{Cite journal|last1=Romann|first1=Michael|last2=Fuchslocher|first2=Jörg|date=2014-06-01|title=The Need to Consider Relative Age Effects in Women's Talent Development Process|url=https://doi.org/10.2466/30.10.PMS.118k24w8|journal=Perceptual and Motor Skills|language=en|volume=118|issue=3|pages=651–662|doi=10.2466/30.10.PMS.118k24w8|pmid=25068738|s2cid=207391641|issn=0031-5125|url-access=subscription}} unpopular sports,{{Cite journal|last=Wattie|first=Nick|title=A historical examination of relative age effects in Canadian hockey players.|url=https://scholar.google.com/scholar?q=A%20historical%20examination%20of%20relative%20age%20effects%20in%20Canadian%20hockey%20players|journal=International Journal of Sport Psychology}} at different ages,{{Cite journal|last1=Delorme|first1=N.|last2=Chalabaev|first2=A.|last3=Raspaud|first3=M.|date=2011|title=Relative age is associated with sport dropout: evidence from youth categories of French basketball: Relative age effect and dropout|url=https://onlinelibrary.wiley.com/doi/10.1111/j.1600-0838.2009.01060.x|journal=Scandinavian Journal of Medicine & Science in Sports|language=en|volume=21|issue=1|pages=120–128|doi=10.1111/j.1600-0838.2009.01060.x|pmid=20136758|s2cid=20611526}} individual sports,{{Cite journal|last1=Baker|first1=Joseph|last2=Janning|first2=Christina|last3=Wong|first3=Harmonie|last4=Cobley|first4=Stephen|last5=Schorer|first5=Jörg|date=2014|title=Variations in relative age effects in individual sports: skiing, figure skating and gymnastics|url=https://pubmed.ncbi.nlm.nih.gov/24444205/|journal=European Journal of Sport Science|volume=14|issue=Suppl 1 |pages=S183–190|doi=10.1080/17461391.2012.671369|issn=1536-7290|pmid=24444205|s2cid=205918608}} or sports with a lower reliance on body size,{{Cite journal|last1=Gil|first1=Susana M.|last2=Bidaurrazaga-Letona|first2=Iraia|last3=Larruskain|first3=Jon|last4=Esain|first4=Izaro|last5=Irazusta|first5=Jon|date=2021|title=The relative age effect in young athletes: A countywide analysis of 9-14-year-old participants in all competitive sports|journal=PLOS ONE|volume=16|issue=7|pages=e0254687|doi=10.1371/journal.pone.0254687|issn=1932-6203|pmc=8284647|pmid=34270609|bibcode=2021PLoSO..1654687G|doi-access=free}} with an expected increased effect in male sports, popular sports, or competitive sports. The sports popularity in a geographical or cultural area will affect the relative age distribution relative, with examples seen in volleyball{{Cite journal|last1=Musch|first1=Jochen|last2=Grondin|first2=Simon|date=2001|title=Unequal Competition as an Impediment to Personal Development: A Review of the Relative Age Effect in Sport|url=https://www.sciencedirect.com/science/article/abs/pii/S0273229700905161|journal=Developmental Review|volume=21|issue=2|pages=147–167|doi=10.1006/drev.2000.0516|issn=0273-2297}} and American football.{{Cite journal|last1=Stanaway|first1=Kimberly B.|last2=Hines|first2=Terence M.|date=1995-12-01|title=Lack of a Season of Birth Effect among American Athletes|url=https://doi.org/10.2466/pms.1995.81.3.952|journal=Perceptual and Motor Skills|language=en|volume=81|issue=3|pages=952–954|doi=10.2466/pms.1995.81.3.952|s2cid=144431104|issn=0031-5125|url-access=subscription}}

The early maturation levels giving physical advantages to first quarter individuals can create the bias, seen in players' height in basketball,{{Cite journal|last1=Delorme|first1=N.|last2=Raspaud|first2=M.|date=2009|title=The relative age effect in young French basketball players: a study on the whole population|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0838.2008.00781.x|journal=Scandinavian Journal of Medicine & Science in Sports|language=en|volume=19|issue=2|pages=235–242|doi=10.1111/j.1600-0838.2008.00781.x|pmid=18298612|s2cid=126598|issn=1600-0838}} dominant hand in tennis,{{Cite journal|last1=Loffing|first1=Florian|last2=Schorer|first2=Jörg|last3=Cobley|first3=Steve P.|date=2010-06-01|title=Relative Age Effects are a developmental problem in tennis: but not necessarily when you're left-handed!|url=https://doi.org/10.1080/13598139.2010.488084|journal=High Ability Studies|volume=21|issue=1|pages=19–25|doi=10.1080/13598139.2010.488084|s2cid=145150287|issn=1359-8139|url-access=subscription}} or size in a cricket position,{{Cite journal|last1=Côté|first1=Jean|last2=Macdonald|first2=Dany J.|last3=Baker|first3=Joseph|last4=Abernethy|first4=Bruce|date=2006|title=When "where" is more important than "when": birthplace and birthdate effects on the achievement of sporting expertise|url=https://pubmed.ncbi.nlm.nih.gov/17115521/|journal=Journal of Sports Sciences|volume=24|issue=10|pages=1065–1073|doi=10.1080/02640410500432490|issn=0264-0414|pmid=17115521|hdl=1974/14413|s2cid=12638438|hdl-access=free}} but physical size isn't always the cause.{{Cite journal|last1=Sherar|first1=Lauren B.|last2=Baxter-Jones|first2=Adam D. G.|last3=Faulkner|first3=Robert A.|last4=Russell|first4=Keith W.|date=2007|title=Do physical maturity and birth date predict talent in male youth ice hockey players?|url=https://pubmed.ncbi.nlm.nih.gov/17474041/|journal=Journal of Sports Sciences|volume=25|issue=8|pages=879–886|doi=10.1080/02640410600908001|issn=0264-0414|pmid=17474041|s2cid=24530414}} Older individuals also gain more competence{{Citation|last=Harter|first=Susan|title=Causes and Consequences of Low Self-Esteem in Children and Adolescents|date=1993|url=https://doi.org/10.1007/978-1-4684-8956-9_5|work=Self-Esteem: The Puzzle of Low Self-Regard|pages=87–116|editor-last=Baumeister|editor-first=Roy F.|series=The Plenum Series in Social / Clinical Psychology|place=Boston, MA|publisher=Springer US|language=en|doi=10.1007/978-1-4684-8956-9_5|isbn=978-1-4684-8956-9|access-date=2021-11-12|url-access=subscription}} and self-efficacy,{{Cite journal|last=Heffernan|first=Colleen J.|date=1988|title=Social foundations of thought and action: A social cognitive theory, Albert Bandura Englewood Cliffs, New Jersey: Prentice Hall, 1986, xiii + 617 pp. Hardback. US$39.50.|url=https://www.cambridge.org/core/journals/behaviour-change/article/abs/social-foundations-of-thought-and-action-a-social-cognitive-theory-banduraalbertenglewood-cliffs-new-jersey-prentice-hall-1986-xiii-617-pp-hardback-us3950/B601D38456EF1C78547064C6D8C07C2C|journal=Behaviour Change|language=en|volume=5|issue=1|pages=37–38|doi=10.1017/S0813483900008238|issn=0813-4839|url-access=subscription}} increasing the performance gap. These advantages lead to increased dropout rates for Q1 births.{{Cite journal|last1=García|first1=Miguel Saavedra|last2=Aguilar|first2=Óscar Gutiérrez|last3=Romero|first3=Juan J Fernández|last4=Lastra|first4=David Fernández|last5=Oliveira|first5=Gabriel Eiras|date=2014-10-01|title=Relative age effect in lower categories of international basketball|url=https://doi.org/10.1177/1012690212462832|journal=International Review for the Sociology of Sport|language=en|volume=49|issue=5|pages=526–535|doi=10.1177/1012690212462832|s2cid=145132099|issn=1012-6902|url-access=subscription}}{{Cite journal|last1=Delorme|first1=Nicolas|last2=Boiché|first2=Julie|last3=Raspaud|first3=Michel|date=1 May 2010|title=Relative age and dropout in French male soccer|url=https://doi.org/10.1080/02640411003663276|journal=Journal of Sports Sciences|volume=28|issue=7|pages=717–722|doi=10.1080/02640411003663276|issn=0264-0414|pmid=20480428|s2cid=6176116}} However, the bias for sports where height and mass impedes flexibility, rotational speed and the strength to mass ratio, maturational delay may be preferred as seen in gymnastics.{{Cite journal|last=Baxter-Jones|first=Adam D.G.|date=1995|title=Growth and Development of Young Athletes: Should Competition Levels be Age Related?|url=http://link.springer.com/10.2165/00007256-199520020-00001|journal=Sports Medicine|language=en|volume=20|issue=2|pages=59–64|doi=10.2165/00007256-199520020-00001|pmid=7481282|s2cid=45304762|issn=0112-1642|url-access=subscription}}

With an adult group the relative age has the opposite meaning,{{Cite journal|last1=Medic|first1=Nikola|last2=Starkes|first2=Janet L.|last3=Young|first3=Bradley W.|date=2007|title=Examining relative age effects on performance achievement and participation rates in Masters athletes|url=https://pubmed.ncbi.nlm.nih.gov/17786690/|journal=Journal of Sports Sciences|volume=25|issue=12|pages=1377–1384|doi=10.1080/02640410601110128|issn=0264-0414|pmid=17786690|s2cid=6530220}} as performance declines in age,{{Cite journal|last1=Baker|first1=Joseph|last2=Deakin|first2=Janice|last3=Horton|first3=Sean|last4=Pearce|first4=G. William|date=2007|title=Maintenance of skilled performance with age: a descriptive examination of professional golfers|url=https://pubmed.ncbi.nlm.nih.gov/17724396/|journal=Journal of Aging and Physical Activity|volume=15|issue=3|pages=300–317|doi=10.1123/japa.15.3.300|issn=1063-8652|pmid=17724396}} and is more significant with more physically demanding sports,{{Cite journal|last1=Bortz|first1=W. M.|date=1996|title=How fast do we age? Exercise performance over time as a biomarker|journal=The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences|volume=51|issue=5|pages=M223–225|doi=10.1093/gerona/51a.5.m223|issn=1079-5006|pmid=8808993|doi-access=free}} depending on what age the average peak performance level is, in that sport.{{Cite journal|last=Starkes|first=Janet|title=Aging and the retention of sport expertise.|url=https://scholar.google.com/scholar?q=Aging%20and%20the%20retention%20of%20sport%20expertise.|journal=International Journal of Sport Psychology}} The "underdog effect" has shown that those late birth individuals may see better chances{{Cite journal|last1=Schorer|first1=J.|last2=Cobley|first2=S.|last3=Büsch|first3=D.|last4=Bräutigam|first4=H.|last5=Baker|first5=J.|date=2009|title=Influences of competition level, gender, player nationality, career stage and playing position on relative age effects|journal=Scandinavian Journal of Medicine & Science in Sports|language=en|volume=19|issue=5|pages=720–730|doi=10.1111/j.1600-0838.2008.00838.x|pmid=18627551|s2cid=1084598|issn=1600-0838|doi-access=free}} if they are selected to play, with the advantage decreasing after selection.{{Cite journal|last1=Vaeyens|first1=Roel|last2=Philippaerts|first2=Renaat M.|last3=Malina|first3=Robert M.|date=2005|title=The relative age effect in soccer: a match-related perspective|url=https://pubmed.ncbi.nlm.nih.gov/16195025/|journal=Journal of Sports Sciences|volume=23|issue=7|pages=747–756|doi=10.1080/02640410400022052|issn=0264-0414|pmid=16195025|s2cid=19513513}}

Playing position, federation membership, and individual and team performance also contribute to the effect, with older players having a higher risk of injury.{{Cite journal|last1=Wattie|first1=Nick|last2=Cobley|first2=Stephen|last3=Macpherson|first3=Alison|last4=Howard|first4=Andrew|last5=Montelpare|first5=William J.|last6=Baker|first6=Joseph|date=2007|title=Injuries in Canadian youth ice hockey: the influence of relative age|url=https://pubmed.ncbi.nlm.nih.gov/17606571/|journal=Pediatrics|volume=120|issue=1|pages=142–148|doi=10.1542/peds.2006-2672|issn=1098-4275|pmid=17606571|s2cid=24189760}}

Various methods have been suggested and tested to reduce the relative age effect like moving the cut off dates, expanding the age group range,{{Cite journal|last=Boucher|first=J|title=The novem system: A practical solution to age grouping.|url=https://www.cabdirect.org/cabdirect/abstract/19911888758|journal=Cahper Journal}} birthdate quotas for the players,{{Cite journal|title=APA PsycNet|url=https://doi.apa.org/doiLanding?doi=10.1037/h0079927|access-date=2021-11-12|journal=Canadian Journal of Behavioural Science |year = 1988|volume = 20|issue = 2|pages = 167–176|doi=10.1037/h0079927|last1 = Barnsley|first1 = Roger H.|last2 = Thompson|first2 = A. H.|url-access = subscription}} the average team age (ATA) method for eligibility,{{Cite book|last1=Verbeek|first1=J.|last2=Lawrence|first2=S.|last3=van der Breggen|first3=J.|last4=Kelly|first4=A.|last5=Jonker|first5=L.|title=Birth Advantages and Relative Age Effects in Sport |chapter=The average team age method and its potential to reduce relative age effects.|url=https://www.taylorfrancis.com/chapters/edit/10.4324/9781003163572-10/average-team-age-method-potential-reduce-relative-age-effects-jan-verbeek-steve-lawrence-jorg-van-der-breggen-adam-kelly-laura-jonker|publisher=Routledge|year=2021 |pages=107–124 |doi=10.4324/9781003163572-10 |isbn=9781003163572 |s2cid=234878601 }}{{Cite journal|last1=Helsen|first1=Werner F.|last2=Starkes|first2=Janet L.|last3=Van Winckel|first3=Jan|date=1998|title=The influence of relative age on success and dropout in male soccer players|url=https://pubmed.ncbi.nlm.nih.gov/28561412/|journal=American Journal of Human Biology|volume=10|issue=6|pages=791–798|doi=10.1002/(SICI)1520-6300(1998)10:6<791::AID-AJHB10>3.0.CO;2-1|issn=1520-6300|pmid=28561412|s2cid=32958835 }} or grouping by height and weight. Some methods have struggled to find success due to the effect moving with selection dates. Making the relative age known to the individuals in the environment have shown less bias in talent identification reducing the relative age effect.{{Cite journal|last=Mann|first=David|title=Age-ordered shirt numbering reduces the selection bias associated with the relative age effect|journal=Journal of Sports Sciences|year=2017|volume=35|issue=8|pages=784–790|doi=10.1080/02640414.2016.1189588|pmid=27238077|s2cid=30301449|doi-access=free|hdl=1871.1/8699ca89-7bc5-4be7-b61a-bf8841dc3106|hdl-access=free}}

Birthday banding,{{Cite journal|last1=Kelly|first1=Adam L.|last2=Jackson|first2=Daniel T.|last3=Taylor|first3=Josh J.|last4=Jeffreys|first4=Mark A.|last5=Turnnidge|first5=Jennifer|date=2020|title="Birthday-Banding" as a Strategy to Moderate the Relative Age Effect: A Case Study Into the England Squash Talent Pathway|journal=Frontiers in Sports and Active Living|volume=2|pages=573890|doi=10.3389/fspor.2020.573890|issn=2624-9367|pmc=7739587|pmid=33345136|doi-access=free}} and re-calculating scores based on relative age,{{cite journal|last1=Romann|first1=M|last2=Cobley|first2=S|year=2015|title=Relative Age Effects in Athletic Sprinting and Corrective Adjustments as a Solution for Their Removal|journal=PLOS ONE|volume=10|issue=4|pages=e0122988|bibcode=2015PLoSO..1022988R|doi=10.1371/journal.pone.0122988|pmc=4386815|pmid=25844642|doi-access=free}} are other methods used to reduce the effects,{{cite journal|last1=Reeves|first1=M|last2=Enright|first2=K|last3=Dowling|first3=J|last4=Roberts|first4=S|date=2018|title=Stakeholders' understanding and perceptions of bio-banding in junior-elite football training|url=http://clok.uclan.ac.uk/25214/1/25214%20Paper%25207%2520-%2520FINAL.pdf|journal=Soccer & Society|volume=19|pages=1166–1182|doi=10.1080/14660970.2018.1432384|s2cid=148894870}} with bio-banding seeing the most research, showing benefit to early and late maturing players,{{Cite journal|last1=Hill|first1=Megan|last2=Spencer|first2=Amy|last3=McGee|first3=Darragh|last4=Scott|first4=Sam|last5=Frame|first5=Malcolm|last6=Cumming|first6=Sean P.|date=2020-05-18|title=The psychology of bio-banding: a Vygotskian perspective|url=https://doi.org/10.1080/03014460.2020.1797163|journal=Annals of Human Biology|volume=47|issue=4|pages=328–335|doi=10.1080/03014460.2020.1797163|issn=0301-4460|pmid=32674664|s2cid=220607644}} both in academy football{{Cite journal|last1=Bradley|first1=Ben|last2=Johnson|first2=David|last3=Hill|first3=Megan|last4=McGee|first4=Darragh|last5=Kana-Ah|first5=Adam|last6=Sharpin|first6=Callum|last7=Sharp|first7=Peter|last8=Kelly|first8=Adam|last9=Cumming|first9=Sean P.|last10=Malina|first10=Robert M.|date=2019|title=Bio-banding in academy football: player's perceptions of a maturity matched tournament|url=https://pubmed.ncbi.nlm.nih.gov/31288575/|journal=Annals of Human Biology|volume=46|issue=5|pages=400–408|doi=10.1080/03014460.2019.1640284|issn=1464-5033|pmid=31288575|s2cid=195871072}} and in recreational football.{{Cite journal|last1=Romann|first1=Michael|last2=Lüdin|first2=Dennis|last3=Born|first3=Dennis-Peter|date=2020-05-12|title=Bio-banding in junior soccer players: a pilot study|journal=BMC Research Notes|volume=13|issue=1|pages=240|doi=10.1186/s13104-020-05083-5|issn=1756-0500|pmc=7216411|pmid=32398110 |doi-access=free }} Bio-banding can help promote appropriate training loads and reduce injury risk,{{Cite journal|last1=Malina|first1=Robert M.|last2=Cumming|first2=Sean P.|last3=Rogol|first3=Alan D.|last4=Coelho-E-Silva|first4=Manuel J.|last5=Figueiredo|first5=Antonio J.|last6=Konarski|first6=Jan M.|last7=Kozieł|first7=Sławomir M.|date=2019|title=Bio-Banding in Youth Sports: Background, Concept, and Application|url=https://pubmed.ncbi.nlm.nih.gov/31429034/|journal=Sports Medicine|volume=49|issue=11|pages=1671–1685|doi=10.1007/s40279-019-01166-x|issn=1179-2035|pmid=31429034|s2cid=201058305}} while increasing technical demands from players,{{Cite journal|last1=Abbott|first1=Will|last2=Williams|first2=Stuart|last3=Brickley|first3=Gary|last4=Smeeton|first4=Nicholas J.|date=2019-08-14|title=Effects of Bio-Banding upon Physical and Technical Performance during Soccer Competition: A Preliminary Analysis|journal=Sports |volume=7|issue=8|pages=E193|doi=10.3390/sports7080193|issn=2075-4663|pmc=6722793|pmid=31416230|doi-access=free}} however, sports already categorized by maturation metrics like Judo,{{Cite journal|last1=Giudicelli|first1=Bruno B.|last2=Luz|first2=Leonardo G. O.|last3=Sogut|first3=Mustafa|last4=Massart|first4=Alain G.|last5=Júnior|first5=Arnaldo C.|last6=Figueiredo|first6=António J.|date=2020-01-05|title=Bio-Banding in Judo: The Mediation Role of Anthropometric Variables on the Maturation Effect|journal=International Journal of Environmental Research and Public Health|volume=17|issue=1|pages=E361|doi=10.3390/ijerph17010361|issn=1660-4601|pmc=6981667|pmid=31948074|doi-access=free}} may not see those effects. More longitudinal studies are needed,{{Cite journal|last1=Stănilă|first1=Alexandra Mihaela|last2=Lupşa|first2=Marius Matichescu|last3=Stănilă|first3=Cătălin|date=2020-09-01|title=BIO-BANDING from concept to practice in sports|journal=Timisoara Physical Education and Rehabilitation Journal|language=en|volume=13|issue=24|pages=19–24|doi=10.2478/tperj-2020-0003|s2cid=220772237|doi-access=free}} alongside more reliable ways to band individuals,{{Cite journal|last1=Reeves|first1=Matthew J.|last2=Enright|first2=Kevin J.|last3=Dowling|first3=Jack|last4=Roberts|first4=Simon J.|date=2018-11-17|title=Stakeholders' understanding and perceptions of bio-banding in junior-elite football training|url=https://doi.org/10.1080/14660970.2018.1432384|journal=Soccer & Society|volume=19|issue=8|pages=1166–1182|doi=10.1080/14660970.2018.1432384|s2cid=148894870|issn=1466-0970}} as biological, psychological and social development doesn't progress in synchrony,{{Cite journal|last1=Cumming|first1=Sean P.|last2=Lloyd|first2=Rhodri S.|last3=Oliver|first3=Jon L.|last4=Eisenmann|first4=Joey C.|last5=Malina|first5=Robert M.|date=2017|title=Bio-banding in Sport: Applications to Competition, Talent Identification, and Strength and Conditioning of Youth Athletes|url=https://journals.lww.com/nsca-scj/Fulltext/2017/04000/Bio_banding_in_Sport__Applications_to_Competition,.6.aspx|journal=Strength & Conditioning Journal|language=en-US|volume=39|issue=2|pages=34–47|doi=10.1519/SSC.0000000000000281|hdl=10369/8460|issn=1524-1602|url-access=subscription}} creating different imbalances in the groups.{{citation needed|date=August 2024}}

File:Oxford 10 years.png

The Academic year is decided by education authorities with August or September being common cut-off dates in the Northern Hemisphere and February or March cut-off dates in the Southern Hemisphere.

The third graph illustrates the relative age effect in graduations from the University of Oxford over a 10-year period, which has also been seen in UK Nobel laureates.{{Cite journal|last1=Fukunaga|first1=Hisanori|last2=Taguri|first2=Masataka|last3=Morita|first3=Satoshi|date=2013-10-01|title=Relative age effect on Nobel laureates in the UK|url=https://doi.org/10.1177/2042533313492514|journal=JRSM Short Reports|language=en|volume=4|issue=10|pages=2042533313492514|doi=10.1177/2042533313492514|issn=2042-5333|pmc=3831864|pmid=24319580}}

The relative age effect and reversal effect are evident in education,{{cite journal|last1=Jeronimus|first1=Bertus F|last2=Stavrakakis|first2=Nikolaos|last3=Veenstra|first3=René|last4=Oldehinkel|first4=Albertine J|year=2015|title=Relative Age Effects in Dutch Adolescents: Concurrent and Prospective Analyses|journal=PLOS ONE|volume=10|issue=6|pages=e0128856|doi=10.1371/journal.pone.0128856|pmc=4468064|pmid=26076384|bibcode=2015PLoSO..1028856J|doi-access=free}} with older students on average scoring higher marks, getting into more gifted and talented programs,{{Cite journal|title=APA PsycNet|url=https://doi.apa.org/doiLanding?doi=10.1037/a0013845|access-date=2021-11-15|journal=Journal of Educational Psychology|date = May 2009|volume = 101|issue = 2|pages = 520–528|doi=10.1037/a0013845|last1 = Cobley|first1 = Stephen|last2 = McKenna|first2 = Jim|last3 = Baker|first3 = Joeseph|last4 = Wattie|first4 = Nick|url-access = subscription}} and being more likely to attend higher education{{cite journal|last1=Bedard|first1=K|last2=Dhuey|first2=E|author2-link=Elizabeth Dhuey|year=2006|title=The Persistence of Early Childhood Maturity: International Evidence of Long-Run Age Effects|journal=The Quarterly Journal of Economics|volume=121|issue=4|pages=1437–72|doi=10.1093/qje/121.4.1437|jstor=25098831}} in academic schools over vocational schools,{{cite journal|last1=Ponzo|first1=Michela|last2=Scoppa|first2=Vincenzo|year=2014|title=The long-lasting effects of school entry age: Evidence from Italian students|journal=Journal of Policy Modeling|volume=36|issue=3|pages=578–99|doi=10.1016/j.jpolmod.2014.04.001}} not necessarily due to higher intelligence.{{Cite journal|last=Shearer|first=E.|date=1967-12-01|title=The Effect of Date of Birth on Teachers' Assessments of Children|url=https://doi.org/10.1080/0013188670100104|journal=Educational Research|volume=10|issue=1|pages=51–56|doi=10.1080/0013188670100104|issn=0013-1881|url-access=subscription}} The Matthew effect again plays a role, as the skills learned early in education compound over time, increasing the advantage,{{Citation|last1=Cunha|first1=Flavio|title=Chapter 12 Interpreting the Evidence on Life Cycle Skill Formation|date=2006-01-01|url=https://www.sciencedirect.com/science/article/pii/S1574069206010129|volume=1|pages=697–812|editor-last=Hanushek|editor-first=E.|publisher=Elsevier|language=en|access-date=2021-11-13|last2=Heckman|first2=James J.|last3=Lochner|first3=Lance|last4=Masterov|first4=Dimitriy V.|series=Handbook of the Economics of Education|doi=10.1016/S1574-0692(06)01012-9|isbn=9780444513991|editor2-last=Welch|editor2-first=F.}} with older students becoming more likely to take up leadership roles. However, like in sport, the effect diminishes over time after middle school,{{Cite journal|last1=Hauck|first1=Anne Logan|last2=Finch|first2=A. J.|date=1993|title=The effect of relative age on achievement in middle school|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/1520-6807%28199301%2930%3A1%3C74%3A%3AAID-PITS2310300112%3E3.0.CO%3B2-E|journal=Psychology in the Schools|language=en|volume=30|issue=1|pages=74–79|doi=10.1002/1520-6807(199301)30:1<74::AID-PITS2310300112>3.0.CO;2-E|issn=1520-6807|url-access=subscription}} and those born later in the year perform better in university education.{{Cite journal|last1=Russell|first1=R. J. H.|last2=Startup|first2=M. J.|date=1986-01-01|title=Month of birth and academic achievement|url=https://dx.doi.org/10.1016/0191-8869%2886%2990082-6|journal=Personality and Individual Differences|language=en|volume=7|issue=6|pages=839–846|doi=10.1016/0191-8869(86)90082-6|issn=0191-8869|url-access=subscription}}

A relative age effect has also been observed in the context of leadership. An over-representation starts in high-school leadership activities such as sports team captain or club president.{{cite journal |doi=10.1016/j.econedurev.2006.08.005 |title=What makes a leader? Relative age and high school leadership |journal=Economics of Education Review |volume=27 |issue=2 |pages=173–83 |year=2008 |last1=Dhuey |first1=Elizabeth |last2=Lipscomb |first2=Stephen |citeseerx=10.1.1.394.8881 }} Then in adult life, this over-representation has been observed in top managerial positions (CEOs of S&P 500 companies),{{cite journal |doi=10.1016/j.econlet.2012.08.017 |title=The relative-age effect and career success: Evidence from corporate CEOs |journal=Economics Letters |volume=117 |issue=3 |pages=660–2 |year=2012 |last1=Du |first1=Qianqian |last2=Gao |first2=Huasheng |last3=Levi |first3=Maurice D }} and in top political positions, both in the USA (senators and representatives),{{cite journal |doi=10.1111/rssa.12154 |title=Born leaders: Political selection and the relative age effect in the US Congress |journal= Journal of the Royal Statistical Society, Series A (Statistics in Society)|volume=179 |issue=3 |pages=809–29 |year=2016 |last1=Muller |first1=Daniel |last2=Page |first2=Lionel |s2cid=124379974 |url=http://purl.org/au-research/grants/arc/DE120101270 |doi-access=free }} and in Finland (MPs).{{cite web|url=http://www.doria.fi/bitstream/handle/10024/148931/wp94.pdf?sequence=1|format=PDF|title=Gender Specific Relative Age Effects in Politics and Football|website=Doria.fi|access-date=8 November 2021}}

Seasonal birth in humans varies, and alongside the relative age effect the epidemiology of seasonal births show over-representations in health conditions like ADHD{{cite journal|last1=Morrow|first1=R. L|last2=Garland|first2=E. J|last3=Wright|first3=J. M|last4=MacLure|first4=M|last5=Taylor|first5=S|last6=Dormuth|first6=C. R|year=2012|title=Influence of relative age on diagnosis and treatment of attention-deficit/hyperactivity disorder in children|journal=Canadian Medical Association Journal|volume=184|issue=7|pages=755–62|doi=10.1503/cmaj.111619|pmc=3328520|pmid=22392937}} and schizophrenia,{{cite journal|last1=Davies|first1=G|last2=Welham|first2=J|last3=Chant|first3=D|last4=Torrey|first4=E. F|last5=McGrath|first5=J|year=2003|title=A Systematic Review and Meta-analysis of Northern Hemisphere Season of Birth Studies in Schizophrenia|journal=Schizophrenia Bulletin|volume=29|issue=3|pages=587–93|doi=10.1093/oxfordjournals.schbul.a007030|pmid=14609251|doi-access=free}}{{cite web|title=Season of Birth of Students Receiving Special Education Services Under a Diagnosis of Emotional and Behavioral Disorder|url=http://www.eduratio.be/raepolizzi.pdf|access-date=8 November 2021|website=Eduratio.be}} with one study finding "that higher school starting age lowers the propensity to commit crime at young ages."{{cite journal|last1=Landersø|first1=Rasmus|last2=Nielsen|first2=Helena Skyt|last3=Simonsen|first3=Marianne|year=2017|title=School Starting Age and the Crime-age Profile|url=https://www.econstor.eu/bitstream/10419/114153/1/dp9279.pdf|journal=The Economic Journal|volume=127|issue=602|pages=1096–118|doi=10.1111/ecoj.12325|ssrn=2984362|s2cid=155576753}} However, other studies failed to replicate relative age effects on temperament, mood, or physical development.

Obesity has been linked to season of birth with increased chances,{{Cite journal|last1=Hillman|first1=R. W.|last2=Conway|first2=H. C.|date=1972|title=Season of birth and relative body weight|journal=The American Journal of Clinical Nutrition|volume=25|issue=3|pages=279–281|doi=10.1093/ajcn/25.3.279|issn=0002-9165|pmid=5011910|doi-access=free}} potentially due to surrounding temperature at birth,{{Cite journal|last1=Phillips|first1=D. I.|last2=Young|first2=J. B.|date=2000|title=Birth weight, climate at birth and the risk of obesity in adult life|url=https://pubmed.ncbi.nlm.nih.gov/10757620/|journal=International Journal of Obesity and Related Metabolic Disorders|volume=24|issue=3|pages=281–287|doi=10.1038/sj.ijo.0801125|pmid=10757620|s2cid=24898098}} with winter and spring having the highest correlation, but physical inactivity is still a larger risk factor.{{Cite journal|last1=Wattie|first1=Nick|last2=Ardern|first2=Chris I.|last3=Baker|first3=Joseph|date=2008|title=Season of birth and prevalence of overweight and obesity in Canada|url=https://pubmed.ncbi.nlm.nih.gov/18280062/|journal=Early Human Development|volume=84|issue=8|pages=539–547|doi=10.1016/j.earlhumdev.2007.12.010|issn=0378-3782|pmid=18280062}}

Summer babies have increased chances of specific learning difficulties,{{Cite journal|last=Diamond|first=Grace H.|date=1983-03-01|title=The Birthdate Effect: A Maturational Effect?|url=https://doi.org/10.1177/002221948301600306|journal=Journal of Learning Disabilities|language=en|volume=16|issue=3|pages=161–164|doi=10.1177/002221948301600306|pmid=6864105|s2cid=28321784|issn=0022-2194|url-access=subscription}} and winter and spring babies related to schizophrenia and mania/bipolar disorder. Schizoaffective disorder can be related to December–March births, major depression to March–May births, and autism to March births.{{Cite journal|last1=Torrey|first1=E. F.|last2=Miller|first2=J.|last3=Rawlings|first3=R.|last4=Yolken|first4=R. H.|date=1997-11-07|title=Seasonality of births in schizophrenia and bipolar disorder: a review of the literature|journal=Schizophrenia Research|volume=28|issue=1|pages=1–38|doi=10.1016/s0920-9964(97)00092-3|issn=0920-9964|pmid=9428062|s2cid=54259124|doi-access=free}}

Increased rates in seasonal affective disorder relate to the influence of seasonal birth in humans.{{Cite journal|last1=Levitan|first1=Robert D.|last2=Masellis|first2=Mario|last3=Lam|first3=Raymond W.|last4=Kaplan|first4=Allan S.|last5=Davis|first5=Caroline|last6=Tharmalingam|first6=Subi|last7=Mackenzie|first7=Bronwyn|last8=Basile|first8=Vincenzo S.|last9=Kennedy|first9=James L.|date=2006|title=A birth-season/DRD4 gene interaction predicts weight gain and obesity in women with seasonal affective disorder: A seasonal thrifty phenotype hypothesis|journal=Neuropsychopharmacology|volume=31|issue=11|pages=2498–2503|doi=10.1038/sj.npp.1301121|issn=0893-133X|pmid=16760922|s2cid=35504875|doi-access=free}}

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