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Relative Age Background
Paula Barnsley, while attending a Lethbridge Broncos junior hockey game in the early 1980s, apparently lost interest in the spectacle in front of her and began to read the game program. Paula noticed that most of the players were born in months that fell at the beginning of the calendar year. This began a thirty-five year (so far) collaboration on relative age between Paula's husband, Roger, and myself. Paula, shortly after her discovery, gave up her career as an educational psychologist, and went into law - a puzzling decision. At about the same time, Simon Grondin, a graduate student in Psychology at Laval University, made a similar observation about relative age effects among players in the Quebec Junior Hockey League. We published our findings in English,1 and Simon and his colleagues published theirs in French.2 This being a grand example of the twain not meeting, we did not hear about each other for some years. When we did, we put on a joint symposium on relative age at the 1993 conference of the Canadian Psychological Association.  
     The relative age effect, is strikingly evident in activities that are competitive and where performance is highly correlated with age and maturity. As noted above, the relative age effect in sport was first noted among elite level ice hockey players. These findings demonstrated that for major junior leagues and the National Hockey League, player birth dates decreased in frequency from January through December. It was theorized that this relative age effect arose from the consequences of grouping young boys for entry into organized minor hockey, thereby producing a one-year age range for  the participants. As size, speed, and coordination are highly correlated with age, older players within the age-group will, on average, show superior performance. Thus, it can be said that maturity had been mistaken for ability by coaches, peers and the individuals themselves. The resulting expectations that are created for individual children creates a self-fulfilling prophecy that provides age-advantaged children with greater self-confidence and regard by others. The opposite will likely hold for those younger than their group-mates, with adjustments to poorer initial performance likely including lowered self confidence and self-esteem. One consequence that has been found is an increased drop-out rate for those disadvantaged by age in the past,3 suggesting that given the choice, younger children will seek to leave or avoid an activity in which their competitive position is hampered by their relative age. Predictably, the relative age effect has also been found in other competitive sports such as baseball,4 world class soccer,5 and American football.6 Some of our work has shown that the effects extend to emotional development7 and suicide.8  
     It should be noted that schooling shares many of the structural characteristics of children's sports programs. Children are age grouped for entry into school, are rated according to achievement, and are placed in different programs with different curricula and learning options based on these measures of performance. In line with this logic, a large body of literature has consistently reported a strong effect of the age of school entry on academic achievement. For example, school children with a relative age advantage are more likely to show higher achievement, to be placed in programs for gifted children,9 and to be placed in more challenging educational streams or classes.10,11 Children with a relative age disadvantage, are more likely to be retained ("failed") for an additional year in the same school grade,12 to be referred for psychological assessment,13 and to be placed in a specialized group or provided with a diagnostic label for remedial instruction.14,15 As a consequence of these findings, many have suggested that parents should postpone school entry for those younger children whose birthday places them near the "cutoff" for their age group. The result of such action would place the children in question among the eldest of their eventual classmates, rather than the youngest. This contradicts an earlier tendency of parents to try and arrange early admission for children who were actually too young to make a particular cutoff.16
    Theory. The proposed causal chain from birthdate to differences in achievement, self-regard, and suicide involves the following steps: First, relative age produces differences in achievement that are due to maturation, not ability. Second, these differences lead to variation in self-esteem and confidence. Third, low self-esteem and lack of self confidence are associated with a child's inability to compete with his or her classmates leading, respectively, to depression and hopelessness. Finally, depression and hopelessness, which are generally regarded as the essential ingredients of suicide,17,18 become precursors of self-harming behaviour.
 
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