Dear Dr. Kueh,

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PLOS One

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Additional Editor Comments:

Dear Author

thanks for submitting your article to PLOS ONE. Reviewers comments are provided below.

Please address them with mainly the addition of theoretical formwork for the study questionnaire to be expanded in the introduction.

Kind regards

Reviewers' comments:

Comments to the Author

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

Reviewer #1: Yes

Reviewer #2: Partly

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

Reviewer #1: Yes

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

Reviewer #1: Yes

Reviewer #2: Yes

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

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1:  The research is written in grammatically and scientifically correct language. The statistical analyses were accurate. It would have been preferable for the researcher to include a copy of the questionnaire as an appendix at the end of the research.

The exploratory factor analysis should have been performed before the confirmatory factor analysis.

The scientific references should have been arranged in accordance with APA7.

The discussion of the questionnaire appears to have been insufficient in terms of the theoretical framework underpinning its design.

Reviewer #2:  This manuscript tilted "Measurement and Structural Invariance of the Social Determinants of Health Questionnaire (SDH-Q) across Countries" is a cross-sectional study that explores the psychometric properties of the SDH-Q among 860 undergraduate medical students from Malaysia and Nigeria. While the topic is commendable and timely, several core psychometric and methodological concerns must be addressed to strengthen the validity of the findings.

1. Technically Sound (Replication & Rationale): Partly

The comparative approach between Malaysia and Nigeria is intriguing. However, the manuscript would benefit from a more robust theoretical rationale explaining the selection of these specific populations (for example, are there national indicators that underscore the practical importance?).

Furthermore, the authors must clarify the primary scope of this study: Is the objective to validate an instrument specifically for a medical student population, or is it intended for broader community settings to measure SDH? This is crucial in highlighting the importance of the research and in determining a concise research question.

In addition, the absence of a Pilot Study to establish Face Validity is a procedural gap. In cross-cultural psychometrics, pre-testing is essential to ensure that items are interpreted consistently across different linguistic and cultural landscapes.

2. Statistical Analysis and Sampling approach (Appropriateness & Rigor): Partly

The integrity of statistical outcomes is inseparable from the quality of the data inputs. Moving directly to a full-scale analysis without a pilot study introduces a high risk of measurement error. Thus, if the items were misinterpreted by participants, the resulting statistical models will be mathematically flawed regardless of their complexity.

Furthermore, there is a significant Sample-Concept Mismatch, as the inclusion criteria appear to be misaligned with the study's broader objectives. In addition, targeting medical undergraduate students to measure SDH tends to capture "academic perceptions" rather than the direct lived experiences of vulnerable populations, especially those who are most affected by these determinants. Without a preliminary validation to ensure cross-cultural equivalence between Malaysia and Nigeria, the statistical comparisons remain speculative and lack the necessary rigor for a conclusive psychometric study. The authors acknowledge information bias but there is a need to specifically address social desirability bias, which could be prevalent among medical students responding to psychosocial constructs.

4. Intelligible Fashion & Standard English: Partly

The manuscript's narrative is generally clear, but the introduction requires better thematic alignment. Specifically, the information regarding Sustainable Development Goals (SDGs) should not be presented as general background; instead, it must be strategically linked to the scale’s constructs and its field application. For instance, the authors should condense the broad descriptions of SDGs to focus exclusively on those most relevant to the study (e.g., SDG 3: Good Health and Well-being and SDG 10: Reduced Inequalities). This would allow more space to discuss the practical significance of the scale, specifically how its results can inform field-level interventions and evidence-based policymaking in Malaysia and Nigeria. From this perspective, the introduction needs to bridge the gap between global goals and the specific psychometric utility of the tool in identifying social health inequities.

The research question in the introduction lacks the necessary psychometric rigor and precision required to guide the validation process. It is vital for the authors to explicitly state the primary inquiry of the study early on, as this forms the foundation for the subsequent methodology and results. Moreover, there is a logical inconsistency in the introduction’s rationale. The authors justify the need for this study by citing Sabo et al. (2024) (P 5, paragraph 2, line 1; information cited from the reference [27]); however, the data collection for the current study was undertaken in 2023 (P 5, study design ( paragraph 1, line 5)). The authors should clarify this timeline or provide the original sources that informed the study's inception.

Final recommendation:

Decision: Major revision.

The manuscript addresses a timely and significant topic. However, it requires major revisions to align with rigorous academic standards. The methodology is compromised by the absence of a pilot study and misalignment between the target sample and the research objectives.

Furthermore, the authors need to clarify the logical inconsistency regarding the study's timeline and the references used. For the paper to be accepted, it is essential to demonstrate that the measurement tool is valid across different cultures and to better account for potential response bias. These improvements are crucial to ensure the validity and reliability of the findings.

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what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: Yes:  Amani Kubitary

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Measurement and Structural Invariance of the Social Determinants of Health Questionnaire (SDH-Q) across Countries.

PONE-D-26-22540R1

Dear Dr. Kueh,

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.

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Kind regards,

Taher Hatahet, Ph.D

Academic Editor

PLOS One

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

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

Reviewer #2: Yes

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

Reviewer #2: Yes

**********

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

The PLOS Data policy

Reviewer #2: Yes

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

Reviewer #2: Yes

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Reviewer #2: (No Response)

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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 #2: Yes: Amani Kubitary

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