The relative age effect among elite American youth soccer players.

Glamser, Francis D. ; Vincent, John

Children are frequently grouped by age for school or sport activities in order to control for the effects of intellectual and physical development. However, even when groupings are limited to 1 -year categories, developmental differences can be great (DeMeis & Stearns, 1992). In such cases, some children will be almost a year older than other children. The outcome of this advantage has been termed the relative age effect (RAE) or the birth date effect.

Youth sport programs use cutoff dates to ensure that children will receive age appropriate instruction and to allow for fair competition. However, a large body of research has made it clear that the age differences within a year can have extremely large effects on sports success, especially at elite levels. The discovery of the RAE in children's sports came as the result of an analysis of the birthdays of professional ice hockey players in Canada. Barnsley, Thompson, and Barnsley (1985) found that these players were much more likely to have been born early in the calendar year than in later months. First quarter birthdays were twice as common as last quarter birthdays.

In a follow-up study it was found that the RAE was even greater among elite youth teams (Barnsley & Thompson, 1988). In the case of 9- and 10-year--olds, almost 70% of the top players were born in the first half of the year. More striking was the fact that only 10% had birthdays in the last quarter of the year. Interestingly, the RAE was not evident in professional ice hockey in the 1960s (Daniel & Janssen, 1987). This might suggest that the regimentation and sophistication of youth hockey in recent decades may be a factor in producing the RAE.

Once the RAE in sports was discovered, numerous researchers investigated the effect in various sports around the world. An excellent review of that body of research may be found in the work of Musch and Grondin (2001). Their review presents evidence of a strong RAE in soccer, ice hockey, swimming, and tennis.

The evidence for a strong RAE in international and professional soccer is overwhelming (Musch & Grondin, 2001). Professional players in the United Kingdom, Belgium, Australia, Brazil, France, Netherlands, Germany, and Japan are more likely to have a birthday in the first half of the soccer year than in the second half. The percent of players with birthdays in the first half of the soccer year is near 60 in most studies.

The data for elite youth players in Europe reveal an even stronger RAE (Musch & Grondin, 2001). Studies of players in the United Kingdom, Sweden, and Belgium found approximately 70% of elite youth players had birthdays in the first half of the soccer year. A literature review of the various factors relevant to the early identification of soccer talent by Williams and Reilly (2000) makes it very clear that advanced physical maturation and stature are extremely important in the selection of elite youth soccer players. Children born early in the selection year are greatly advantaged. These authors also note a "residual bias" that accrues from being selected very early in this process. The theoretical underpinnings of the RAE may be found in the concepts of developmental advantage, socialization, and self-fulfilling prophecy. In the initial stages of the selection of young athletes, a 6 to 12 month developmental advantage can be decisive. Slightly older participants tend to possess physical and psychological advantages that make their selection more likely. Once young players are selected for elite sport participation, they are taught the correct skills and techniques, while being socialized into appropriate attitudes for later success by capable coaches. This specialized socialization process is not experienced by players not selected for elite teams. The absence of this early experience puts younger players who were not initially selected at risk of non-selection at subsequent player evaluations. Over time, that disadvantage builds.

Early selection for elite sport participation can become a self-fulfilling prophecy for athletes and coaches. Players begin to think of themselves as talented and are thus likely to invest more time and effort into their sport with predictable results. As the identity of previously selected players becomes known to coaches and administrators, they watch those players more closely lest they miss an elite performer. Thus, players with talent will not be overlooked in subsequent selection processes.

Purpose

This study investigated the relative age effect among a nationwide population of elite male soccer players born in 1984 to see if the pattern found in Europe applies to youth soccer in the United States.

Significance

The significance of this study is underscored by the explosive growth of youth soccer in the United States and the prominent role of the Olympic Development Program (ODP) as the premier talent identification and development program. The ODP is organized by the United States Soccer Federation to identify and train the most talented youth soccer players in the country with the ultimate goal of providing the respective age-segmented and senior national teams with players to represent the United States in FIFA competitions and the Olympic Games. ODP soccer uses January 1--December 31 for its selection year to comply with the fairly recent practice used in international FIFA youth competitions. One criticism of the ODP system is that it has identified and produced quality athletes, in terms of pure speed, power, and strength, but has not produced technically proficient soccer players who can compete with Europe and South America's elite in international competition.

Many of the United States current men's senior national team players were products of the ODP system. In the late 1990's, the United States Soccer Federation declared in "Project 2010" that one of its avowed goals was to have developed sufficient soccer talent to enable the men's national team to compete effectively to win the 2010 World Cup. In 2010, the young men in this study will be in their mid 20's and it is expected that one or two of them will play for the full national team.

Method

Data Collection

Birth dates were acquired from the regional camp rosters of all the 1984 boys ODP regional player pools for the four United States Youth Soccer Federation regions- East, Midwest/North, South, and West. The 147 players whose birth dates were collected were considered to be the most talented players born in 1984, in the United States.

The rationale for analyzing the birth date distribution of elite male youth soccer players born in 1984 was because, in 2001, at the age of 17 nearly all the boys were entering their senior year of high school. This was the point where interest was greatest in college scholarships on the boys' part and in player evaluation by college coaches. This insured maximum participation by all parties at regional camp.

Procedure and Data Analyses

The birth dates of the 147 male regional ODP program players born in 1984 were tabulated by month. These categories were compiled into quarters reflecting the ODP soccer year, which starts on January 1 and ends December 31. Thus, the first quarter included January, February, and March, and the fourth quarter included October, November, and December. The results are presented with basic descriptive statistics such as frequency counts and percentages. Chi-square tests were performed to compare differences between the observed and expected birth rate distributions across the four quarters of the ODP soccer year. The significance level of .05 was selected to determine statistical significance.

Before undertaking an analysis of the birth month of elite soccer players, it is necessary to look at the distribution of all births throughout the year in 1984. Although births are fairly evenly distributed across the year, there are seasonal patterns in the United States. In order, the 3 months with the most births are August, September and July. The 3 months of the fewest births from least to most are February, April, and January. In 1984, 48% of births occurred in the first 6 months of the year, and the first quarter had the fewest total births (U.S. Department of Health and Human Services, 1988). Thus, any RAE favoring early months in the year occurs in spite of fewer births.

Results

Analyses of the birth months of the 147 male ODP regional pool players born in 1984 revealed that the birth months are heavily skewed toward the first half of the year with 102 of 147 boys born in January through June (69%). The Chi-square tests revealed that the difference in the quarterly birth date distribution was significant (p. < 0.001) (see Table 1.). While this percentage is comparable to other studies of elite youth soccer and hockey players in other countries, the distribution is not. The first two quarters have a nearly equal number of players, whereas other studies tend to show a fairly linear downward pattern from the first quarter of the year to the fourth (Barnsley, Thompson, & Legault, 1992).

A more detailed look at the data reveals that the most frequent birth month is January with 26 of the 147 players. Twenty-six (18%) of these elite players have January birthdays compared to the 8% that would be expected by chance. The least common birth month is December, with only 5 of 147 players, or slightly over 3%. In this population of elite youth soccer players, boys born in January are over five times as likely to be selected for the national player pool as are boys born in December.

As noted previously, the pattern of birth months does not follow the linear decline seen in many studies. While January is the highest, all the months through July are fairly high. All the months from August through December are low and comprise less than half the average of the first 7 months (16.29). Being born in the first 7 months of the year appears to be the critical advantage in this population.

There are at least two major differences between soccer in the United States and many other countries that may explain this small disparity with studies in other countries. In most countries, soccer is a highly popular sport that attracts many of the best athletes in that society. A similar situation exists with ice hockey in Canada. This would mean that elite youth teams from which players are selected to play at the national level would be heavily comprised of gifted athletes. Older good athletes would have an advantage over younger ones in the selection process. In the United States, the best athletes tend to be spread among a wide range of sports, especially basketball, football, and baseball, given the high psychic and economic rewards possible. The effect of this on soccer in the United States is to make the outstanding athlete (speed, strength, coordination) less common than in other countries. Thus, slightly younger soccer players of exceptional athletic ability might be more likely to be successful in the selection process than in other countries.

The second difference in U.S. soccer is the use of two different selection years for youth club soccer and ODP soccer. Club soccer uses an August-July selection year while the ODP uses a January-December selection year. This means that the oldest children in club soccer have birthdays that fall in the latter part of the calendar year (August, September, and October), while the oldest children in ODP have birthdays in the first quarter of the calendar year (January, February, and March). Thus, the oldest children in club soccer are among the youngest in ODP. This may reduce the drop out rate for late-year born children, and it may reduce the advantage of children born early in the year. Similarly, data from a study of English elite youth players selected for international competition which uses a January start date as compared to the September date used in England produced a flatter distribution than internal selections (Simmons & Paull, 2001). All of this is conjecture, but the RAE is a powerful phenomenon that has been demonstrated repeatedly in the research literature.

Discussion

The data presented herein support the conclusion that the RAE is as much a major factor in the selection of elite youth male soccer players in the United States as it is in other countries. The reason that the discovery of the RAE in organized sport, which is a fairly recent phenomenon, is a problem is that it implies that talented individuals may have been overlooked because they were born late in the selection year, especially in sports where height, weight, strength, and power are an advantage. The long-term result of the RAE may be a lowering in the overall quality of the highest competitive teams.

There is reason to believe that the RAE was not a factor in the selection of adult elite athletes until about 30 years ago. Grondin and Koren (2000) found no RAE among major league baseball players born before 1940. Daniel and Janssen (1987) found no RAE among National Hockey League players in the sixties and early seventies, and Baumler (1996, as cited in Musch & Grondin, 2001) found no RAE among older German professional soccer players as compared to a strong effect among players under 21. All of this suggests that the structure of youth sports development has changed in Europe and North America over the past 3 decades.

To the extent that the RAE is a product of the organization of the elite youth sport system, some modifications may he in order. One possible reform for elite youth sports would be to use even narrower age ranges to minimize RAE. This theory is given practical credence by one southern state director of coaching, who in the summer of 2001 reported that the male 1988 state ODP team was divided into two teams, with those players born in the first half of the year forming one team, and those players born in the last 6 months of the selection year forming another, because many of the players born in the last 6 months of the selection year were "... too small and/or too slight in physique" to compete successfully against their older cohorts (Boulton, 2001, p. 10).

The results of this study were mirrored across the ODP boys' regional teams, in all the respective age ranges (1985's - 1988's), with an average of 68.5% of the players being born in the first 6 months of the selection year (T. Turner, personal communication, December 3, 2002). Although the results of this study are compelling, they are not conclusive and suggest the need for further empirical study with this population of elite male soccer players to enable stronger inferences to be made.

Table 1

Birth Quarter of Players Born in 1984 By Region

Quarter East Midwest South West Total Quarter

1st Quarter 14 12 17 11 54 (37%)
2nd Quarter 5 10 18 15 48 (33%)
3rd Quarter 8 5 8 6 27 (18%)
4th Quarter 3 7 4 4 18 (12%)
Total 30 34 47 36 147 (100%)

Quarter distribution [chi square]=20.79, df=3, p.<0.001

References

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Barnsley, R. H., Thompson, A. H., & Legault, E (1992). Family planning: football style--The RAE in football. International Review for the Sociology of Sport, 27, 77-88.

Boulton, N. (2001). Mississippi can compete in ODP-if it wants to! Mississippi In Touch, Summer, 10.

Daniel, T. E., & Janssen, C. T. (1987). More on the relative age effect. CAHPER Journal, 53, 21-24.

DeMeis, J., & Stearns, E. (1992). Relationship of school entrance age to academic and social performance. Journal of Educational Research, 86, 21-27.

Grondin, S., & Koren, S. (2000). The relative age effect in professional baseball: A look at the history of mayor league baseball and at current status in Japan. Avante, 6, 64-74.

Musch, J., & Grondin, S. (2001). Unequal competition as an impediment to personal development: A review of the relative age effect in sport. Developmental Review, 21,147-167.

Simmons, C., & Paull, G. (2001). Season-of-birth bias in association football. Journal of Sports Sciences, 19, 677-686.

U.S. Department of Health and Human Services. (1988). Vital statistics of the United States 1984. Washington, D.C.: US Government Printing Office.

Williams, A. M., & Reilly, T. (2000). Talent identification and development in soccer. Journal of Sports Sciences, 18, 657-667.

Address Correspondence To: John Vincent, Ph.D. The University of Alabama College of Education, Department of Kinesiology Box 870312 Tuscaloosa, AL 35487-0312Tel: (205) 348-8369 Fax: (205) 348-0867 E-mail: JVincent@bamaed.ua.edu