Relative age effect (RAE)

The relative age effect (RAE), also known as the birthdate effect, is a phenomenon associated with youth sports and academics in which children born closer to a specific age cutoff tend to enjoy performance advantages. Birthdate cutoffs determine when children start school and which children are eligible to play youth sports in particular age categories. Research into the relative age effect shows that older children born closer to the age cutoff tend to have more success in academics and athletics than their younger counterparts.

In examining the relative age effect, researchers divide the year as defined by birthdate cutoffs into four quarters. Research consistently shows that children born in the two quarters closest to the cutoff date have quantifiable advantages over children born in the two later quarters. Furthermore, these advantages translate to both academics and athletics. Older children tend to outperform younger peers in the same grade level on standardized tests, while younger student-athletes tend to drop out of sports at higher rates than older children competing in the same age group.

Background

Early studies into the relative age effect were conducted by Thompson Rivers University researchers Roger and Paula Barnsley in the 1980s. Their work was guided by statistical observations showing that younger students within a grade or classroom tended to be diagnosed with learning disabilities at higher rates than older students. Upon closer analysis, the trend could not be explained by factors related to readiness for school, relative maturity, or developmental critical periods that suggest certain cognitive skills are most easily acquired within a specific time window. The phenomenon also appeared to translate to sports, prompting the Barnsleys to partner with fellow psychologist A.H. Thompson to conduct an analysis of the birthdates of successful ice hockey players in multiple high-level leagues.

Revealing their findings in a 1985 paper titled “Hockey Success and Birthdate: The Relative Age Effect,” the researchers found that a far greater proportion of players were born in the early months of the year across three hockey leagues. With January 1 being used as a cutoff date to determine age groupings among players in Canadian youth hockey, the researchers determined that players born closer to that date had a distinct achievement advantage that persisted into adolescence and adulthood. They found that the birthdates of players in the National Hockey League (NHL) were about twice as likely to fall within the first quarter of the year than the final quarter of the year. These trends were even more pronounced among the younger player pools in the major junior Western Hockey League (WHL) and Ontario Hockey League (OHL), with players in these leagues being 3.5 to five times more likely to be born in January than in December.

The researchers also discussed two hypotheses forwarded to explain the data. The first hypothesis suggested that environmental factors, such as fetal nutrition, impact when a child is born and how that child goes on to perform in athletics and academics. The researchers rejected this hypothesis, instead favoring an explanation that ties the relative age effect already observed in academics to athletic achievement.

Overview

Scientists have generated a sizable body of research into the relative age effect since the initial studies carried out by the Barnsleys in the 1980s and early 1990s. This research shows statistically significant, consistent trends that suggest strong correlations between relative age, academic success, and athletic achievement. According to the Barnsleys’ pioneering work, the relative age effect tends to appear when four distinct criteria are all met: (1) birthdates are used to place children in cohort peer groups for a particular academic or athletic activity; (2) the achievements of children within a cohort group are evaluated relative to those of their peers; (3) children are assigned to particular subgroups within the cohort structure based on the results of these evaluations; (4) children in different subgroups participate in different academic or athletic activities relative to their perceived skill or performance level.

In academics, the relative age effect shows that children who are older than their peers in the same grade level tend to enjoy multiple short-term and medium-term performance advantages. For instance, they tend to earn higher scores on standardized tests and develop noncognitive proficiencies more easily. Over the long term, these advantages appear to translate into lower delinquency rates, as children born closer to school enrollment cutoff dates also tend to commit crimes at reduced rates during adolescence and adulthood. Thus, researchers believe that the relative age effect can have lifelong repercussions, with major implications for future productivity, career success, and financial earnings.

In athletics, participants with earlier birthdates tend to benefit from more advanced physical, emotional, and psychological maturity. From a physical standpoint, children born closer to age cutoffs tend to be more developed than their younger peers. These physical development gaps can be significant, considering that age differences can theoretically span up to one full year minus one day. Metrics such as peak height velocity and peak weight velocity, which mark the relative physical maturity of both male and female athletes, both indicate distinct advantages for older participants across a wide range of sports and physical activities. Studies suggest that the relative age effect has a particularly pronounced influence in sports that require higher levels of strength, speed, and endurance.

The emotional and psychological impacts of the relative age effect in youth athletics are more nuanced and difficult to quantify. One hypothesis suggests that younger child athletes may become discouraged more easily because they do not immediately meet with as much success as their older peers or opponents, thus losing their motivation to continue competing and developing.

For young athletes, the relative age effect appears to diminish starting around age 17, after which achievement outcomes among athletes with disparate birthdates begin to even out. However, researchers note that dropout rates from youth athletics programs tend to peak at earlier ages, when participants are still influenced by the relative age effect. Thus, the extent to which gifted athletes quit sports before reaching their full potential remains unknown.

Bibliography

Barnsley, R.H., et al. "Hockey Success and Birthdate: The Relative Age Effect." Journal of the Canadian Association for Health, Physical Education and Recreation, vol. 51, no. 8, 1985, pp. 23-28.

Bezuglov, Eduard, et al. "Is There a Relative Age Effect among the Most Successful Track and Field Athletes?" Journal of Human Kinetics, vol. 92, 2023, p. 193, doi.org/10.5114/jhk/174497. Accessed 17 Dec. 2024.

Ek, Staffan, et al. "Relative Age Effect of Sport Academy Adolescents, a Physiological Evaluation." Sports, vol. 8, no. 1, 2020, p. 5, doi.org/10.3390/sports8010005. Accessed 17 Dec. 2024.

Green, Tom. “Relative Age Effect.” Science for Sport, 9 Feb. 2024, www.scienceforsport.com/relative-age-effect. Accessed 17 Dec. 2024.

Jurbala, Paul. “What’s the Latest on Relative Age Effects?” Sport for Life, sportforlife.ca/whats-the-latest-on-relative-age-effects. Accessed 17 Dec. 2024.

Tenenbaum, Gershon, and Robert C. Eklund. Handbook of Sport Psychology. John Wiley & Sons, 2007, p. 194.

Thomas, Katherine T., et al. Physical Education Methods for Elementary Teachers. Human Kinetics, 2008.

Thoren, Katharina, et al. "Relative Age Effects in Mathematics and Reading: Investigating the Generalizability across Students, Time and Classes." Frontiers in Psychology, vol. 7, 2016, p. 195306, doi.org/10.3389/fpsyg.2016.00679. Accessed 17 Dec. 2024.