PONE-D-21-07364

A systematic review and meta-analysis of the associations between interparental and sibling relationships: Spillover or compensation?

PLOS ONE

Dear Dr. Zemp,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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We look forward to receiving your revised manuscript.

Kind regards,

Livio Provenzi

Academic Editor

PLOS ONE

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Additional Editor Comments (if provided):

Dear authors,

two independent reviewers have now revised your submission.

They agree in highlighting several merits of your review and meta-analysis.

Nonetheless, they also raise one major issue related to the theoretical framework adopted and they additionaly suggest minor edits that may improve your manuscript.

Thus, please submite a revised version of your manuscript alongside a point-by-point response to the reviewers' comments.

Sincerely,

Livio Provenzi

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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: Yes

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: Yes

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: This is a very well-written manuscript describing a meta-analysis examining the relation between interparental relationship quality (IPR) and sibling relationship quality (SRQ). Their aims were clear and I liked that they couched the work within a family systems perspective and put two competing hypotheses out there that could, and have been, used to explain the relation between IPR and SRQ: the spillover or compensatory hypothesis. There has been some speculation for years that a positive sibling relationship can buffer the effects of interparental conflict, but I don’t believe anyone until now has examined this assumption in a meta-analysis so the information here is timely and could make a contribution to the field.

I very much enjoyed reading this paper and found it quite informative.

I have some very minor comments for the authors that might help clarify some of their procedures and decision-making when conducting the meta-analysis.

Given the central focus on IPR, I think it is important from the start to define or describe what they are including here under the IPR category. It may seem obvious to some, but I wasn’t clear what the inclusion criteria were here. For instance, martial relationships clearly would be included, and one of their moderator variables was cohabiting versus non-cohabiting, so there was some consideration of residence. Many would consider the coparenting relationship to be perhaps a central feature of IPR but it appears that the coparenting literature was not examined here or included, so the question I have is why not? Why would the coparenting literature not be included as part of a meta-analysis on IPR? Perhaps there are not many studies out there, which I could see might be the case. But, some justification I believe needs to be included because this was a glaring hole in my read of this paper. So noting up front how they are defining IPR and what is included seems essential.

Also, on p. 3 when introducing the three aims, perhaps they can just list in parentheses for aim 3, what some of the moderators are that will be included to inform the reader of what is to come. I found myself asking. What moderators?

I understand that certain decisions have to be made when conducting meta-analyses, but I also think there needs to be some note then in the limitations section of the implications of such decisions and how the findings might have differed. I’m thinking specifically of the decision to use data from the younger sibling for the sake of simplicity. I agree that such decisions need to be made, but the literature is also pretty clear that older siblings are more likely to be the leaders, managers, and teachers in sibling relationships, and one might argue protectors or instigators, so perhaps IPR would have a much stronger effect when examining the older siblings than the younger ones. Often times, it is what the older sibling is doing that determines the SRQ. Perhaps the authors would have found stronger effects for compensation if the decision was to extract information on the older sibling versus the younger sibling.

As a follow-up, I was a bit confused later on p. 11 when they claimed they coded sibling order of the index child to include whether they were the younger or youngest sibling or the older or oldest sibling. This seemed to contradict their earlier decision to extract data only from younger siblings. Some clarification here might be helpful.

I was also not clear on what search terms were actually used. I can understand that a large number of hits could be found using terms such as “child”, “maternal”, etc. But some information on the iterative process of refinement that was used would be helpful here as I was not clear what “broad terms not specific to dyadic relationship descriptions” were.

P. 13 ‘…studies were excluded because abstract analysis revealed they were unsuitable for the current review.” Again, could the authors simply provide an example or two here of what these situations were that led to exclusion.

Reviewer #2: Dear editor, thank you for the opportunity to revise the manuscript “A systematic review and meta-analysis of the associations between interparental and sibling relationships: Spillover or compensation?”. This is a very relevant study and has many strengths. The statistical analysis and the study description are very accurate, and authors provided all details and materials to allow study replicability. However, I think that there are major and minor issues that should be addressed. Here are some comments and suggestions that may help authors to further improve their manuscript:

Major point

• My main concern is about the choice and presentation of the theoretical framework (i.e. framework by Erel and Burman and spillover vs. compensation hypothesis). It seems to me that a more consistent replication of the framework by Erel and Burman about siblings’ relationship would be a meta-analysis about the link between parent-child relationship and siblings’ relationship, where the feelings experienced by a child in the relation with a parent may spill over in her/his relationship with the sibling. I agree with authors about the presence of a number of reasons to expect that positive interparental relationship quality is associated with positive sibling relationship quality, and vice versa, however not all of them would be explained through the spillover mechanism: spillover mainly refers to an indirect impact on other family members through affect spillover within a person from one family subsystem to another one (i.e. it is an indirect hypothesis about the impact of interparental conflict on child adjustment which is explained trough the deteriorating of parenting practices). Alternative hypotheses to the spillover one, support a direct impact of interparental conflict on child adjustment (e.g. the emotional security hypothesis and the social learning theory), however they are reported in this manuscript in support the spillover mechanism. Also the influence of third family stressors (p. 6 line 130) is reported here as a form of spillover, however it is better known in literature as “crossover effect” (e.g. doi: 10.1037/a0015977 “A third hypothesized process is crossover. Rather than a transfer of affect within one person across subsystems (i.e. spillover), crossover refers to the transfer of affect or behavior between people. An example of crossover is when the stress experienced by one partner at work is detrimental to the other partner’s relationship with a child”). I think that these theories refer to different mechanisms (though they are not self-excluding) and should be presented in a more consistent way in the manuscript.

Minor points:

• I suggest maintaining consistency throughout the paper in the presentation of goals to help the readers (they are presented as 2 or 3 goals in different manuscript’s sections).

• Did the author address the potential overlap between samples of studies by the same author (e.g. Stocker, Tucker, Ruff, Brody)?

• Please, deepen also theoretical implications of your results in the discussion section.

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Reviewer #1: No

Reviewer #2: No

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PONE-D-21-07364R1

A systematic review and meta-analysis of the associations between interparental and sibling relationships: Positive or negative?

PLOS ONE

Dear Dr. Zemp,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Sep 10 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Livio Provenzi

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments (if provided):

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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: (No Response)

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

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

**********

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

**********

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

**********

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: Thank you once again for letting me review this manuscript on the link between IPR and sibling relationship quality (SRQ). I appreciated the recognition that there may be different processes or mechanisms that might be responsible for any positive or negative associations between the two relationships, besides spillover or compensation. I did wonder in reading this version if the attempt to be so precise and restrict the spillover hypothesis to the affect contagion or behavior of one individual in the relationship to that same individual in a second relationship was so restrictive now, that some of the significance of the current analysis has been diminished.

I appreciate the clearer definition of IPR (the romantic, intimate aspect of the adult-adult relationship), and making it clear that they did not include coparenting. The problem however, comes back in the discussion when they want to interpret their results and keep referring back to parenting as a possible mechanism that explains the associations or mediates the IPR-SRQ associations. I think there needs to be some recognition in their discussion that the results may have been different if coparenting was the interparental relationship variable they used, and might even be a better test of spillover as it may very well include the parenting (or coparenting) mechanisms they would like to claim mediate the positive or negative associations. It is not clear from the current presentation why intimacy or conflict between adult romantic partners would be linked to SRQ,

I still believe there should be some mention in their discussion that results may have been affected by their decision to use information on the younger siblings when there were two or more siblings for the reasons I cited the first time (older siblings as leaders) or that they classified studies by the lower end of the age range. Making these decisions does not undermine the quality of the analysis done here or reduce the contribution it can make, but the limitations of one’s scholarly decisions should also be acknowledged.

Please specify by listing an example or two of what qualified as at-risk samples or clinical samples (bottom of p. 15).

I found the referral to moderators using letters (e.g., Moderator N) a bit frustrating as it meant I had to refer back to the table or text repeatedly to be reminded of what they were actually testing. Also, I could not figure out what moderator M was for some time, until I went back to the Intro as it is missing in the table and only referred to in their table note as Moderator M and only described in the text as Moderator M. I’m wondering if there might be some way to add some more descriptive information in the text as to what is actually being tested with moderators than relying solely on a letter descriptor.

I believe the discussion still needs some work. I understand they were criticized the first time by not being precise on what spillover was and appear to have now restricted it to relationships with the same individual, although I’m not sure everyone would agree with this strict definition. The affective arousal and emotion dysregulation children experience when witnessing parents argue in an emotionally charged conflict could very well carry over into interactions between siblings, and not be mediated by parenting. I think the work of Mark Cummings demonstrated this years ago.

“Another theoretical implication of this study relates to our impression that scholars often use different labels and operational definitions for similar constructs in this field. Inconsistence in the terminology and confusion in the conceptual operationalization of family relationships constitute a major challenge particularly for meta-analyses. We tried to avoid potential pitfalls by a prudent coding of the operational definitions of the different dimensions of relationship quality. However, the field would generally benefit from greater conceptual consensus.” (p. 26).

This section requires some more elaboration as to what point they are trying to communicate. Is the idea here that some researchers are measuring different constructs (e.g., some study aggression, others conflict or antagonism), or that they are using different means (observations, parent report) to assess the same construct (aggression)? I’m not seeing how this is a major problem, other than perhaps in trying to classify for a meta-analysis, as wouldn’t we have stronger evidence if the effect was there across multiple methods? And if it is such a major problem, then perhaps the authors may want to make some recommendations for how to remedy this in future work, other than just noting it is a problem.

I also didn’t follow their logic for why it was plausible for there to be more spillover processes in families with girls based on gender socialization. Stating it as such and explaining it are two different means of discussing the results.

I’m not sure their findings support the recommendations for a focus on the IPR for intervention. They were clear they were focusing on the intimate adult romantic nature of IPR but all their recommendations are about how parents should be provided the necessary skills to promote healthy sibling relationships. There seems to be a disconnect between what they did in their analyses and what they want to conclude from those analyses. Managing sibling conflict is a parenting (or coparenting) strategy, and not part of the intimacy of an adult romantic relationship. A couple-oriented relationship intervention to prevent child behavior problems via parenting would probably be a coparenting-intervention and there are some very successful coparenting interventions, but again, coparenting was excluded in the current meta-analyses.

I also think they need to be careful about making some overgeneralizations of the scarcity of programs focused on sibling aggression and conflict. Although there may be few, they do exist, and there are certainly many parent-focused interventions to reduce children’s disruptive behavior, which could certainly be applied here in the sibling context. I liked their example of the Triple P program.

Reviewer #2: Authors carefully addressed all my previous comments and have modified the paper accordingly. I think that they much improved their paper that is now more consistent also from a theoretical point of view. It is a high quality piece of work, congratulations!

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Reviewer #1: No

Reviewer #2: Yes: Serena Grumi

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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A systematic review and meta-analysis of the associations between interparental and sibling relationships: Positive or negative?

PONE-D-21-07364R2

Dear Dr. Zemp,

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.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

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Kind regards,

Livio Provenzi

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

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

**********

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

**********

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

Reviewer #1: Yes

**********

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

**********

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

**********

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: The authors have addressed all my comments and should be commended for conducting a very thorough and thoughtful meta-analysis on the links between IPR and sibling relationships.

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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: No