PONE-D-24-16202A comprehensive survey and comparative analysis of time series data augmentation in medical wearable computingPLOS ONE

Dear Dr. HASAN,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Friedhelm Schwenker

Academic Editor

PLOS ONE

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2. Thank you for stating the following financial disclosure:

“This study was supported in part by the Deutscher Akademischer Austauschdienst 645

(Award No. 91831212) and within the grant SAM-SMART “Security Assistance 646

Manager for the Smart Home” (Bundesministerium für Bildung und Forschung, Grant 647

No. 16KISA074)”

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our peers send their comments to your manuscript. They find it interesting and suggested possible ways to improve the paper. Please take them into account when you prepare the revision.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: 1. The topic is interesting, however for a full-fledge survey paper I would say the coverage is not sufficient. This is rather an experimental study as they have done several experimentation to understand the impact of data augmentation.

2. The challenges in the said field should be discussed elaborately. Also discuss the motivations behind the work, shading some lights on the data augmentation aspect as one of the research challenges.

3. In the research gap section, can they be more specific on the gaps that previous surveys did not address/cover?

4. Section 2.1: They should discuss more clearly the reasons for proposing such taxonomy.

5. Can they write the captions for Figs. 2-3 in a more descriptive way to understand the differences among different data augmentation methods?

6. I suggest the authors to use more datasets.

7. I suggest the authors to use different GAN models.

8. They need to improve Section 5 significantly to understand the impact of the data augmentation issues.

9. As they are considering this as a survey paper, they need to discuss the limitations and future research avenues more strongly.

10. There are some typographical and grammatical errors. Please reread the paper and correct those.

Reviewer #2: The paper surveys data augmentation techniques for univariate and multivariate time series classification in the context of medical applications. The authors provide a comprehensive overview about data augmentation methods for such time series.

The study reports experimental results in form of mean values of 5 runs for each setup. The TSDA methods are applied to the Deap, Opportunity, Biovid and PainMonit data sets with a single learning algorithm for each dataset. However, the metrics and parameters being used are not consistent, which makes comparisons difficult. Maybe it could be helpful to provide results for all augmentation factors for all experiments (e.g. 0.2, 0.4, 0.6, 0.8 for "Opportunity" and 3-10 for the others) and F1-scores for all datasets. Moreover, it is insufficient to report mean values only, instead an appropriate measure of dispersion should be considered as well (maybe other than variance, due to the small number of samples). Something like a Critical Difference Diagram would be helpful in judging the results of the experiments (Friedman test and post-hoc Nemenyi). Simple classifiers for a baseline comparison could be helpful (something like multivariate dynamic time warping classifiers). Finally, it would be interesting to get more information about the connection between dataset characteristics and DA methods. As an example: "Rotation" impairs performance on BVDB, PMDB and Opportunity but improves performance for emotion recognition. How does this relate to the characteristics of DEAP and what general conclusion may be drawn from this?

Unfortunately, this reviewer was unable to verify the results based on the provided implementation with manageable effort (e.g. mismatching dimensions for Opportunity data).

Additional remarks:

Equations should be embedded into sentences (e.g. equation (1)).

Matrices (e.g. equation (2)) could be typeset using \vdots, \ddots, etc..

There is a typo in equation (14).

The naming of the variable "macro F_1 score" could be reconsidered. Using words in equations could be avoided.

There seems to be a mistake in the first sentence of Section 3.2.

The colors in Fig. 8 are unnecessary and might be misleading.

The y-axis in Fig. 8 could be limited to a smaller range (e.g. 50 to 90) in order to make the results more recognisable.

The notation in equation (10) and (11) could be improved.

Something seems to be missing in the second sentence of Section 6.

It could be helpful to make a difference in notation of matrices and vectors and scalars.

The parameters that appear in Table 3 are not sufficiently documented. For example \Omega is introduced as a random matrix in the context of Jittering (equation (3)). In table 3, however, it seems that \Omega denotes variance in the context of scaling. As an example, it might be more instructive to write something like $\alpha \sim \mathcal{N}(0.1,1)$ in row 3 of table 3.

The meaning of \mathbb{R}^{+*} in Section 3.4 (line 460) is unclear.

The axis labels and legends in almost all figures are not readable in a print version (Figs. 2,3,4,5,7,8,9,10,11).

The formal descriptions of DA methods in section 2 should be reconsidered. E.g.:

- It is unclear in how far equation (3) describes a rotation. The components of R hold random values between -1 and 1. The Hadamard product of this matrix and a data matrix X doesn't seem to realize a rotation.

- What is the meaning of \mathsf{T} in the exponent in equation (5)? There seems to be no need for transposition.

- equation (9) is inconsistent in notation.

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Reviewer #1: No

Reviewer #2: No

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PONE-D-24-16202R1A comprehensive survey and comparative analysis of time series data augmentation in medical wearable computingPLOS ONE

Dear Dr. HASAN,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please read carefully the comments of the reviewer and prepare your revision taking into account these hints.

Please submit your revised manuscript by Nov 28 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Friedhelm Schwenker

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: This submission is an improvement over the previous one (especially Section 3). The authors have replied to all previous comments.

Parts of the statistical analysis are unclear (to me). For example: Is Figure 8 reporting on pair-wise significance tests? This would be unusual (probability for random validation grows with number of methods, see for example [Janez Demsar, 2006]).

There are still some minor issues in notation, type setting and typography. Notation and type setting are flawed especially regarding the punctuation of equations. Some captions are still not recognisable in a print version (e.g. Fig 11).

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

A comprehensive survey and comparative analysis of time series data augmentation in medical wearable computing

PONE-D-24-16202R2

Dear Dr. Abid,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Friedhelm Schwenker

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

no furhter moments

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: This reviewers comments have been addresed in a detailed fashion. The clarification of the statistical analysis in Figure 8, including the implementation of the Bonferroni correction, addresses the concerns raised effectively. Additionally, the adjustments to notation and figure readability further improve the manuscript.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

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