Transition of Socio-Demographic Characteristics in Urban Areas by Applying a Topic Model to Small Area Units

Round 1

Reviewer 1 Report

This paper analyzes the socio-demographic transition characteristics of small regional units in Fukuoka metropolitan area and Kitakyushu metropolitan area from 2000 to 2010. The topic model is applied to the small area cell grid data on two sections, and the variation of the estimated common topic in the topic share is given. Map the theme sharing, clarify the spatial distribution of the theme, and analyze its transition between the two cross sections and other geographical features.

The innovation of this paper is to develop a topic model for mining text from documents, which can be applied to provide geographic data for geographic topics.  The proposed model is able to assess shifts in geographic themes.

Some questions in the manuscript are as follows:

1. What specific attributes and formats are included in the 34 attributes? The text is not clear.
2. The legend in Figure 4 and Figure 5 are inconsistent with the colors in the figures, so it is impossible to distinguish the meaning of the grid in the figure.
3. This paper deals little with sustainable development, but mainly with the development and application of Geographic information system technology. Therefore, ISPRS International Journal of Geo-Information is more appropriate.

Author Response

1. (34 attributes) In the original version, table 1 for the attributes was missing. The list of attributes is inserted and denoted.
2. (Wrong colors of the legend in topics) The colors in the legend in topics is changed as to correspond the figures. The modification is made for table 2 and 3 figure 4, 5 and 7.
3. (Relatedness to sustainability) We inserted a novel discussion sub section as 4.3, which discusses much about the land use sustainability related issues.

Reviewer 2 Report

Dear authors,

Dear editor,

Thank you very much for the possibility to read the manuscript “Transition of Socio-Demographic Characteristics in Urban Ar-2 eas by Applying Topic Model to Small Area Units” and know more about the Japanese reality.

The manuscript develops the methodology of topic model considering small area units in two metropolitan areas of Japan based on socio-demographic and land use characteristics. The subject is consistent with the scope of the journal. Despite the relevance of the subject, some serious aspects could require an in-depth review before its possible publication.

I now list the main constraints of the manuscript in its current form:

1. ABSTRACT - A huge portion of the abstract is about the methodology. My advice is to sharp the methodology phrases, clarify the objectives of the study and reinforce the results and conclusions, as this manuscript is not only a methodological discussion;
2. The manuscript does not present a clear objective. The contribution of the work for science or for planning is not explicit;
3. The introduction is very little supported in the literature on the subject when this is quite extensive at world level. The first reference appears only in line 56;
4. The used dataset dated from 2000 and 2010 (quite outdated). Authors must justify this outdatedness (there is no more updated data? are these data still representative of reality?);
5. Some illustrative elements need to be reshaped. For example, figures 4 and 5 do not present the scale, north arrow, and the symbology in the maps are not equal with the table that accompanies the figures, if it serves the caption. Same with the figure 6, about the lack of mapping elements. In this case, only one legend is necessary.
6. The subsection 4.2. Discussion present results (eg. table 4) and do not provide what is expected in this section, as presented in the guidelines of the journal: “Authors should discuss the results and how they can be interpreted from the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted”;
7. In the discussion section, some literature support is missing about the comparison of other studies results, as it is missing the limitations of this work;
8. The bibliography is quite scarce considering the great discussion about the subject (13 references). Authors should make a general review of the bibliography formatting as it does not follow the journal's norms.

Other minor aspects:

• Topic model and Japan could be present as keyword;
• Figures and tables “should be placed in the main text near to the first time they are cited” as asked in the formatting guide (this aspect should be check for all elements);
• Figures and tables should be cited in the text as Figure 1, Table 1;
• 1 needs the identification of the symbology;
• The total amount of population in 2000 and 2010 for both metropolitan areas was not mentioned;
• Figures 4/5/6: the titles should include the metropolitan areas. Title of figure 6 should be corrected – reference year;
• In the line 324 it is discussed the dynamics based on the railway line. This element should be present in the legend of the map;
• The Table 3 referred in the line 355 do not represent what is explained in the text;
• There are some typos or split words that can be easily corrected by proofreading the text.

In this sense, despite the importance of the theme and the discussion of results for the Japanese case, with the possibility of methodological replication for other cases, in the current state, the manuscript is not ready for publication. It is suggested that authors carry out an in-depth review so that the manuscript has scientific quality for publication.

Author Response

1. (abstract) Following to the suggestions of reviewer, the abstract has been changed to make it clear that the proposed model can be used to properly capture the phenomenon of suburbanization.
2. (clear objective) The purpose of this study is added in the paragraph from the line 111 to 125.
3. (Introduction section and references) 9 papers are added and cited in introduction
4. (Dataset dated from 2000 and 2010) The reasons for using this period are explained in line 280 to line 291. For testing of model performance, we selected the period with contrastive population dynamics in Fukuoka and in Kitakyusyu.
5. (illustrative elements) Improved.
6. (section 4.2) Following to the purpose of this study, we change the chapter structure as follows; 4.1 Naming to geographical topics, 4.2 Characteristics of the estimated geographical topics, 4.3 Discussion from the estimated geographical topics. Such the alternation gives more clear understandings of  our study.
7. (reference to the conventional studies in discussion section) Since our purpose is to show the model performance, we did not cite the policy implications of conventional studies. Instead, we demonstrated possible discussions based on geographical topics. Instead, 2.4 is inserted to explain the methodological advantage of our model, and the condition to confirm the effectiveness of the proposed model, which are discussed in section 4.1 and 4.2.
8. (bibliography) 8 reference are inserted and the reference style are improved.
9. Other minor suggestions are improved.

Reviewer 3 Report

Dear authors,

The reviewed article concerns the use of socio-demographic data to assess the scale of spatial change in urban areas. The presented article is part of the current studies about morphology of urban areas using small spatial units (e.g. 1 km²). This type of research provides precise results on changes taking place in urban areas; it allows defining phenomena in agglomeration (e.g. urban sprawl) and at the same time evaluating changes (positive vs. negative).

I have no doubt that the article is methodologically very good, addresses an up-to-date topic, and is worth publishing in Sustainability. Before doing so, however, the authors would do well to consider making the following corrections:

1. To ground the research more firmly in the literature. The article is based on 13 publications, and I found the first literature reference in the fifth paragraph of Introduction. This is not sufficient for articles in journals with IF. The tenuous embedding of the research in the literature has its consequences in the Discussion section - but I write about that in the second paragraph. My recommendations for the literature are two. The first, each paragraph must have footnotes. This includes also the first paragraph of the Introduction, where you write that suburbanization began in the 1960s. The first paragraph is just an example on my part: does the 1960s refer to suburbanization in Japan or in the world? According to what sources do you think since the 1960s; one can easily find sources pointing to the 1950s of suburbanization in the US. The second recommendation is to write in Intro. 2-3 paragraphs on the nature of suburbanization processes and the specifics of measuring suburbanization. I see your paragraph (line 59-89) on methods, but you need a presentation of research that you can refer to in the Discussion. There are numerous studies on similar topics, starting with the well-known study: Galster et al. „Wrestling sprawl to the ground....”
2. Prepare an appropriate Discussion section. As it stands, Section 4.2 Discussion is not a discussion, but a inference of the results of the study. Hence, this part of the text should be included in 4.1 (then titling 4.1 loses its meaning; and the whole section 4 should be titled as Results). The discussion should include your thoughts on the research presented (including the method) in comparison to other research you mention in the Introduction. Footnotes will be needed here. It would be good to describe in the Discussion how your study develop current research on urban morphology. I can see the added value of your article, but you need to articulate this specifically in the Discussion.
3. Since your method is very interesting and I think it can be often cited and used empirically, it is worth adding a short description of the limitations of the method in the Conclusion. The idea is that other researchers using your approach should be aware of possible shortcomings. Pointing out the shortcomings in this way only shows the scientific maturity of the researchers. I have one more minor remark: I find Japanese language notations on the maps - you should make a correction to English or remove the notations.

My critical comments do not change the very high evaluation of the article. I consider it worthy of publication, however I would be happy to see a more perfect form of it. I congratulate the authors and wish them good luck in further development of their research.

Author Response

1. (Grounding to literature) Thank you for very concise recommendation. I added 9 papers as reference and they are cited in introduction. In line 112 to 126, I added the purpose of study and working hypothesis on this study. In terms of sprawl phenomenon and discussion address, I gave up to follow your suggestion because of time limitation. Instead, I added 2.4 to discuss the feature of proposed method related to the sprawl indices by Galster et al.
2. (reorganizing section 4) Thank you again for your suggestion. Again, due to time limitation and my less experience on footnote use, I have only reorganized the section. The discussion to validate the proposed methodology is mentioned with its evidence in 4.1 and 4.2.
3. (limitation and map alteration) Thank you again for kind suggestion. I added a limitation of current approach in the last paragraph. Unfortunately, I and co-author got influenza during the response period, we could not correct the maps. In the period for next round, we can surely correct it to fulfill your expectation.

Round 2

Reviewer 1 Report

No further comments. 

Reviewer 2 Report

Dear authors,

Congratulations for the hard work towards the clarifications. In my perspective, in the actual form, the manuscript present the conditions to be publish.

Best regards.