. ▁players ▁Category : B irmingham ▁City ▁F . C . ▁players ▁Category : AF C ▁Ajax ▁players ▁Category : New ▁York ▁Red ▁Bull s ▁players ▁Category : V e ik ka us li iga ▁players ▁Category : L igue ▁ 1 ▁players ▁Category : P rem ier ▁League ▁players ▁Category : E red iv isie ▁players ▁Category : M aj or ▁League ▁Soccer ▁players ▁Category : F inn ish ▁exp atri ate ▁sports people ▁in ▁the ▁United ▁States ▁Category : TP - 4 7 ▁players <0x0A> </s> ▁The ▁term ▁relative ▁age ▁effect ▁( RA E ), ▁also ▁known ▁as ▁birth date ▁effect ▁or ▁birth ▁date ▁effect , ▁is ▁used ▁to ▁describe ▁a ▁bias , ▁evident ▁in ▁the ▁upper ▁e ch el ons ▁of ▁youth ▁sport ▁and ▁academ ia , ▁where ▁participation ▁is ▁higher ▁amongst ▁those ▁born ▁early ▁in ▁the ▁relevant ▁selection ▁period ▁( and ▁corresponding ly ▁lower ▁amongst ▁those ▁born ▁late ▁in ▁the ▁selection ▁period ) ▁than ▁would ▁be ▁expected ▁from ▁the ▁normal ised ▁distribution ▁of ▁live ▁birth s . ▁The ▁selection ▁period ▁is ▁usually ▁the ▁calendar ▁year , ▁the ▁academic ▁year ▁or ▁the ▁sport ing ▁season . ▁The ▁difference ▁in ▁m atur ity ▁- ▁which ▁can ▁be ▁extreme ▁at ▁young ▁ages : ▁a ▁six - year ▁old ▁born ▁in ▁January ▁is ▁almost ▁ 1 7 % ▁older ▁than ▁a ▁six - year ▁old ▁born ▁in ▁December ▁in ▁the ▁same ▁year ▁- ▁causes ▁a ▁performance ▁gap ▁that ▁pers ists ▁over ▁time . ▁ ▁The ▁term ▁month ▁of ▁birth ▁bias ▁is ▁also ▁used