Exploring Relationships among Crude Oil, Bitcoin, and Carbon Dioxide Emissions: Quantile Mediation Analysis

Round 1

Reviewer 1 Report

1.     The paper is interesting. It starts with a brief introduction of the literature in detail and focused on the discussed problem nicely.

2.     The methodology of the study seems to start very suddenly. The reader misses the chosen data description before the methodological discussions. So, a separate subsection of the data ad its extraction process is essential to include at the beginning part of the methodology section.

3.     The author may make a graphical presentation of data to prove the nonstationarity of the considered time series and then go for the related tests.

4.     The discussion section of the study should be placed before the conclusions.

 

5.     The conclusion section, in the present form, only highlighted the obtained results and efficacy of the novel approaches used in this study. However, some indications for policy implications, limitations of the stated methods, and future research scope should clearly be stated.   

 

Author Response

Response to Reviewer 1 Comments

Point 1: The paper is interesting. It starts with a brief introduction of the literature in detail and focused on the discussed problem nicely.

Response 1: Thank you for the reviewer's encouragement.

Point 2: The methodology of the study seems to start very suddenly. The reader misses the chosen data description before the methodological discussions. So, a separate subsection of the data ad its extraction process is essential to include at the beginning part of the methodology section.

Response 2: Thanks for your suggestion, it has been corrected as suggested by the reviewer. A separate section on data and its extraction process can be seen at 2. Methodology section–paragraph 1.

 

Point 3: The author may make a graphical presentation of data to prove the nonstationarity of the considered time series and then go for the related tests.

Response 3: Thanks for your suggestion, we have used “unit root test” to prove that the non-stationarity of the time series considered in the study is found. And then we have carried out the relevant tests.

In 3. Results section–upper paragraph of Table 3 and Table 3.

 

Point 4: The discussion section of the study should be placed before the conclusions.

Response 4: Thanks for your suggestion, it has been corrected. You can be seen at 4. Discussion section.

 

Point 5: The conclusion section, in the present form, only highlighted the obtained results and efficacy of the novel approaches used in this study. However, some indications for policy implications, limitations of the stated methods, and future research scope should clearly be stated.

Response 5: Thanks for your suggestion, it has been corrected.

In 5. Conclusion section–penultimate paragraph 2 and penultimate paragraph 1.

 

Reviewer 2 Report

Strengths:

1. The paper addresses a timely and relevant topic, examining the relationship between crude oil, CO2 emissions, and Bitcoin volatility.
2. The innovative use of quantile mediation regression provides a novel approach to analyzing these relationships.
3. The study adds to the growing literature on the environmental impacts of crude oil and Bitcoin mining.

Weaknesses:

1. The analysis does not include structural break testing, which could provide insights into potential regime shifts in the relationships among variables.
2. The paper lacks theoretical explanations for the expected relationships among variables, which would help readers understand whether the results are surprising or expected.
3. The language needs significant improvement, as the paper has many grammatical errors and awkward phrasings.
4. The introduction needs to be less abstract and provide clear examples or explanations of the problem being addressed.
5. Numerous incorrectly numbered citations and missing citations weaken the paper's arguments.
6. The paper needs to provide more detail on how variables are operationalized and the data sources used, raising questions about the validity of the analysis.
7. The authors must convincingly explain why Bitcoin would be used as a hedge for crude oil volatility.
8. There are errors in the presentation of econometric logic and potential misinterpretations of the results.
9. The use of quantile regression needs to be better justified, and the reasoning behind the curve shape change in the quantile results needs further explanation.
10. The discussion section contains normative claims not supported by the study's findings.

Suggestions to the authors and editors:

1. Perform structural break testing to investigate potential regime shifts in the relationships among variables.
2. Provide theoretical explanations for the expected relationships among variables and whether they can be considered linear or nonlinear.
3. Improve the language and grammar throughout the paper to enhance readability and clarity.
4. Make the introduction more concrete by providing clear examples and explanations of the problem being addressed.
5. Correct citation numbering and add missing citations to strengthen the paper's arguments.
6. Clarify how variables are operationalized, the data sources used, and the rationale behind using prices or quantities in the analysis.
7. Explain why Bitcoin would be considered a hedge for crude oil volatility.
8. Address errors in econometric logic and correct any misinterpretations of the results.
9. Provide a more explicit justification for using quantile regression and explain the significance of the curve shape change in the quantile results.
10. Revise the discussion section to focus on the study's findings, removing unsupported normative claims.

The paper presents an interesting approach to studying the relationship between crude oil, CO2 emissions, and Bitcoin volatility. However, numerous weaknesses in the analysis, language, and presentation of results need to be addressed. By incorporating the suggested improvements, the paper could provide a more convincing and robust analysis of the complex relationships among these variables.

See above

Author Response

Response to Reviewer 2 Comments

Point 1: Perform structural break testing to investigate potential regime shifts in the relationships among variables.

Response 1: Thanks for your suggestion, We add that the Chow test has been used to examine the possibility of regime shifts in the relationships among variables.

In 2.1 Chow test section.

In 3. Results section–upper paragraph of Table 1 and upper paragraph of Table 2.

In 4. Discussion section–paragraph 2.

 

Point 2: Provide theoretical explanations for the expected relationships among variables and whether they can be considered linear or nonlinear.

Response 2: The section on “linear or nonlinear providing theoretical explanations” has been added to Methodology 2.7 and Results.

In 2.7 Environmental Kuznets Curve (EKC) section–last paragraph.

In 3. Results section–upper paragraph of Table 8 and upper paragraph of Table 9.

 

Point 3: Improve the language and grammar throughout the paper to enhance readability and clarity.

Response 3: Thanks for your suggestion, we have requested MDPI to have the language and grammar re-edited by paid editors.

 

Point 4: Make the introduction more concrete by providing clear examples and explanations of the problem being addressed.

Response 4: Thanks for your suggestion, we have revised and added more examples and explanations in the introduction section.

In 1. Introduction section–paragraph 1, 2, 4, 5 and 6.

 

Point 5: Correct citation numbering and add missing citations to strengthen the paper's arguments.

Response 5: Thanks for your remarks, we have corrected the errors and added missing citations.

In 1. Introduction section–paragraph 4–correct citation numbering: [13], [14], [16], [17].

In 2.1 Chow test section–paragraph 1–added missing citations: [54].

In 2.3 Johansen cointegration test section–paragraph 1–added missing citations: [58], [59], [60].

In 3. Results section–upper paragraph of Table 8–added missing citations: [70].

In 5. Conclusion section–penultimate paragraph 2–added missing citations: [75].

 

Point 6: Clarify how variables are operationalized, the data sources used, and the rationale behind using prices or quantities in the analysis.

Response 6: Thanks for your suggestions, we have revised related content in the study.

In 3. Results section–paragraph 1.

Point 7: Explain why Bitcoin would be considered a hedge for crude oil volatility.

Response 7: Thanks for your suggestion, we have explained the reason why Bitcoin can be seen as a hedge for crude oil volatility.

In 1. Introduction section – paragraph 5.

 

Point 8: Address errors in econometric logic and correct any misinterpretations of the results.

Response 8: Thanks for your suggestions, we have revised and rewritten the related content.

In 2.7 Environmental Kuznets Curve (EKC) section – last paragraph.

In 3. Results section–upper paragraph of Table 6, upper paragraph of Table 7, upper paragraph of Table 8 and upper paragraph of Table 9.

 

Point 9: Provide a more explicit justification for using quantile regression and explain the significance of the curve shape change in the quantile results.

Response 9: Thanks for your suggestions. The results of “Chow test” have been used to provide a clearer rationale for using quantile regression, and also the importance of the nonlinear shape change in the quantile results has been explained.

In 4. Discussion section–paragraph 1, 2, 3, 4, 5 and 6.

 

Point 10: Revise the discussion section to focus on the study's findings, removing unsupported normative claims.

Response 10: Thanks for your important suggestions. We have revised the discussion section to focus on the research findings and removed unsupported normative statements.

In 4. Discussion section–paragraph 1, 2, 3, 4, 5 and 6.

 

Point 11: The paper presents an interesting approach to studying the relationship between crude oil, CO2 emissions, and Bitcoin volatility. However, numerous weaknesses in the analysis, language, and presentation of results need to be addressed. By incorporating the suggested improvements, the paper could provide a more convincing and robust analysis of the complex relationships among these variables.

Response 11: Thank you for your encouragement that has inspired our study. We have revised and rewritten many weaknesses in the analysis, language, and presentation of results. Therefore, We think that the revised study has provided more convincing and robust analysis of the complex relationships between these variables. We hope sincerely that the findings and implications of this study can make a contribution to the related research area.

Reviewer 3 Report

This study focuses on estimating carbon dioxide emissions from various energy sources. Crude oil and blockchain are chosen as the object of study. This study has not been previously conducted and is a promising direction. This study is quite interesting from both scientific and practical points of view. However, the work is not without flaws.

1. The structure of the work is broken. There should be a discussion section before the conclusion. Where would the authors show the positive and negative aspects of the study.

2. line 130. Before the "goal of this study" you must add the phrase "Problem statement"

3. I would recommend correcting the name, focusing not on bitcoin, but on the energy costs of its production. The name in this form the name is not correct for perception.

4. speaking of crude oil, it is necessary to note a completely different extraction technology in terms of cost. You can not compare the cost of production of light and heavy oil. Bitumen and oils with a high paraffin content have a high cost. It is necessary to note this in the work. I recommend including the relevant publication https://doi.org/10.1038/s41598-022-21778-0 in the literature review.

 

After eliminating these shortcomings, this work can be accepted for publication.

Author Response

Response to Reviewer 3 Comments

Point 1: The structure of the work is broken. There should be a discussion section before the conclusion. Where would the authors show the positive and negative aspects of the study.

Response 1: Thanks for your suggestion. We have moved the discussion section before the conclusion section. In addition, we have presented positive and negative aspects of the study.

In 4. Discussion section.

In 4. Discussion section – paragraph 3, 4 and 5.

 

Point 2: line 130. Before the "goal of this study" you must add the phrase "Problem statement"

Response 2: Thanks for your suggestion. We have stated “Problem statement” in the study.

In 1. Introduction section – penultimate paragraph 1: This study provides an innovative approach, we can accommodate both the mediation analysis proposed by Baron and Kenny [50] and Koenker and Bassett [51] with quantile regression. This approach can explore the dynamic causal effect of crude oil on CO2 emissions in short-term, regardless of its correlation with Bitcoin volatility.

 

Point 3: I would recommend correcting the name, focusing not on bitcoin, but on the energy costs of its production. The name in this form the name is not correct for perception.

Response 3: Thanks for your remark. We think that the focus of this study is to explore the correlations between crude oil, Bitcoin, and CO2 emissions using a new methodology. Therefore, the study does not directly address Bitcoin or investigate energy costs. On the contrary, we only address the mediation effect brought about by Bitcoin. But you gave good advice, so we put energy costs in the conclusion.

In 5. Conclusion section – penultimate paragraph 2.

 

Point 4: speaking of crude oil, it is necessary to note a completely different extraction technology in terms of cost. You can not compare the cost of production of light and heavy oil. Bitumen and oils with a high paraffin content have a high cost. It is necessary to note this in the work. I recommend including the relevant publication https://doi.org/10.1038/s41598-022-21778-0 in the literature review.

Response 4: Thanks for your suggestion. We think that the crude oil used in this study is based on Brent Light crude oil data, therefore, we ignore the production costs of light and heavy oil for simplicity. However, the authors agree with your suggestion that reducing crude oil production costs is also a good way to reduce CO2 emissions, and therefore, the publication you commended. (https://doi.org/10.1038/s41598-022-21778-0) has been included in the conclusion.

In 5. Conclusion section – penultimate paragraph 2.

Round 2

Reviewer 1 Report

Thank you for considering the revision. The methodology of the study is more clear now.  Discussion of the obtained results are clearly presented  that increased the readability. Best wishes.

 

Author Response

Point 1: Thank you for considering the revision. The methodology of the study is more clear now.  Discussion of the obtained results are clearly presented  that increased the readability. Best wishes.

Response 1: We highly value your appreciation of our work and your valuable feedback. Your encouragement is extremely important to us as it motivates us to continuously strive for improving the quality of our research.

Once again, thank you for your valuable feedback, and we wish you all the best!

Reviewer 3 Report

все замечания устранены. Рекомендую работу к публикации

Author Response

Point 1: все замечания устранены。Рекомендую работу к публикации. (all comments are fixed。I recommend the work for publication.)

Response 1: Мы ценим вашу оценку и ценные отзывы о нашей работе. Ваша поддержка очень важна для нас, так как она мотивирует наши непрерывные усилия по улучшению качества наших исследований.

Еще раз спасибо за ваши ценные комментарии, и я желаю вам всего наилучшего!

 

Response 1: We highly value your appreciation of our work and your valuable feedback. Your encouragement is extremely important to us as it motivates us to continuously strive for improving the quality of our research.

Once again, thank you for your valuable feedback, and we wish you all the best!