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How we calculate age in youth sports can have benefits and consequences
There are several ways to calculate an athlete's age in sport. How this is done is important because of the relative age effect (RAE) and being able to maintain accuracy in historical performance data. Knowing how old someone is carries important meaning in sport and while determining someone's age seems like a no-brainer it's a bit more complicated than many assume.
Not all cultures treat age the same way. In the West we are used to celebrating birthdays on the actual day we were born. Our age officially increases on that day. In some Eastern cultures age changes when the year changes. On 1 January many Chinese, for example, will consider themselves a year older even though their actual birth day may be different.
And, believe it or not, it is still possible that in some developing countries youngsters may not know their birthday or even the year of their birth.
These factors all have to be considered when determining the age of young athletes. But knowing one's actual chronological age is only one kind of age that is important in sport. Other ages can affect training, competition, and the historical records of a sport:
Chronological age - is a person's actual age in years, calculated from the day one is born. For most sports and in most parts of the world this age is treated as the most important and usually is the only one considered when discussing age in sport. However, we now know that considering only an athlete's chronological age is not the best way to encourage participation or retention within sport programs.
Developmental age - is a combination of one's biological maturity coupled with an evaluation of mental, psychological, and emotional development. Determining biological maturity in youth sport is fairly easy (using maturity offset calculations) but mental, psychological, and emotional development is more complicated and, given the resources available in youth sport, is often just a guess. (Note: Bio-banding is an attempt to use developmental age to improve the youth sport experience.)
Relative age - refers to the apparent differences in children who share the same chronological age but various developmental ages. Evidence of these differences exist in any cohort of children. Earlier this year USSA Malaysia published a study which demonstrated the relative age effect for several performance tests in 8-, 9-, 10-, 15-, and 16-year-olds.
Training age - represents the number of years that an athlete has been involved in training. There are two types of training age. The first calculates how long a youngster has been involved in sports overall. Since many training components are similar and transferable between sports, endurance, speed, and agility, for example, it's possible to determine a general training age based on the length of time a child has been involved in sport.
Specific training age refers to the time an athlete has been training in a particular sport and is especially important in skill intensive activities like gymnastics or figure skating.
Chronological age is the one most often used for grouping athletes in sport primarily because it is easy to do and is the most widely accepted. Other methods, though they may provide a more suitable result, are difficult to assess and require a certain knowledge to use effectively. Their lack of widespread use and understanding also make them impractical for large youth sport organizations.
Setting age cutoff dates
Cutoff dates typically used to calculate age for competition usually use either some arbitrary annual date that begins a new sport season or school year, or some other date that may have internal significance to the sport involved.
We have written before that using the first day of a competition as the age determination date helps to mediate the relative age effects permanently present when an arbitrary annual date is used. However, determining age this way merely shifts the relative age effect, it doesn't eliminate it. The main benefit of using the 'day of' method is that the relative age of athletes will change throughout the year, thus no one is perpetually disadvantaged simply due to their birthdate.
This also helps maintain accurate historical performance data; all athletes competing in this system will either be the age they are assumed to be or only a day or so older if they 'age up' on the second or subsequent days of a competition.
Another strategy would be to use narrower age groups for competition. For example, using single year age groups rather than the typical two years can significantly reduce the RAE.
Thinking outside the box: Eliminate age groups!
In sports measured by time, weight, or speed, one possible innovation that can both reduce the RAE and introduce bio-banding elements into a competition is to combine several age groups for competition and then compile results after the fact in single year increments. In this kind of competition athletes can be divided into groups for 12 years and under and then 13 years and over. The wider age spread for competition allows athletes of similar ability to compete together regardless of age and the separation into single year groupings for result purposes helps reduce the RAE.
Coaches can probably see the simplicity and effectiveness of such a competitive/results system but since it could have 9-year-olds competing against 12-year-olds it would be a hard sell to parents of youngsters.
By manipulating age in youth sport it may be possible not only to provide better opportunities for late maturing youngsters but to encourage early maturers to focus on training and skills. Introducing elements of bio-banding and narrowing age groups helps improve development efforts across the board. Rather than simply carry on as we always have, it's worth the effort to look for ways to enhance our youth sport programs.
Bill Price (email@example.com) is the owner and Chief Data Scientist at Sportkid Metrics.