Selection Bias in the National Hockey League: Relatively Younger Players Outperform Their Draft Slots
Posted: 18 Sep 2012
Date Written: September 18, 2012
Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. To test whether selection bias contributes to RAEs, we analyzed National Hockey League (NHL) drafts from 1980-2006. Compared to those born in the first quarter (i.e., January-March), those born in the fourth quarter were selected 43 draft slots later than their productivity warranted, and they were roughly twice as likely to reach career benchmarks, such as 400 games played or 200 points scored. This selection bias in drafting did not decrease over time, apparently continues to occur, and reduces the playing opportunities of relatively younger players. This bias is remarkable because it is exhibited by professional decision makers evaluating adults in a context where RAEs have been widely publicized. Thus, selection bias based on relative age may be pervasive.
Keywords: relative age, selection processes, talent identification, maturation, ice hockey
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