PONE-D-23-23392Family Structure and the association with physical activity – findings from 40 Countries participating in the Health Behaviour in School-aged Children (HBSC) StudyPLOS 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: Yes

Reviewer #2: Partly

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

Reviewer #1: I Don't Know

Reviewer #2: No

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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: No

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

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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: Dear Authors,

this is a well-written manuscript that needs only a few minor changes.

There are several places in the paper where you could use the abbreviation for physical activity (PA) instead of the full name.

Figure 2 and Figure 3 are a bit fuzzy and should be adjusted.

Please state the novelty and practical implications of your study.

Reviewer #2: Thank you for the opportunity to review this manuscript on family structure associated with physical activity in school-aged children. Please find my comments below.

My major concerns are as follows: (1) Not all factors associated with PA were controlled for; for example, caregiver’s BMI and PA could largely affect child’s BMI and PA, which is not accounted for in this paper; (2) a family structure could signal other issues in the family, leading to omitted variable bias on the family structure variable; (3) the countries in the sample are extremely varied and have very different SES levels and community supports for family and PA (including built environment, sports facilities, school curriculum) – it is possible that fixed effects are too limited to account for these differences; (4) ORs in a model with a non-rare outcome over-inflates the relative risk and should not be used.

More detailed comments are below.

I wonder if variance decomposition could be used to see how different family structures contribute to the variation in PA (compared to other variables).

Line 149: If having parent + stepparent was included as a separate binary covariate in the regression, the model assumes that one can have one parent and parent+stepparent at the same time (which is impossible). I wonder if “parent + step parent” should be included as a fourth category in the main covariate (one parent, 2 parents, parent + step parent, no parents). This could also be done in a separate model.

Line 170: Would it be possible to treat MVPA and VPA as a continuous variable as a supplemental analysis? Dichotomizing a variable leads to some loss of information, and ORs often represent an inflated measure of risk.

Line 180: Odds ratios (as mentioned above) represent an inflated measure of risk. While logit models are appropriate for use with binary variables, odds ratios can only be used to approximate relative risk when the outcome is rare. In the descriptive statistics, the outcome ranges from 9% to ~30%, making this not a rare outcome. In this case, authors should estimate relative risk instead of using odds ratios. Given that authors used Stata, it is very straightforward to obtain measures of both absolute difference in risk and relative risk from any model, including logit. Please refer to the following publications for methods:

Kleinman, Lawrence C., and Edward C. Norton. "What's the risk? A simple approach for estimating adjusted risk measures from nonlinear models including logistic regression." Health services research 44.1 (2009): 288-302.

Norton, Edward C., Morgen M. Miller, and Lawrence C. Kleinman. "Computing adjusted risk ratios and risk differences in Stata." The Stata Journal 13.3 (2013): 492-509.

Line 198: I wonder if the authors have attempted to test other ways of controlling for country differences. The sample includes extremely different countries with different supports for families and PA. It would make sense to test for both fixed and random effects, as well as looking at certain regions separately. I would like to see some evidence that a fixed effects model is the best model for this type of sample.

Line 195: Why wasn’t the country-level SES used in the models? What about other household characteristics (such as age, gender, BMI, PA of primary caretaker, BMI of the child, etc)?

Line 195: It would be helpful to clearly list all models with all of their covariates in each model; otherwise, it is hard to understand what covariates were included and how – from the Statistics paragraph as written. Perhaps include this as a supplemental table if there is no space in the text.

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Reviewer #1: No

Reviewer #2: No

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Family Structure and the association with physical activity – findings from 40 Countries participating in the Health Behaviour in School-aged Children (HBSC) Study

PONE-D-23-23392R1

Dear Dr.Melingen Haug,

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,

Zulkarnain Jaafar

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 #3: 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 #3: Yes

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

Reviewer #3: I Don't Know

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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 #3: 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 #3: 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 #3: The topic of this research article is interesting. and I can see that the authors have made an effort to address all the comments of previous authors.

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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 #3: No

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