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Have you ever stopped to wonder the difference a day can make? Say, being born December 31st or January 1st? This small 24-hour window could be the difference between competing in elite vs. recreational sport, or being identified as “gifted”, or (mis)diagnosed with a learning disability in school. Many youth development systems (e.g., sport and education) rely on arbitrary cut-off dates to group individuals into cohorts, which result in age differences among children within a single cohort. Consider that an 11-month age difference among 10-year-old children represents 10% of their total life experience. While this difference may seem trivial, it can lead to a phenomenon known as the relative age effect (RAE). The RAE tends to advantage the oldest individuals in a cohort and disadvantage their relatively younger peers. The implications of RAEs are broad, extending from sport to education to health and wellbeing. For example, the relatively youngest students have been found to achieve lower grades and have poorer school attendance rates (Cobley et al., 2009a), are less likely to attend or complete post-secondary school (Bedard & Dhuey, 2006; Dhuey et al., 2017), demonstrate lower levels of self-esteem (Thompson et al., 2004), and have higher rates of suicide (Thompson et al., 1999) and incarceration for juvenile crimes (Dhuey et al., 2017).

Why does this happen? The answers, it turns out, are fairly straight-forward. Relative age effects tend to occur when individuals are selected based upon their perceived ability and then placed into differing steams (e.g., gifted programs, competitive sport) that offer dissimilar opportunities and resources. The problem is that coaches, teachers, and parents often confuse “talent” with “age.” While they assume they are selecting the most talented children for these elite opportunities, often it is just the oldest among the cohort.

Within sport, we tend to see RAEs most frequently in culturally valued activities such as hockey in Canada, or soccer in England. Unfortunately, RAEs can lead to younger athletes dropping out (e.g., Lemez et al., 2014) thereby missing out on the many positive outcomes associated with sport participation.

Ice hockey has been one of the most frequently studied sports with RAEs occurring as early as age 7 (Hancock et al., 2013), peaking at elite junior levels (≈ 16-21 years), then leveling off somewhat in the NHL (Cobley et al., 2009b). However, there is evidence suggesting that younger athletes who “survive” the system may ultimately become better as a result (Gibbs et al., 2011).

Within sport, RAE is a popular topic among academics and policy makers, having been discussed at previous Sport Canada Research Initiative conferences and featured in the SIRCuit. The RAE has also captured the attention of the popular press, having been profiled in such best-selling books such as Gladwell’s (2008) Outliers: The Story of Success and Levitt and Dubner’s (2009) SuperFreakonomics, sports magazines like Sports Illustrated (Levy, 2011), and on television programs such as 60 Minutes (CBS Interactive, 2012).

The RAE problem that plagues education and sport can lead to inequitable experiences and opportunities for individuals. Researchers must work in collaboration with sport and education stakeholders to develop feasible and attractive solutions to the RAE so that all individuals, regardless of their birthdates, have equal opportunities to experience success in academics and athletics.

About the Author(s)

Laura Chittle is a doctoral candidate in the Department of Kinesiology at the University of Windsor. She is currently funded by a Joseph-Armand Bombardier CGS Doctoral Scholarship and a Sport Canada Research Initiative Grant. Her current dissertation studies are evaluating the role that relative age has on athlete leadership development and positive youth experiences in sport.

Jess C. Dixon is an associate professor of sport management and graduate program coordinator in the Department of Kinesiology at the University of Windsor. His research and scholarly interests are in the areas of strategic management in sport, executive leadership and human resource management in sport, relative age effects in sport, sport finance and economics, and sport management pedagogy. His research has been funded by the Social Sciences and Research Council of Canada (SSHRC) and the Sport Canada Research Initiative (SCRI).

Sean Horton is a professor of lifespan development in the Department of Kinesiology at the University of Windsor. His research interests lie primarily in the area of skill acquisition and expert performance, both in young people and as individuals age. His research is funded by the Social Sciences and Research Council of Canada (SSHRC) and the Ontario Trillium Foundation.

Joe Baker is professor of sport science at York University. He has been examining the factors affecting long-term development and performance of high performance athletes for over two decades. He currently works with several NSOs and PSOs in Canada (e.g., Wheelchair Basketball Canada, Golf Canada, Canadian Paralympic Committee, Canadian Sport Institute Ontario) to improve models of athlete development and the delivery of evidence-based approaches to skill acquisition.


Bedard, K., & Dhuey, E. (2006). The persistence of early childhood maturity: International evidence of long-run age effects. The Quarterly Journal of Economics, 121(4), 1437- 1474.

CBS Interactive (2012). Redshirting: Holding kids back from kindergarten. 60 Minutes. Retrieved from holding-kids- back-from kindergarten/?pageNum=5&tag=contentMain;contentBody

Cobley, S., Baker, J., Wattie, N., & McKenna, J. M. (2009a). How pervasive are relative age effects in secondary school education? Journal of Educational Psychology, 101(2), 520- 528.

Cobley, S., Baker, J., Wattie, N., & McKenna, J. M. (2009b). Annual age-grouping and athlete development: A meta-analytic review of relative age effects in sport. Sports Medicine, 39(3), 235-256.

Dhuey, E., Figlio, D., Karbownik, K., & Roth, J. (2017, August). School starting age and cognitive development [working paper 23660]. Cambridge, MA: National Bureau of Economic Research. Retrieved from

Gibbs, B. G., Jarvis, J. A., & Durfur, M. J. (2011) The rise of the underdog? The relative age effect reversal among Canadian-born NHL hockey players: A reply to Nolan and Howell. International Review for the Sociology of Sport 47(5), 644–649.

Gladwell, M. (2008). Outliers: The story of success. New York, NY: Little, Brown and Company.

Hancock, D. J., Ste-Marie, D. M., & Young, B. W. (2013). Coach selections and the relative age effect in male youth ice hockey. Research Quarterly for Exercise and Sport, 84, 126- 130.

Lemez, S., Baker, J., Horton, S., Wattie, N., & Weir, P. (2014). Examining the relationship between relative age, competition level, and dropout rates in male youth ice-hockey players. Scandinavian Journal of Medicine & Science in Sports, 24(6), 935-942. doi:10.1111/sms.12127

Levitt, S. D., & Dubner, S. J. (2009). SuperFreakonomics. New York, NY: William Morrow.

Levy, J. (2011, August 8). Myth no. 1: The relative-age effect. Sports Illustrated, 115(5), 49.

Thompson, A. H., Barnsley, R. H., Battle, J. (2004). The relative age effect and the development of self-esteem. Educational Research, 46, 313-320.

Thompson, A. H., Barnsley, R. H., & Dyck, R. J. (1999). A new factor in youth suicide: The relative age effect. Canadian Journal of Psychiatry, 44(1), 82-85.

The information presented in SIRC blogs and SIRCuit articles is accurate and reliable as of the date of publication. Developments that occur after the date of publication may impact the current accuracy of the information presented in a previously published blog or article.