Harmonized Skies: A Survey on Drone Acceptance across Europe
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear authors,
Thank you for the opportunity to review your submission. First of all, the topic is relevant and very interesting, not only in general but also to my own field of research in which privacy concepts and technology interaction are heavily featured. I have also studied the public’s perception of the deployment of drones, whose versatility should be used on a broader scope and therefore this area needs more careful studies.
I will list my notes in order as they occurred while reading through the manuscript:
Already in the first sentence of the introduction, you lose people who are interested but maybe not up-to-date with drone regulations. Please insert a quick explanation of “U-space” and/or at least a comprehensive source for a quick update.
Next, you list different projects, but the hook of your research seems to be that the drone market is growing worldwide. Why should we care about that? Why are drones of interest? What do they offer? Why do they need to be studied? Please explain in the first paragraph of the introduction, before listing any projects and their specific scopes. The text beginning in line 33 is a much better hook and starting point for your paper contentwise, so maybe restructure the introduction accordingly.
Also, please specify early on which drones you focus on: what load can they carry and what is the maximum size of your scope?
While your state of research is rather short, it is a comprehensive summary of studies already conducted. However, as reader and researcher, I am unclear as to what the reason for conducting your study is. You jump from a short overview of previous research to your method and begin with the description of the countries you used and the questionnaire structure. There is vital information missing in your description. What was your research question? What is missing from previous studies and what do you hope to contribute with your research? What are possible hypotheses you could check? You don’t necessarily need clearly formulated hypotheses, but you need a clear research question and motivation for your study. The current manuscript does not offer that to the reader at this point.
In the section “Procedure”, you mention that some questionnaire items were based on a previous telephone poll. All right. But the other items concerning, for example, acceptance or attitude, need to have sources as well. Were those single items or did you use constructs? What were the ranges of your 7-point scales (e.g., 0 = do not agree at all to 6 = totally agree)?
How did you present the various flying altitudes? Did you use pictures? Different measurements in text form? Please elaborate at that point in the paper!
Personally, I would put general and overall analysis information before the sub-sections within that section. For one, you avoid two headings directly on top of each other. For another, you avoid unnecessary repetitions of, for example, the significance level or removal of missing values. Which leads to another question: What exactly does that mean? Did you remove incomplete datasets in general or just ignored missing answers for individual items?
Please describe your data-cleaning process in more detail, also concerning potential speeders and quality of answers. Did you use questions to check if your respondents paid attention and actually read the questions? Also, concerning data acquisition, did you use quotas and if so, which ones? Did you choose the six European countries, because the market research institute offered them/had access or did you use those specifically. And if so, why? (Going over my notes again, you mentioned your reasoning in the discussion. As you can see, this information needs to be given much earlier within the paper.)
Apparently, you aggregated several items to form a construct for “concerns.” How many items? Where did they come from (i.e., source)? Did you check reliability of your scale and if so, what is it? (You give this information in the results section, which, again, is too late within the context of a research paper.)
As a rule of thumb, the sample description is not part of the results. If it is not in a chapter of its own, the sample description is part of the method, as you used a specific approach to get your respondents/participants. And you used a market research institute, so you must have given some quotas they were supposed to fulfil.
Why are there no participants older than 65 years of age? Did you want almost equal numbers from each country? Did you consciously decide against a smaller mirror of the population of each country (concerning, e.g., age, gender, income, education)? How and why did you measure “interest in modern technology”?
Figure 2 includes the approval for “air taxi”. Yet, you have said on page 2 that you will not report on that section of the questionnaire. I think it is a completely different technology or “vehicle” that is used for research, parcel deliver, monitoring, photos and video. Those, in my experience, are much smaller and could not hope to carry a person or two. Again, please elaborate early in your paper the specifics of drones you study in this presented research. Also, how did you introduce your participants to the topic and described the drones they were supposed to evaluate?
As with the sample description, scale consistency does not belong within the results section (you have reported Cronbach’s alpha for concern in line 276, when it needs to be in the in chapter 3.2.3, thus approximately line 116).
In line 334, you mention “THE three fields of use” [the emphasis is mine] which you have mentioned once in line 133. Between those two occurrences, you have clustered civil & public as well as private & commercial. Yes, in the following sentence you offer the statistics for the use cases you meant, but by that time, the reader is already confused and trying to figure out which use cases are meant.
Considering the barely noticeable change in font size of your “Note” (in line 353) and the rest of the text, the asterisk in front of it suggests there is a word or sentence before that is given more information about with the note. According to the manuscript template, tables are allowed a footer, so use that for the information. Perhaps this is just a formatting issue, but the large space between the table and your “Note” without any previous asterisk to know a connection is confusing.
Figure 10 is missing important information: Please label the x-axis correctly!
In line 401, you refer to results “in chapters 3 and 4.” However, your result section is “chapter 4.” I would refer to these as sections and not chapters. And those sections have subsections. Please, correct the reference, especially add the correct numbers for the section/subsection you mean.
Figure 11 is very confusing. There are only numbers on the axes, no explanation what is measured on each axis. Both axes range to 7, however, the y-axis is skewed as it begins with 3 and not 1 as the x-axis does. You put the axis labels basically into the figure caption. That is not proper standard. Please label the axes in the figure correctly.
You used a line chart, even though the categories of some features are distinct and not continuous; you don’t “transition” from Germany to Poland to Austria in a linear way. For age, a line makes sense, for gender, knowledge, inhabitants_residence, and even experience, not so much. Also, it is somewhat tedious to flip between pages 13 and 14, where the numeric values of the features are, to page 16, where the figure utilizing this information is. Make sure, in the final print version, that the table fits on and is printed on a single page, so that leafing from one part of the text to the other is easier.
The discussion could and should be more than the summary of the results. Maybe due to the missing research question and motivation, this paper falls somewhat short in what it could present and offer. With carefully consideration and incorporation of the notes given by the reviewers, this could be a good addition to the research field and offer valuable insight into the future of drone deployment in different use cases.
You suggest some valid point to take from your results, e.g., privacy should be considered, more knowledge should be provided, more research should be done, but your paper would be elevated if you give some more detailed options, i.e., think a step further. What are possible scopes for “increasing knowledge”? (School subjects? Information events? Documentaries? Newspaper articles?) What should policy makers take on, for example to protect privacy of citizens and how should they communicate this, i.e., transparency?
Last notes:
All your figures are missing information in their captions. Please add the number of answers presented in the figures (i.ge., n=????) as well as the measure presented by the whiskers (which is probably standard deviation but it needs to be clarified and mentioned in each caption).
Additionally, do not use Excel’s chart title but instead add that information to the y-axis (except for figures 10 and 11 where the chart title is necessary to understand which chart shows which target variable). Nevertheless, all your charts need proper axes labels!
In my opinion, the readability of the bar charts could be improved if you added data labels.
Perhaps this stems from the current format but avoid line breaks within statistical equations, e.g., you write “M =” in line 197 and the numerical value in the following line; or “p <” in line 209 and its value “.001” in line 210. This happens multiple times within the manuscript and it impedes reading and returning to “quickly check the numbers.”
This paper needs some work to be fit for publication, but in terms of content, it could offer very interesting additions to this field of research.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear editor
Thank you for inviting me to review the paper 'Harmonized Skies: A Survey on Drone Acceptance Across Europe.'
GENERAL COMMENTS.
Public acceptance for drone transport has gained extensive interest. Despite an extensive literature, we still need more knowledge about this topic, and in particular, what significance public acceptance will have to the future implementation of drone services. Does it matter at all?
This paper may add some interesting research and deserves publication.
I have the following comments to the authors.
ABSTRACT
I strongly recommend that both the abstract and as well the discussion and conclusion highlights more clearly on the main findings of the study. As I observe it, the main results are that acceptance of drones is highly related to the knowledge of drones, and that attitudes to drones is more positive to "public and assumed societal valuable services", then for private or "for profit services". This should be a main statement in the Abstract. To underline this more explicitly in the abstract may prepare the reader during the extensive presentations of different parameters that, although they are significant different, may trigger reflections in the reader whether it has any real life significance at all. That should also be better discussed in the paper (my comments below).
The Abstract statement 'For this reason, future drone strategies should include extensive education and information campaigns to increase acceptance and reduce concerns among the population' is not justified by the current study and must be revised (see my comments to Discussion). To claim that such extensive actions, need data of the significance of public attitude for the implementation of drones. This is not discussed at all in the paper.
METHODS.
I have no indebt knowledge of all the statistical methods applied, but have some questions.
Dummy coded. 'Country, gender, and income have been dummy-coded'. Dummy coding uses 0 and 1. Numeric values as presented in Table 7 are not dummies. Please explain in detail.
I'm also very uncertain how the study objects have been able to interpret 'the minimum flight altitudes'. What is 'flying'? Is it vertical during take-off and landing, or is it horizontal during the flight of transport? Any drone landing will have to fly at minimum altitude of less than 10 m and down to zero. Why were these differing levels chosen? What is the overall real life significance of these differences?
Furthermore, in line 336 'commercial drones should obtain the highest altitudes'. A better phrasing may possibly be 'fly at high altitudes'? But what is the intention with this statement? This is not very clear to me. Do you really expect that drone space will be divided in corridors for public and private transport?
'The interest in modern technology is moderate to high across the sample'. How was 'modern technology' described to the responders? Did you only consider drones, or did you include other tech? Please explain. Only drones would not cover the term 'modern technology'.
Acceptance: 'Acceptance involves the target variable's attitude, concerns, and approval for private and commercial and public and civil use cases'. This tells me that the acceptance variable has several challenges, this should be better discussed in the Limitations/discussion part.
RESULTS.
The paper presents a lot of detailed measures that show statistically significant differences across countries and other parameters, but although these are significantly different, I'm rather uncertain whether this has any practical implication in real life.
A comment to Table 6.
The numbers of respondents with 'no experience, second hand experience and first hand experience' differs across the dimensions of public, commercial and private partition. These varying numbers of responders should be explained. Are these variations due to missing answers? In that case, how may the total number of participants be the same in the right column? This should be explained.
Age and knowledge.
Knowledge and age are predictors for several parameters. It would be interesting to know how many subjects are included in the age categories 1-4, and whether the levels of 'no experience', 'second hand experience' and 'first-hand experience' relates to the age of the subjects. It could be hypothesised that older age would relate to a lower level of knowledge and experience? A simple plot could possibly illustrate this?
It stated that 'people 40 years older tend to have more worries than younger individuals'. Why choosing 40 years? How would it look with 30 or 50 years of age? It is definitely interesting to know the proportion of concerns and acceptance across the different age groups. A simple figure could probably illustrate this. May higher age per se give more concerns due to less knowledge? In all the panels of Figure 10, knowledge an age are presented as separate values. It should be clarified whether these two are correlated.
I think that the discussion in 384+ that the value is much smaller in the case of public than several other use cases seems to drag the data a little bit too far. Why should we bear this in mind for future drone services?
DISCUSSION.
I find the Discussion to be mostly descriptive with stating most of the facts that are presented in Results. The authors focus on statistically significant differences, but none of these differences are very large. Actually, for real cases they be possibly rather minor. I find little content discussing the real-life impact of such small differences. The data could enable a really interesting discussion of what impact such "statistical" findings should have for future drones. I am not convinced that any of the 'significant differences' will influence, obstruct or exclude the introduction of drone services for valuable use-cases. Accordingly, I ask the question why we should introduce large "educational processes" for increasing acceptance of drones? In a scientific dimension I really don’t know, but personally I see no point in spending large resources on the topic. Or maybe we actually have to do that? Not many papers discuss this.
Another example. As the authors state, 'although there was a significant change in attitude in the overall sample', the difference is marginal as I see it (line 211 in the paper; d = .12, 'which is a weak effect' according to the authors).
It has previously been well described that acceptance of drones are higher for public services as disaster management and emergency services. This seems to be valid also in this study and even across the different countries. It seems a little bit unnecessary to state that countries have significant differences regarding general attitudes to drones as the country seems to play a minimal role in predicting the acceptance.
The statement 'Most people already have some experience with drones, albeit mostly second-hand expertise (63%), meaning having seen or heard drones. 19% of 182 the respondents have used a drone independently and have first-hand experience. Only 183 18% stated they have no experience with drones.' Again, I point to a variable which is not exact and with questionable strength.
CONCLUSION.
I would recommend that Conclusion section starts with the lines 513 - 516. This states firmly the major importance of the paper; knowledge about drones seems to be the most important factor influencing public acceptance. This is also mentioned several times in the discussion. Another important statement in Conclusion is that drones for public services seems to have the highest acceptance compare to 'business/profit' services.
A large part of the current Conclusion is actually more appropriate in the Discussion. It should either be skipped or moved to the Discussion part.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsDear authors,
Thank you for your prompt and thorough answers to the previous comments. Your resubmitted paper is much more concise and well rounded, in my opinion.
Nevertheless, there are a few minor details that should be fixed before publication.
Apparently, you went a little overboard with your figure captions, concerning the bar charts. For example, for Figure 1 (lines 318 – 320) you doubled the necessary information. My suggestion for the caption of Figure 1 would be the following: “Mean values of attitude toward drones at the beginning and end of the survey for the participating countries and the total sample. Whiskers indicate standard deviation.” This, or a similarly short description, should be used to convey the information; this holds true for the other bar charts as well.
Your caption for Figure 3 runs over into the main text (see line 363).
Your added sentence in line 507 contains a typo.
In line 689, you mention the “Diffusion of Innovation Theory” but omit a/the reference. Please correct that.
Author Response
Dear Reviewer,
Many thanks for reviewing the paper again and for your further recommendations. We are pleased that the quality of the paper has improved from your point of view. Your comments from the first review helped us a lot.
Following your suggestions, we have corrected the individual aspects. We have corrected the typo in line 507, inserted a blank line after the caption of Figure 3, shortened the captions under the bar charts, and added the source concerning the Diffusion of Innovation Theory.
With best regards
Maria Stolz
