How to best use Age Ordered Numbered Bibs in cricket development.


How Age Ordered Numbered Bibs reduce RAEs in youth football

The ECB recently teased two videos on the coach development platform @icoachcricket covering Relative Age Effects and maturation selection bias. In the RAEs video they showed how Age Ordered Numbered Bibs (AONBs) can be used to add context to trials/training to reduce RAE.

David Court, Men’s Player Identification and Talent Pathway Lead at the ECB, recently confirmed:

 ‘… we have begun some research into the effectiveness of using age ordered bibs in relation to RAE this year. We have 4 counties on board and they are using it throughout their selection process and hope to compare the numbers to their previous years data and in comparison to the rest of the country.’ 

No other details are known other than they are also using a different colour for each birth quarter to add further context. Testing AONBs has never been done in cricket before, as far as I am aware, so some teething problems may be encountered.

AONBs are being used at a number of Premier League football academies but what is best practice? Is it appropriate to use AONBs for all age groups? When does maturation selection bias become a more important factor than RAEs?

It is important to understand the context and timing of how both RAEs and maturation affect selection bias for both girls and boys. Maturation selection bias can start from around age 9 for girls and 11 for boys. The average age for being at the peak of the growth spurt is 12 for girls and 14 for boys but there is large variance between individuals. There are likely reverse maturation effects in girls so that it is late maturers who are over selected but there has been no research on this in cricket yet. Also accumulated RAEs in the boys pathway start to decline from U15, but for girls, currently, there is evidence that RAEs continue to accumulate until junior to senior transition.

Johnson et al (2017) found that, for male Academy football, maturation has 10x more effect on selection bias than RAEs during adolescence. At this year’s (2023) Bunbury festival (boys Regional U15s) it was found that there were twice as many early maturers and no late maturers within the 56 players.

So, for boys, should we be using AONBs in birth date order up until U12 and in biological age order from U13s and above? For girls and any environments unable to measure biological age using the Khamis Roche method, should we be using AONBs in birth date order for all age groups? 

Unanswered questions

Is there utility in using biological age for numbering and four colours for birth quarter?

There may be options for how biological age ordering is done with AONBs. This needs further exploration.

Should AONB biological age ordering for boys from the earliest age groups as maturation selection bias can start from U9?

Can the ECB urgently measure how maturation selection bias works in the girls pathway?

Age Ordered Numbered and/or Coloured Bibs offer a way to show the level of (dis)advantage context to your context, when comparing player performance. It could be for Relative Age Effect, maturation status, training age or a weighted combination of all 3, or indeed anything.

Rob Reed
Rob Reed

Interested in Relative Age Effects & Maturation in Player Id & Development 🏏 #OneMoreSummer