How to trial Age Ordered Bibs to reduce RAEs in cricket


Mann & Ginneken (2017) successfully used Age-Ordered Numbered Bibs in football to address Relative Age Effect. This is a summary of what a similar intervention in cricket would look like.


To run a scoping study in a single age group to discover if this intervention has utility in cricket trials. The study could subsequently be rolled out to cover a broader age range.


CAG U10 boys are recommended. Older age groups can be affected by maturation bias. In addition this cohort will not have been through a county selection process, where retention percentages may also be an issue. The cohort in Mann & Ginneken were U11 boys in football.

It is proposed to use a county that has open trials, i.e. no nomination effect from club coaches or any self-selections from parents/players. Circa 50 players.

A coaching cohort (n=12) from other counties with no knowledge of the players and a range of experience should be selected. 


Players can be evaluated through skill tests, a net context or in a match, whatever is the normal procedure. Essentially we don’t want to change anything apart from adding age-ordering.

Two trials are arranged on the same day in the same location. The first trial has the players, circa 25, in numbered bibs randomly assigned. The second trial, with the remaining players, circa 25, uses age-ordered numbered bibs with the oldest player with the lowest number (e.g. #1) and the youngest with the highest number.

Two groups of coaches are recruited, with 6 in each group. All 12 coaches watch both the first and second trials. One group is uninformed of any additional information while the other group is told that the players are numbered in age order (oldest is #1 etc). At the end of each match every coach reports a list of 16 players in order of potential.


The U10 player cohort should represent all of the birth quarters, from the same academic year, as evenly as possible, but this can be realistic.

Coaches are not allowed to converse or share information to avoid any groupthink effect.

Coaches who have been informed of the age ordering must not communicate this to any other coach.

Coaches with a mix of experience should populate each group.

Single colour bibs preferably numbered on both front and back are recommended. Some counties have used 4 colours to denote each birth quarter. This is not recommended.


Analysis should show a lower level of RAE from the informed coaches than the uninformed coaches for trial 2. Any bias between the coaching groups should be indicated by an analysis of the trial 1 results.



Very little cost. Numbered bibs are often already in use at CAGs & above.

Easy to implement. Easily understood.


No research evidence that this works in cricket yet. Only anecdotal evidence exists.

No evidence exists for utility for other age groups than U11.

Evidence only exists for boys football. This study is only designed for boys but should be duplicated in girls cricket subsequently.

No adjustments to the study regarding cricket’s specialised roles.


Could keep talented individuals within the game/pathways.

Could prevent RAEs at an early stage (prevention is better than cure).


Possible resistance from practitioners especially those with little to no understanding of RAE.


Age-ordered bibs are being used for training by Southampton FC for age groups up to U12s. They are also used, albeit for Maturation Status, from U12-U16. They have also been used at Worcestershire CCC for trials/training and I think there are plans to introduce them at Gloucestershire CCC.


A summary of Mann & Ginneken (2017), for use to address RAE and Ludin et al (2022), for use to address maturation selection bias.

Rob Reed
Rob Reed

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