PONE-D-22-09363Luxembourg’s open-door player selection policy reduces the risk of a relative age effect in youth footballPLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors' research question is well defined and supported in the statistical analyses presented.

The study does not prove the identified cause for the inexistence of RAE in Luxembourgish youth football. It only proves the non-existence of RAE, not the cause, as suggested by the title of the article: "Luxembourg’s open-door player selection policy reduces the risk of a relative age effect in youth football".

The only suggestion I would make to the paper is to introduce 1 or 2 charts showing the results, as they make the paper more appealing.

To make the title of the paper truly match the results it should be something like: " Luxembourg's youth football teams exhibit a negligible relative age effect".

Reviewer #2: Thank you for the opportunity to review this article. The paper addresses a novel under-researched are. However, there are some questions that need to be addressed to the manuscript.

KEYWORDS

Please, avoid using the same words of the title in the keywords.

INTRODUCTION

The introduction section is clear and well-written. However, it is necessary to elaborate a paragraph explaining in depth the relationship between RAE and performance in both genders.

MATERIAL AND METHODS

Name “under” before. (line 97)

Add the year of the Declaration of Helsinki (line 104)

Are these years correct? (line 141)

“p” in italic (line 157)

DISCUSSION

The discussion is clear and consistent. Great job! However, where the discussion of female results? Please, include it.

Relative age effects need to be abbreviated. (line 207)

Add population (line 233)

What will happen to these talented players if they cannot enhance their performance for this reason? Maybe, they would not be able to be successful in the future? This idea is not good for the reader... Please, discuss it. (line 233-234)

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Reviewer #1: No

Reviewer #2: No

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Low prevalence of relative age effects in Luxembourg’s male and female youth football

PONE-D-22-09363R1

Dear Dr.  Hülsdünker,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Rafael Franco Soares Oliveira

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Congratulation to all authors. My recommendation is to accept.

Best regards

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This is a study that characterizes the reality of Luxembourg's youth football teams regarding the phenomenon of RAE, based on the age of the athletes, namely if they were born in the first or second semester of the respective year. It is a comprehensive study in terms of age groups from U7 to U19.

The phenomenon according to the authors is more noticeable as the levels of competition increase, which is natural, so here the conclusion they reach is not a novelty, but corroborates the existing literature. It would be interesting in future studies for the authors to try to discover how to overcome this phenomenon.

Reviewer #2: Congratulations on a much improved manuscript

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Antonio Trigo

Reviewer #2: No

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