PONE-D-21-02736

Determinants of Fertility Rates in Selected Pacific Islands Countries: A Multi-Level Empirical Study

PLOS ONE

Dear Dr. Lal,

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.

The topic covered in the article could be an interesting read for researchers. The manuscript attempts to explore the nuances of various indicators on fertility in selected six Pacific Islands countries. The manuscript is excessively lengthy and severely lacks coherence in both the introduction and discussion section. For example, sentences between lines number 68-94 are poorly written and can be considered for deletion. Similarly, at various places in the manuscript, authors have failed to maintain consistency and coherence in the sentences. 

The acronyms used in the analysis need to be expanded when introduced in the manuscript—besides, the authors need to seriously check the in-out referencing. For example, WDI (2017) and Stock and Watson (2008) are not listed in the reference list. This article falls short on various grounds. 

In the process of empirical assessment, a range of statistical models have been applied in this manuscript; however, it falls short in terms of argument building and justification on the choices of these econometric models and, most importantly, in referencing. The review of the analysis in the study are as follows,

1. The methodology section of the manuscript is very confusing and needs serious attention. The authors have mentioned that both primary and secondary data sources have been carried out in the study. However, details on primary data source such as selection of households, sample adequacy, sampling design, statistical power are entirely missing from the analysis. The authors have selected 30 random samples from each country; however, in the study, N is equal to 700. The sample from each county is mentioned as 140. This creates massive confusion on the validity of the analysis.
2. Who were the respondents in the survey? All women of reproductive age group 15-49 years or currently married women of the reproductive age groups. It would be suggested to consider rewriting the methods section in a more detailed manner.
3. The authors have explained a range of fertility theories in the literature review. However, in the analysis section, they have adopted indicators based on Davis and Blake (1956) and Ahlburg and Cassen (1993) to conduct analysis. Why so ? However, the later study finds no place in the literature review.
4. Another observation from the analysis is that the availability of knowledge of contraceptives by women is considered a proxy of the CPR for the micro-level data. Surprisingly, the authors did not ask whether the women were currently using contraceptives or not? Why so ?
5. The authors need to bring more clarity on the indicators chosen for the study. For example, what a reader should comprehend from the “Highest level of educational attainment of women”.  Instead, in the table “Level of education” variable is mentioned. Are these two variables same ? Similarly, what is the meaning of “unmet need of pregnancy” ? does refer to failure in conceiving due to primary or secondary sterility or infertility, infecundity, or simply a mismatch between actual and desired fertility levels. Consider using the name for the indicators, which do not create confusion to the reader.
6. It is highly recommended to provide frequency distribution or descriptive statistics against each explanatory variable so that readers can comprehend sample adequacy for any empirical analysis.
7. There are some shortcomings in describing the stepwise structure of the econometric models. What made the authors run these three OLS models on the survey data is absent in the study. The motivation of using different models should be underlined in the method section as to what hypothesis authors are attempting to testify through each model. 
8. The variable “the number of kids to the women” depends on the age of the women. The fertility levels are dependent on the age at marriage and exposure to future fertility. How authors have accounted for the offset while dealing with OLS model. Also, considering the nature of the dependent variable, why do authors not employ the Poisson regression model on microanalysis?
9. The authors have employed the GMM estimation procedure assuming endogeneity in the model. To substantiate the premise, authors have cited study carried out by Arellano and Bond (1991). However, if such endogeneity persists or not in the case of PIC countries has not been empirically testified. I would suggest authors perform either the Hausman test or the Durbin-Wu-Hausman test to assess endogeneity in the present study's context.
10. Since the study is based on several approximations and assumptions; therefore, authors must include a section on ‘Limitation of the study’.
11. Lastly, the authors have failed to justify the study's title in the abstract, rationale and discussion section.
12. Considering grammatical errors and spelling mistakes in the manuscript, an immediate suggestion would be to get this manuscript copy-edited by some professional editor. 

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We look forward to receiving your revised manuscript.

Kind regards,

Srinivas Goli, Ph.D.

Academic Editor

PLOS ONE

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Additional Editor Comments:

The topic covered in the article could be an interesting read for researchers. The manuscript attempts to explore the nuances of various indicators on fertility in selected six Pacific Islands countries. The manuscript is excessively lengthy and severely lacks coherence in both the introduction and discussion section. For example, sentences between lines number 68-94 are poorly written and can be considered for deletion. Similarly, at various places in the manuscript, authors have failed to maintain consistency and coherence in the sentences.

The acronyms used in the analysis need to be expanded when introduced in the manuscript—besides, the authors need to seriously check the in-out referencing. For example, WDI (2017) and Stock and Watson (2008) are not listed in the reference list. This article falls short on various grounds.

In the process of empirical assessment, a range of statistical models have been applied in this manuscript; however, it falls short in terms of argument building and justification on the choices of these econometric models and, most importantly, in referencing. The review of the analysis in the study are as follows,

1. The methodology section of the manuscript is very confusing and needs serious attention. The authors have mentioned that both primary and secondary data sources have been carried out in the study. However, details on primary data source such as selection of households, sample adequacy, sampling design, statistical power are entirely missing from the analysis. The authors have selected 30 random samples from each country; however, in the study, N is equal to 700. The sample from each county is mentioned as 140. This creates massive confusion on the validity of the analysis.

2. Who were the respondents in the survey? All women of reproductive age group 15-49 years or currently married women of the reproductive age groups. It would be suggested to consider rewriting the methods section in a more detailed manner.

3. The authors have explained a range of fertility theories in the literature review. However, in the analysis section, they have adopted indicators based on Davis and Blake (1956) and Ahlburg and Cassen (1993) to conduct analysis. Why so ? However, the later study finds no place in the literature review.

4. Another observation from the analysis is that the availability of knowledge of contraceptives by women is considered a proxy of the CPR for the micro-level data. Surprisingly, the authors did not ask whether the women were currently using contraceptives or not? Why so ?

5. The authors need to bring more clarity on the indicators chosen for the study. For example, what a reader should comprehend from the “Highest level of educational attainment of women”. Instead, in the table “Level of education” variable is mentioned. Are these two variables same ? Similarly, what is the meaning of “unmet need of pregnancy” ? does refer to failure in conceiving due to primary or secondary sterility or infertility, infecundity, or simply a mismatch between actual and desired fertility levels. Consider using the name for the indicators, which do not create confusion to the reader.

6. It is highly recommended to provide frequency distribution or descriptive statistics against each explanatory variable so that readers can comprehend sample adequacy for any empirical analysis.

7. There are some shortcomings in describing the stepwise structure of the econometric models. What made the authors run these three OLS models on the survey data is absent in the study. The motivation of using different models should be underlined in the method section as to what hypothesis authors are attempting to testify through each model.

8. The variable “the number of kids to the women” depends on the age of the women. The fertility levels are dependent on the age at marriage and exposure to future fertility. How authors have accounted for the offset while dealing with OLS model. Also, considering the nature of the dependent variable, why do authors not employ the Poisson regression model on microanalysis?

9. The authors have employed the GMM estimation procedure assuming endogeneity in the model. To substantiate the premise, authors have cited study carried out by Arellano and Bond (1991). However, if such endogeneity persists or not in the case of PIC countries has not been empirically testified. I would suggest authors perform either the Hausman test or the Durbin-Wu-Hausman test to assess endogeneity in the present study's context.

10. Since the study is based on several approximations and assumptions; therefore, authors must include a section on ‘Limitation of the study’.

11. Lastly, the authors have failed to justify the study's title in the abstract, rationale and discussion section.

12. Considering grammatical errors and spelling mistakes in the manuscript, an immediate suggestion would be to get this manuscript copy-edited by some professional editor.

[Note: HTML markup is below. Please do not edit.]

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

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

Reviewer #1: 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

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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: No

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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 introduction is quite long and readers may struggle to understand the research problem the authors are trying to address. It is not clear the research question(s) and the new knowledge the study will contribute

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Reviewer #1: No

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Attachments

Attachment

Submitted filename: comment_PONE-D-21-02736.docx

Socio-Economic and Demographic Determinants of Fertility in Six Selected Pacific Islands Countries: An Empirical Study

PONE-D-21-02736R1

Dear Dr. Lal,

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,

Srinivas Goli, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Authors revised the paper according to reviewers comments, thus I am recommending this paper.

Reviewers' comments: