Exploration of Spatio-Temporal Evolution and Threshold Effect of Shrinking Cities
Round 1
Reviewer 1 Report
After carefully reading the manuscript, I think the topic of this manuscript is meaningful. The following should be carefully considered:
(1) Introduction
In line 102-106, the authors summarize the shortcomings of existing studies and point out that further research is needed that focuses on the characteristics of different regions and develops an approach to identify and analyze the causes of shrinking cities that reflects the "Chinese characteristics" However, the previous paper does not mention why the focus on different regional characteristics is necessary. And why the "Chinese characteristics" should be emphasized. What are the implications of studying urban shrinkage in the three northeastern provinces of China for other countries or regions? What is the contribution of this study?
(2) Lines 129-136. the authors mention the main topics that will be studied in this work. However, the presentation of these themes seems very abrupt. Why did the authors consider the THRESHOLD effect in the study design? What are the characteristics of existing studies or study areas that lead the authors to examine the influences of shrinking cities from the perspective of the threshold effect.
(3) Lines 248-255 Natural Dimension. The selection of impact factors for this dimension lacks the necessary literary support and foundation. We suggest the authors add to it. Also, line 252-253. why did not the authors directly choose air quality as the impact factor indicator? Or how about using urban green space? How can a direct relationship between the area of forests and grasslands and air and environmental quality be demonstrated?
(4) The Discussion section lacks a comparative discussion of the results of existing studies.
(5) What are the limitations of this study? The authors are asked to add this in the conclusion section.
(6) In addition, there are some typographical and formatting problems that need to be carefully checked and corrected by the authors. For example, the formulas in the text. There are still Chinese characters in the figure legends in the figures. The annotation section in Table 7.
Author Response
Response to Reviewer 1 Comments
Thank you very much for reviewing our manuscript and providing valuable feedback. Your comments have been tremendously helpful in improving the paper, and we sincerely appreciate your time and effort.
Below is our point-by-point response to each of your comments.
Point 1: (1) Introduction In line 102-106, the authors summarize the shortcomings of existing studies and point out that further research is needed that focuses on the characteristics of different regions and develops an approach to identify and analyze the causes of shrinking cities that reflects the "Chinese characteristics" However, the previous paper does not mention why the focus on different regional characteristics is necessary. And why the "Chinese characteristics" should be emphasized. What are the implications of studying urban shrinkage in the three northeastern provinces of China for other countries or regions? What is the contribution of this study?
Response 1 : Thanks for your valuable comments.
Regarding this specific comment from the expert, we have made the following modifications:
1.Optimization of the introduction:
Based on the suggestions, we have made significant revised to the introduction to improve its logical flow. The specific modifications are as follows:
（1）In the literature review section, we have included research on the development differences of shrinking cities in different countries and scales, such as East Germany, Poland, France, and the UK. This clarifies that there are variations in the development and formation factors of shrinking cities in different regions and scales.
（2）Emphasizing the scientific and necessary nature of the threshold regression. This model effectively identifies the thresholds, or boundary points, for different scales and measures the nonlinear relationships between variables.
（3）Incorporating the ongoing population decline in the Northeast China region. We have selected the threshold effect model to study the influencing factors of shrinking cities in this region.
2.Deletion of "Chinese characteristics" content and explanation of reasons:
We have deleted "Chinese characteristics" in this revision. In the initial draft, we included variables related to Chinese city administrative levels and city grades in the model. However, during the model setting process, these variables were either excluded from the model or did not exhibit significant significance. Therefore, we were could not reflect "Chinese characteristics" quantitatively, and thus we have removed this content in the current revision. We appreciate the expert's reminder.
3.Potential insights or contributions of this study:
This research has specific guiding significance for the development of shrinking cities in other regions of China. It can provide references for countries like Japan and South Korea, which are also part of the East Asian cultural sphere. The potential contributions of this study are as follows:
（1）Confirming the current status of shrinking city development in the Northeast China region and identifying different types of cities, urging relevant departments to formulate optimized policies or plans.
（2）Providing differentiated planning strategies for developing different types of cities in the Northeast China region to achieve optimal marginal effects.
（3）Offering insights for relevant cities as a point of reference.
Point 2: (2) Lines 129-136. the authors mention the main topics that will be studied in this work. However, the presentation of these themes seems very abrupt. Why did the authors consider the THRESHOLD effect in the study design? What are the characteristics of existing studies or study areas that lead the authors to examine the influences of shrinking cities from the perspective of the threshold effect.
Response 2 : Thanks for the valuable comments.
Regarding this specific point, we have made the following modifications:
A detailed description of the source of the topic was added in the introduction, highlighting the recognition of differences among shrinking cities of different scales, which led to the subsequent analysis.
There are three reasons for adopting threshold effect analysis:
- In the study of shrinking cities, we recognized significant differences among cities of different scales regardingwhether they are shrinking, the degree of shrinkage, and the factors influencing the shrinkage. Based on this observation, we concluded that the differences among cities of different scales may contribute to the variations in the formation of shrinking cities. Relevant experts have also acknowledged this viewpoint[1,2], and it was added to the introduction accordingly.
- Threshold effect analysis has the advantage of measuring parameter structural changes, allowing separate fitting of regression relationships within different intervals. The threshold effect model can effectively identify the nonlinear characteristics of urban development caused by scale. We provided relevant explanations in section 2.2.2.
- GDP is one of the most commonly used indicators to measure the scale of cities. We added supporting literature to strengthen this point[3].
This study selects GDP as the threshold variable for exploring threshold effects.
Point 3: (3) Lines 248-255 Natural Dimension. The selection of impact factors for this dimension lacks the necessary literary support and foundation. We suggest the authors add to it. Also, line 252-253. why did not the authors directly choose air quality as the impact factor indicator? Or how about using urban green space? How can a direct relationship between the area of forests and grasslands and air and environmental quality be demonstrated?
Response 3 : Thanks for the valuable comments.
In this revision, we have further explained the rationale for selecting the independent variables and included relevant literature to support our choices. This can be found in the modifications in Section 2.3.
Regarding the air quality indicator mentioned by the expert, we acknowledge its limitations in long-term time series analysis, such as large daily fluctuations, poor data stability, and susceptibility to external influences. On the other hand, using urban green space as a measure of the level of urban greening in the main built-up areas has its limitations in reflecting the overall environmental conditions of the locality. In comparison, forest and grass areas have functions such as gas regulation, climate regulation, and hydrological regulation, which can effectively maintain the stability of the local and surrounding ecosystems, as well as provide aesthetic landscapes and recreational spaces. Therefore, we have chosen forest and grass areas as important indicators for the natural dimension.
Point 4: (4) The Discussion section lacks a comparative discussion of the results of existing studies.
Response 4 : We extend our thanks to the expert for their insightful comments.
In this revision, we conducted an extensive literature review and incorporated relevant research discussions in the discussion section. Additionally, we supplemented the references accordingly. The main focus of the revision was on Section 4.2 and 4.3, where we compared and discussed the existing research findings.
Point 5: (5) What are the limitations of this study? The authors are asked to add this in the conclusion section.
Response 5 : Thanks for the valuable comments.
The limitations of this study mainly lie in the research scale, type identification, and selection of influencing factors. We have addressed these limitations and included relevant content in Section 4.4 of the main text.
Point 6: (6) In addition, there are some typographical and formatting problems that need to be carefully checked and corrected by the authors. For example, the formulas in the text. There are still Chinese characters in the figure legends in the figures. The annotation section in Table 7.
Response 6 : Thanks for the valuable comments.
The authors have conducted a thorough review and made corresponding modifications to the content, including formulas, figures, and annotations.
References:
- Turok, I.; Mykhnenko, V. The trajectories of European cities, 1960–2005. Cities2007, 24, 165-182, doi:https://doi.org/10.1016/j.cities.2007.01.007.
- Escudero-Gomez, L.A.; Garcia-Gonzalez, J.A.; Martinez-Navarro, J.M. What is happening in shrinking medium-sized cities? A correlational analysis and a multiple linear regression model on the case of Spain. Cities2023, 134, doi:10.1016/j.cities.2023.104205.
- He, S.Y.; Lee, J.; Zhou, T.; Wu, D. Shrinking cities and resource-based economy: The economic restructuring in China's mining cities. Cities2017, 60, 75-83, doi:https://doi.org/10.1016/j.cities.2016.07.009.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Please find the pdf document attached for detailed comments.
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 2 Comments
We would like to express our sincere gratitude for taking the time to review our manuscript and provide valuable feedback. Your expertise and insights have immensely contributed to improving the quality and clarity of our work.
Below is our point-by-point response to each of your comments.
Point 1: The connection of the research results with the globalization, post-industrialization, deindustrialization, resource scarcity, regional political turmoil, economic or functional structural disruptions, suburbanization, and the fragility of urban-rural systems in the north-eastern provinces of China must be discussed more in detail in the conclusion section of the paper.
Response 1 : Thanks for the valuable comments.
The modifications made in this section primarily focus on two aspects. Firstly, we have partially revisedthe content, replacing it with "globalization, resource scarcity, and suburbanization, among other factors," and analyzing the relevant cities in the introduction to align with the opening statement.
Secondly, during the analysis process, we found that this paper`s research scope, specifically China's three northeastern provinces, is particularly affected by resource depletion. Therefore, we have added relevant strategies in Section 4.2 to address this issue.
Point 2: Cumulative count (num-ber) classification spatial distribution, spatial distribution of population loss range (rate) classification, and the spatial distribution of shrinking cities types have been visualized in Figure 4 and Figure 5. These figures summarise the research findings in an understandable way, which is fine. However, if these figures are placed in the paperlarger, the inscriptions and legends on them can be read more easily.
Response 2 : Thanks for the valuable comments.
All images throughout the manuscript have been thoroughly reviewed for both format and content, and appropriate modifications have been made accordingly.
Point 3: These empirical studies (Eren, 2018; Zborowski, Soja & Łobodzińska, 2012) strongly support the statement given above so they can be cited:
Eren, F. (2018) Does the Asian property market work for sustainable urban developments?. Sustainable Cities in Asia. Editors: Federico CAPROTTI, Li YU. Routledge, pp.32-47. DOI: 10.4324/9781315643069-3
Zborowski, A., Soja, M., & Łobodzińska, A. (2012). Population trends in Polish cities: stagnation, depopulation or shrinkage?. Prace geograficzne, (130).
Response 3 : Thanks for the valuable comments.
“Eren, F. (2018) Does the Asian property market work for sustainable urban developments?. Sustainable Cities in Asia. Editors: Federico CAPROTTI, Li YU. Routledge, pp.32-47. DOI: 10.4324/9781315643069-3”
The mentioned book provides an overview of the development status of shrinking cities in Asian countries. hence it is referenced in the text [31].
“Zborowski, A., Soja, M., & Łobodzińska, A. (2012). Population trends in Polish cities: stagnation, depopulation or shrinkage?. Prace geograficzne, (130).”
The mentioned article offers a detailed description and analysis of the development of Polish cities following the collapse of socialism. Therefore, it is cited in the text [28].
Point 4: The literature section has not included some new empirical papers on shrinking cities, spatio-temporal evolution and influencing factors. I would like to ask the authors to see the papers published on this topic such as:
Long, Y., & Gao, S. (2019). Shrinking cities in China: The overall profile and paradox in planning. Shrinking cities in China: The other facet of urbanization, 3-21.
Yang, Y., Wu, J., Wang, Y., Huang, Q., & He, C. (2021). Quantifying spatiotemporal patterns of shrinking cities in urbanizing China: A novel approach based on timeseries nighttime light data. Cities, 118, 103346.
Döringer, S., Uchiyama, Y., Penker, M., & Kohsaka, R. (2020). A meta-analysis of shrinking cities in Europe and Japan. Towards an integrative research agenda. European Planning Studies, 28(9), 1693-1712.
Response 4 : Thanks for the valuable comments.
“Long, Y., & Gao, S. (2019). Shrinking cities in China: The overall profile and paradox in planning. Shrinking cities in China: The other facet of urbanization, 3-21.”
Chapter 1 of the book provides a comprehensive overview of the formation and development of shrinking cities in China, identifying the differentiated development status of different types of cities. Hence, it is referenced in [56].
“Yang, Y., Wu, J., Wang, Y., Huang, Q., & He, C. (2021). Quantifying spatiotemporal patterns of shrinking cities in urbanizing China: A novel approach based on timeseries nighttime light data. Cities, 118, 103346.”
The article evaluates the development status of shrinking cities in China based on nighttime lights data, confirming the high number of shrinking cities in the northeastern three provinces. Therefore, it is cited in [37].
“Döringer, S., Uchiyama, Y., Penker, M., & Kohsaka, R. (2020). A meta-analysis of shrinking cities in Europe and Japan. Towards an integrative research agenda. European Planning Studies, 28(9), 1693-1712.”
The article employs a meta-analysis approach to compare the development differences between shrinking cities in Japan and Europe, highlighting the influence of regional context on the development of shrinking cities. Therefore, it is referenced in [30].
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper explores the Shrinking Cities in Northeast China using spatial-temporal technics. There was a significant amount of work has been done. The paper is structured well. Existing studies have been referenced and discussed. However, the following issues need to be clarified before considering publishing:
1) The paper intends to investigate shrinking cities using country-level administrative units as targets. The authors need to clarify if only urban areas were considered or rural areas were also considered in this study;
2) The abstract needs to be more direct, e.g. Finally, panel regression models and panel threshold regression models are constructed for empirical analysis. It is suggested to be straightforward about what the empirical analysis is about instead of a vague expression
3) the authors need to clarify the data sources of each variable in Table 1. Where is the GDP, industrial output value, impervious, fiscal revenue and so on information come from? Yearbook?
4) in the discussion session, how does the current finding correspond with the literature? How does the finding of this paper contribute to the literature?
There is no major problem with the language, but do suggest getting the grammar and sentence structure checked
Author Response
Response to Reviewer 3 Comments
Once again, we extend our heartfelt thanks for your time, effort, and expertise. Your feedback has been instrumental in making our research more robust and impactful. We are grateful for the opportunity to benefit from your insightful evaluation.
Point 1: 1) The paper intends to investigate shrinking cities using country-level administrative units as targets. The authors need to clarify if only urban areas were considered or rural areas were also considered in this study;
Response 1 : Thanks for the valuable comments.
This study focuses on the county-level administrative units listed by the Ministry of Civil Affairs of the People's Republic of China. It covers both urban and rural areas and treats the entire region as a unified entity for research purposes.
Furthermore, corresponding explanations have been provided in Section 2.1 of the article.
Point 2: 2) The abstract needs to be more direct, e.g. Finally, panel regression models and panel threshold regression models are constructed for empirical analysis. It is suggested to be straightforward about what the empirical analysis is about instead of a vague expression
Response 2 : Thank you for your valuable insights and suggestions
This revision focuses on the following adjustments to the abstract:
- Emphasizes the results of the threshold effect test, highlighting the threshold characteristics of GDP.
- Due to the word limit requirements of the journal abstract (not exceeding 200 words), only a brief explanation of the results of the threshold effect regression model can be provided. A more detailed explanation of the regression results of the threshold effect model is provided in Conclusion 4.4.
Point 3: 3) the authors need to clarify the data sources of each variable in Table 1. Where is the GDP, industrial output value, impervious, fiscal revenue and so on information come from? Yearbook?
Response 3 : Thanks for the valuable comments.
The data for Section 2.3 is sourced as follows: Gross Domestic Product, Output Value of the Secondary Industry, Output Value of the Tertiary Industry, Investment in Fixed Assets, Fiscal Revenue, and Fiscal Expenditure are obtained from the "China County Statistical Yearbook" for the years 2000-2021. In cases where data is missing, adjacent years are used for supplementation.
Population size data is acquired from the Worldpop database.
Mean Annual Land Surface temperature data is processed using the Google Earth Engine (GEE) platform on MODIS/006/MOD11A1 continuous time-series data.
Impervious, Forest, and Grass data are derived from the China Land Cover Dataset. The data names have been optimized as Impervious Areas, Forest Areas, and Grass Areas.
Additionally, the data source is indicated in Table 1 of the main text.
Point 4: 4) in the discussion session, how does the current finding correspond with the literature? How does the finding of this paper contribute to the literature?
Response 4 : Thanks for the valuable comments.
This revision aims to further enhance the discussion section and provide a detailed analysis of the relevant literature, aligning with the broader findings in the literature. Mainly, we have made additional contributions in Sections 4.2 and 4.3 to explore the research outcomes of the relevant literature in more depth.
Author Response File: Author Response.pdf
Reviewer 4 Report
There is no doubt that you have conducted a meaningful study on the spatio-temporal evolution and threshold effect of shrinking cities. However, there are some weaknesses that require accurate inspection and review.
(1) The introduction section needs to emphasize the importance and significance of research. Moreover, the logic of the three paragraphs in lines 45 to 106 is unclear and needs to be optimized to better align with the review logic.
(2) There are some format problems that need to be carefully checked by the author. For example, the explanation of the formula in lines 163-167 does not require quotation marks; formula (2) font does not meet specifications......
(3) Please explain the reasons for choosing public finance expenditure and income as investment variables and forest and grassland area as natural variables.
(4) 2.3 variable selection and source section needs to further clarify the relationship between urban contraction and population contraction.
(5) Please elaborate on the process of using panel threshold regression models to identify different GDP threshold intervals in detail.
(6) Suggest splitting 3.4 into two parts, namely 3.4 threshold effect of influencing factors on shrinking cities and 3.5 regression analysis of influencing factors on shrinking cities.
(7) The discussion should further emphasize the innovation and significance of the paper, while also discussing the GDP threshold effect.
(8) The planning strategy for urban contraction in the discussion should be specific.
Author Response
Response to Reviewer 4 Comments
We carefully considered each of your suggestions and comments, and we have made significant revisions accordingly. Your thoughtful and thorough review has undoubtedly enhanced the overall strength and rigor of our research.
Point 1: (1) The introduction section needs to emphasize the importance and significance of research. Moreover, the logic of the three paragraphs in lines 45 to 106 is unclear and needs to be optimized to better align with the review logic.
Response 1 : Thanks for the valuable comments.
The revisions made in this round of modifications have significantly overhauled the introduction section, encompassing logic, content, and expression improvements.
The revised introduction follows the main logical flow outlined below:
1.Firstly, the widespread and pressing nature of shrinking cities is introduced, emphasizing the importance and significance of this research.
- Acomprehensive literature review is conducted on the identification, types, and causes of shrinking cities.
- The variations in shrinking characteristics and causes among cities of different scales are highlighted, leading to the introduction of the threshold effect.
- Lastly, this study`s research area and methodology are presented.
With these modifications, the introduction section has been enhanced in terms of logical coherence, content coverage, and overall clarity of expression.
Point 2: (2) There are some format problems that need to be carefully checked by the author. For example, the explanation of the formula in lines 163-167 does not require quotation marks; formula (2) font does not meet specifications......
Response 2 : Thanks for the valuable comments.
The formulas and their explanations have been revised, and careful checks and adjustments have been made to the formatting of the main text, headings, and figures.
Point 3: (3) Please explain the reasons for choosing public finance expenditure and income as investment variables and forest and grassland area as natural variables.
Response 3 : Thanks for the valuable comments.
Firstly, we explain the rationale for selecting fiscal revenue and fiscal expenditure. In China, fiscal revenue and fiscal expenditure are used to safeguard and improve people's livelihoods and promote economic and social development. Fiscal revenue refers to the actual financial resources available at the local level. In contrast, the functional classification of fiscal expenditure mainly includes expenditures related to general public services, social security and employment, urban-rural community affairs, and other aspects. These variables represent the local government's capacity in construction, renovation, investment, and maintenance and are among the key drivers of China's economic and social development and urban construction. Therefore, we selected fiscal revenue and expenditure as representative variables for the investment dimension.
Secondly, we selected forest and grass areas as one of the research factors. This is because forest and grass areas possess substantial ecological value, providing abundant oxygen supply for the population and playing a role in air purification. They also offer social services such as recreation, entertainment, and leisure. Considering these factors, we chose forest and grass areas as variables representing the natural dimension.
Regarding the above content, we made corresponding modifications in Section 2.3 of the main text and added relevant references.
Point 4: (4) 2.3 variable selection and source section needs to further clarify the relationship between urban contraction and population contraction.
Response 4 : Thanks for the valuable comments.
In this revision, we added relevant references in the introduction and Section 2.3 to support the argument of using population size to identify shrinking cities[1].
This study adopts a "two-step recognition method" based on population size data to identify shrinking cities. The purpose of this method is to achieve accurate identification of shrinking cities through a relatively robust approach.
To enhance the accuracy and scientific rigor of the analysis, we have incorporated three comparison groups based on population size as a distinguishing factor, building upon the results of the threshold regression analysis. This additional step further ensures the scientific validity of the research.
Point 5: (5) Please elaborate on the process of using panel threshold regression models to identify different GDP threshold intervals in detail.
Response 5 : Thanks for the valuable comments.
This revision provided detailed explanations in Section 2.2.2 Panel Threshold Regression Model, regarding the estimation approach, testing methods, and general form of the dual-threshold effect model.
In summary, the threshold effect is based on the ordinary least squares estimation approach, where hypothesis tests are conducted to determine the existence of the threshold effect and estimate the threshold values. As a result, different regression coefficients are obtained for different threshold intervals.
Point 6: (6) Suggest splitting 3.4 into two parts, namely 3.4 threshold effect of influencing factors on shrinking cities and 3.5 regression analysis of influencing factors on shrinking cities.
Response 6 : Thanks for the valuable comments.
This revision divides Section 3.4 into two parts: 3.4.1 Results of Threshold Effect Testing on Shrinking Cities and 3.4.2 Regression Analysis of Influencing Factors on Shrinking Cities. The rationale for this modification is as follows:
- The original content in Section 3.4 was extensive, and splitting it into two subsections improves clarity and understanding.
- Threshold effect testing and the analysis of threshold results are essential steps in the threshold regression model. These two parts have a sequential relationship and build upon each other.
Point 7: (7) The discussion should further emphasize the innovation and significance of the paper, while also discussing the GDP threshold effect.
Response 7 : Thanks for the valuable comments.
In this revision, emphasis was placed on the novelty of this study in both the introduction and discussion sections.
Point 8: (8) The planning strategy for urban contraction in the discussion should be specific.
Response 8 : Thanks for the valuable comments.
This study proposes targeted and step-by-step strategies for urban planning in shrinking cities based on the research findings and references to relevant literature. The modifications primarily focus on "4.3 Urban Planning Strategies to Tackle Shrinking Cities."
References:
- Danko, J.J.; Hanink, D.M. Beyond the obvious: A comparison of some demographic changes across selected shrinking and growing cities in the United States from 1990 to 2010. Popul Space Place2018, 24, doi:10.1002/psp.2136.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Thank you to the author's efforts, this version looks much better. There are only a few minor points that need to be revised and improved
(1) Line 204-206. The authors believe that the shrinking of cities is due to a combination of economy, investment and natural environment. This idea is very important and is the focus of this article. However, there is a lack of sufficient theoretical support here to prove the objectivity of this view. It is therefore recommended that the authors add appropriate references.
(2) The authors are asked to check the entire text for other minor errors. For example, the references in line258 Table 1, equation (2), etc. Could the indication in table 1 be expressed a little more precisely.
Author Response
Thanks once again for your support and assistance in our research. We highly value your feedback and understand the importance of your professional knowledge and experience in our academic development. We will carefully consider each of your suggestions and make every effort to ensure that our research meets the academic standards and journal requirements.
Point 1: (1) Line 204-206. The authors believe that the shrinking of cities is due to a combination of economy, investment and natural environment. This idea is very important and is the focus of this article. However, there is a lack of sufficient theoretical support here to prove the objectivity of this view. It is therefore recommended that the authors add appropriate references.
Response 1 : Thanks for the expert's feedback.
In this revision, the authors have extensively reviewed the literature and added additional references to enhance the theoretical support in selecting influencing factors of shrinking cities.
Point 2 : (2) The authors are asked to check the entire text for other minor errors. For example, the references in line258 Table 1, equation (2), etc. Could the indication in table 1 be expressed a little more precisely.
Response 2: Thanks for the expert's feedback.
In this revision, the authors have thoroughly examined the entire manuscript. We have addressed the specific points the expert mentioned and reviewed the main text, figures, equations, and references. Punctuation, spelling, and other details have been carefully checked.
Regarding the references in line258 Table 1, in this revision, the authors have ensured that each variable is supported by corresponding references to strengthen the theoretical basis for variable selection.
Regarding equation 2, the authors appreciate the expert's reminder. The incorrect superscript in equation (2) has been removed.
As for Table 1, in this revision, the authors added descriptive statistics to provide more accurate and detailed information.
