Relative age effect

"Birthdate effect" redirects here. Not to be confused with Birthday effect.
The distribution of births according to month in the general population

The term relative age effect (RAE), also known as birthdate effect or birth date effect, is used to describe a bias, evident in the upper echelons of youth sport[1] and academia,[2] where participation is higher amongst those born earlier in the relevant selection period (and lower for those born later in the selection period) than would be expected from the distribution of births. The selection period is usually the calendar year, the academic year or the sporting season.[3]

The difference in maturity often contributes to the effect,[4] with age category, skill level and sport context also impacting the risk of the relative age effect. Mid to late adolescent, regional to nation, popular sports seeing the highest risk, and under 11, recreational, unpopular sports seeing the lowest risk.[5]

The terms month of birth bias and season of birth bias are used to describe similar effect but are fundamentally different. Season of birth examines the influence of different prenatal and perinatal seasonal environmental factors like sunlight, temperature, or viral exposure during gestation, that relate to health outcomes.[6] Conversely, the relative age effect shifts with selection dates[7] moving the advantage with the selection period.[8] With influence from social agents,[9] children born soon after the cut-off date are typically included, and a child born soon before the cut-off date excluded.

The distribution, according to month of birth, of players involved in UEFA organised international youth football tournaments in 2010/11
  1. ^ "Birthdate Effects: A Review of the Literature from 1990-on" (PDF). Cambridgeassessment.org.uk. Retrieved 8 November 2021.
  2. ^ Claire Crawford; Lorraine Dearden; Costas Meghir. "When You Are Born Matters: The Impact of Date of Birth on Child Cognitive Outcomes in England" (PDF). Cee.lse.ac.uk. ISSN 2045-6557. Archived from the original (PDF) on 28 January 2012. Retrieved 8 November 2021.
  3. ^ Kelly, Adam L.; Côté, Jean; Jeffreys, Mark; Turnnidge, Jennifer, eds. (2021-06-04). Birth Advantages and Relative Age Effects in Sport: Exploring Organizational Structures and Creating Appropriate Settings. New York: Routledge. doi:10.4324/9781003163572. ISBN 978-1-003-16357-2. S2CID 241069004.
  4. ^ "Long-term relative age effect: Evidence from Italian football". VoxEU.org. 23 April 2016. Retrieved 23 April 2016.
  5. ^ Cite error: The named reference :2 was invoked but never defined (see the help page).
  6. ^ Barry, H.; Bary, H. (1961). "Season of birth. An epidemiological study in psychiatry". Archives of General Psychiatry. 5: 292–300. doi:10.1001/archpsyc.1961.01710150074012. ISSN 0003-990X. PMID 13687345.
  7. ^ Helsen, Werner F.; Starkes, Janet L.; Van Winckel, Jan (2000-11-01). "Effect of a change in selection year on success in male soccer players". American Journal of Human Biology. 12 (6): 729–735. doi:10.1002/1520-6300(200011/12)12:6<729::AID-AJHB2>3.0.CO;2-7. ISSN 1520-6300. PMID 11534065. S2CID 24013421.
  8. ^ Musch, Jochen; Hay, Roy (1999-03-01). "The Relative Age Effect in Soccer: Cross-Cultural Evidence for a Systematic Discrimination against Children Born Late in the Competition Year". Sociology of Sport Journal. 16 (1): 54–64. doi:10.1123/ssj.16.1.54. ISSN 0741-1235.
  9. ^ Hancock, David J.; Adler, Ashley L.; Côté, Jean (2013). "A proposed theoretical model to explain relative age effects in sport". European Journal of Sport Science. 13 (6): 630–637. doi:10.1080/17461391.2013.775352. hdl:1974/14350. ISSN 1536-7290. PMID 24251740. S2CID 32336640.