Are birthdays really important - another look

Following on from our recent article investigating the Examiner's claim that your birth month will affect your chances of playing at international level for the Republic of Ireland, one of the issues that we had with the original study seemed to gather importance as the investigation continued, even after publishing the initial rebuttal

it[the initial article] ignores that summer soccer only started in Ireland in 2003, and not all of the players marked as "Irish reared" came through in this system.

With this in mind, we decided to examine the list of player we had included in the study again. As stated, summer soccer was only introduced in Ireland in 2003, therefore it was reasonable to assume that only players born after 1993 (who would be ten years old in 2003, and starting their football education) would have come through the youth setup in that environment. To date, the only players born in Ireland after 1st January 2003 that have made their international debut are Alan Browne (b. 15 April 2003) and Sean Maguire (b. 1st May 2003), and according to poster "Charlie Darwin" on Irish football forum foot.ie, the U19 league was still a winter league when Browne played there, leaving Maguire as the only international to have been "reared" (to use the Examiner's terminology) in the summer setup.

So, bearing these changes to the "development quarter" a player was born in (as opposed to the calendar quarter) how does this affect the study?

As you can see in the table below, there's now a more even spread of players between quarters one, three and four, with players born in quarter two (December, January and February) at a disadvantage when their chances of playing at international level are assessed. However, this quarter does include squad mainstays Shane Duffy, Glenn Whelan, Robbie Brady, Shane Long, Jeff Hendrick and Harry Arter.

Q1	Q2	Q3	Q4
Sept-Nov	Dec-Feb	March-May	June-Aug
13(25.49%)	11(21.57%)	13(25.49%)	14(27.45%)
Stephen Kelly(September 6) Kevin Doyle(September 18) Jonathan Walters(September 20) Ciaran Clarke(September 26) Cyrus Christie(September 30) Seamus Coleman(October 11) John Egan(October 20) Keiren Westwood(October 23) Darron Gibson(October 25) Alex Pearce(November 9) James McCarthy(November 12) Alan Judge(November 11) David McGoldrick(November 29)	Shane Duffy(January 1) Paul McShane(January 6) Glenn Whelan(January 13) Robbie Brady(January 14) Shane Long(January 22) Jeff Hendrick(January 31) Conor Hourihane(February 2) Sean Maguire*(May 1) David Forde(December 20) Harry Arter(December 28) Sean St Ledger(December 28)	Andy Boyle(March 7) Daryl Murphy(March 15) Aidan McGeady(April 4) Stephen Quinn(April 4) Paul Green(April 10) Alan Browne(April 15) James McClean(April 22) Callum O'Dowda(April 23) John O'Shea(April 30) Robert Elliot(April 30) Darren Randolph(May 12) Wes Hoolahan(May 20) David Meyler(May 29)	Anthony Pilkington(June 6) Shay Given(June 20) Robbie Keane(July 8) Jonathan Hayes(July 9) Eunan O'Kane(July 10) Damien Delaney(July 20) Anthony Stokes(July 25) Andy Reid(July 29) Stephen Gleeson(August 3) Richard Keogh(August 11) Daryl Horgan(August 10) Marc Wilson(August 17) Kevin Long(August 18) Stephen Ward(August 20)

* designates player developed in summer soccer

Armed with a better definition of when the quarter in which a player is born, we can now apply this definition across the history of players capped by the Republic of Ireland

Firstly, lets compare the record of players selected by Martin O'Neill to every player capped. There is a slight difference across the first three quarters, with increases in quarters one and two offset by a decline in the number of players born in Q3 selected for international honours.

Q	Players
1	94(28.14%)
2	75(22.46%)
3	73(21.86%)
4	92(27.54%)

Finally, let's look at players with ten, or more, caps. In our opinion, this gives the clearest indication of how the birth month of a player affects their chances of becoming a squad regular. Those players born in Q1, Q3 and Q4 have approximately the same chance of keeping their place in the squad, but players born in Q2 (December, January and February) do appear to suffer in this regard.

Q	Players
1	43(25.90%)
2	39(23.49%)
3	42(25.30%)
4	42(25.30%)

As we said in the rebuttal, this does need further study. Of particular interest is how the change to summer soccer has affected player development, is there a change in the makeup of underage squads when you compare the squads from before and after the change to summer soccer?

As we noted, there's only one international player who had the entirety of his football education in the summer soccer era, so it may be some time before an accurate study on the effectiveness of the change can be made.