Performance rises to a peak in the mid to late twenties for most sports and declines thereafter, at a rate the sport determines.
Aggregate curves are built from players still playing, and the ones who fell away are absent from the later points. Corrections for this move the peak earlier and steepen the decline. Sprinting, endurance and skill-dominant sports peak at different ages, so a single curve describes none of them.
In practice
- A club paying for a thirty-year-old's last three seasons is buying the flattest part of a biased curve.
- A cohort measured only where it survives will show every trait declining more gently than it does.
- Possible explanations
- The explanation is the interaction of physical capacity, which declines from the late twenties, and skill, which accumulates, so the peak falls where the two cross, later in sports where judgement matters most.
- In its favour
- Peaks do differ systematically by sport in the direction the account predicts, and longitudinal data on individual athletes show the rise and decline clearly.
- Against it
- Aggregate curves are biased by survivorship, since players who decline early leave the sample, which flattens the measured decline, and corrections move the peak earlier and steepen the fall.
- Standing
- Estimated peaks are biased by survivorship: players who decline early leave the sample, which flattens the measured decline. Peak ages also differ substantially by sport, position and the demand being measured.
- Subject
- Sport & Performance
- Essay
- The best-measured contests there are