Stretched Exponential Survival Analysis for South Korean Females

Round 1

Reviewer 1 Report

This manuscript focused on studying the topic of lifespan among Korean females using a mathematical analysis.  I agree that this study can provide additional information in relation to practical implications for dealing with this issue in Korea.  However, some issues are concerned.  Here is my observation.

The author should briefly explain why stretched exponential model was selected to be adopted for the analysis.  The reader may need to know whether this method is appropriate to be used for this study. Source of data should also be disclosed in the manuscript. It is suggested to present the part of Survival analysis under the section of Results and Discussion For Figure 2, the author should also disclose the source of data for other countries.  Also, did such data be applicable to be used for the comparison of the current findings?  The author should further justify this issue. It is suggested to provide a brief summary in order to highlight key findings of the current study. For the part of discussion, the author may explore potential reasons in terms of social or cultural issues (e.g. daily habits).  This may easy to find out the differences between Korean females and other females from different countries. For Figure 4, it states that the maximum lifespan of Korean females will be declined.  It seems different from the current findings.  The authors is suggested to provide some elaboration on this issue. The author should also provide some practical implications of the current findings.                                                                                                                                                                                                        I hope the above comment is useful.  Many thanks for giving me this opportunity to review this manuscript.  Good luck. 

Author Response

A1. The author should briefly explain why stretched exponential model was selected to be adopted for the analysis. The reader may need to know whether this method is appropriate to be used for this study.

---Flexibility of a modified stretched exponential function, originating from an age-dependent stretched exponent, enables us to mathematically describe plasticity and rectangularity of survival curves. As suggested, this reason was added in Page 2.

 

A2. Source of data should also be disclosed in the manuscript. It is suggested to present the part of Survival analysis under the section of Results and Discussion.

---All the data sources were clearly presented throughout the text (Pages 3~9). As suggested, the Survival analysis was moved into the Results and Discussion (Page 3).

 

A3. For Figure 2, the author should also disclose the source of data for other countries. Also, did such data be applicable to be used for the comparison of the current findings? The author should further justify this issue.

---As suggested, the data sources for South Korea and other countries were clarified in Fig. 2 (Pages 5-6). I believe that the data are quite applicable for the comparative analysis of the characteristic life from the recent three decades.

 

A4. It is suggested to provide a brief summary in order to highlight key findings of the current study. For the part of discussion, the author may explore potential reasons in terms of social or cultural issues (e.g. daily habits). This may easy to find out the differences between Korean females and other females from different countries.

---As suggested, the first paragraph in Discussion was improved to summarize the highlight key findings (Pages 9-10).

 

A5. For Figure 4, it states that the maximum lifespan of Korean females will be declined. It seems different from the current findings. The authors is suggested to provide some elaboration on this issue.

---The maximum lifespan is a kind of hypothetical lifespan limits. The decrease of the estimate means that more people can reach the biological lifespan limit as expected to be 125 years. This point was added in Page 11.

 

A6. The author should also provide some practical implications of the current findings.

---The quantitative analysis of human survival curves and the comparative analysis between countries are achievable with the modified stretched exponential function. This point was added in Page 10.

Reviewer 2 Report

I think this is a nice piece of work and can be a nice contribution to the statistical literature with applications to modelling of life expectancy and population dynamics.

I only have 4 comments:

- I think the title is misleading and should be changed. It sounds like this work is proposing the modification to the stretched exponential distribution, but after reading the manuscript I realise this has been proposed in an earlier work, and here the author applies it to analyse real data.

- I detected the use of 'I' at some points in the manuscript. The author should check if the journal accepts this, or if references have to be done through 'we' or citing directly the previous work.

- In figure 3, why do some dots have vertical and/or horizontal error bars and others do not?

- I believe the word 'living' in the last line of the first paragraph of page 5 is incorrect. 

 

Author Response

B1. I think the title is misleading and should be changed. It sounds like this work is proposing the modification to the stretched exponential distribution, but after reading the manuscript I realise this has been proposed in an earlier work, and here the author applies it to analyse real data.

---The title was changed as “Modified stretched exponential function for South Korean female lifespan analysis”.

 

B2. I detected the use of 'I' at some points in the manuscript. The author should check if the journal accepts this, or if references have to be done through 'we' or citing directly the previous work.

---The word “I” was removed by modifying the sentences in the second paragraph (Page 2).

 

B3. In figure 3, why do some dots have vertical and/or horizontal error bars and others do not?

---All the dots have vertical and horizontal error bars, although some of the error bars are smaller than the symbol sizes. This point was added in Page 6.

 

B4. I believe the word 'living' in the last line of the first paragraph of page 5 is incorrect.

---Corrected as “South Korean women have lived longer.” (Page 5)

Round 2

Reviewer 1 Report

This manuscript shows some improvement when comparing with previous versions.  However, few areas may need to be further concerned.  Here is my observation.

1.  More background information should be provided to explain why this topic is so important for South Korean Females.

2.  As mentioned, a brief summary of findings is suggested to be provided.  I have read the first paragraph of the part of Discussion, but I cannot find the relevant information.

3. The author may elaborate potential reasons for explaining the findings according to Korean context.  That is, those reasons are only found in S. Korea but not in other countries.

4. The author is suggested to further elaborate the practical implication of the findings.  That is, how do different professionals undertake relevant practice which can benefit for S. Korea females based on the findings.

 

    I hope the above comment is useful, and thanks again for giving this opportunity to review this manuscript. 

Author Response

This manuscript shows some improvement when comparing with previous versions. However, few areas may need to be further concerned. Here is my observation.

A1. More background information should be provided to explain why this topic is so important for South Korean Females.

---More background was added in the first paragraph of Page 2 as: “South Korean female is an important model to understand current trends in human lifespan and a better survival analysis is required for a better understanding of human lifespan.”

A2. As mentioned, a brief summary of findings is suggested to be provided. I have read the first paragraph of the part of Discussion, but I cannot find the relevant information.

---The first paragraph of Discussion (Page 10) and the Featured Application (Page 1) were improved as: “Now, it is noteworthy that the stretched exponential survival analysis enables the quantitative and comparative study of female lifespan between South Korea and other countries, particularly quantifying the survival rate, the characteristic life, and the maximum lifespan. …”

A3. The author may elaborate potential reasons for explaining the findings according to Korean context. That is, those reasons are only found in S. Korea but not in other countries.

---This comment was added in the second paragraph of Discussion (Page 11) as: “The potential reasons for South Korea may be plausible but not for other countries.”

A4. The author is suggested to further elaborate the practical implication of the findings. That is, how do different professionals undertake relevant practice which can benefit for S. Korea females based on the findings.

---As for the practical implication of this study was added in the last paragraph of Discussion (Page 11) as: “The practical implication of this study is that the potential reasons of South Korea may be useful to improve human lifespan, suggesting a further application of the stretched exponential survival analysis to identify personal, social, and environmental factors on human lifespan.”