PONE-D-24-31956""New Insights into Attitudes Toward Euthanasia: Confirmatory Factor Analysis of the Revised ATE-ES-R Tool".PLOS ONE

Dear Dr. Onieva-Zafra,

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PLOS ONE

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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: Partly

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

Reviewer #1: No

Reviewer #2: No

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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: No

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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: Dear Author:

Thank you for allowing me to review this manuscript. I think it discusses an important topic. I am going to make some comments with the aim of improving this manuscript.

Introduction

Introduction: You make a very correct introduction to the topic, adequately stating the importance and relevance of the topic (Euthanasia). However, I believe that the relevance of this study is not adequately explained. It does not explain why it is necessary to re-evaluate the Attitude Toward Euthanasia scale (ATE ), validated by Fernandez et al, of which some of you are also authors. It should be reflected what possible shortcomings the first version has that obliges to re-evaluate the instrument and what this manuscript contributes again (the values provided with respect to the psychometric properties evaluated in the first version are not bad). In fact, the objective that appears at the end of the introduction does not coincide with the one that appears at the beginning of the discussion.

In the introduction, in the sentence: ‘The number of patients who request or receive MAID is gradually increasing in Spain, since the law was develop a few years ago,’ the meaning of the acronym MAID should be explained and serious references should be made to the law alluded to.

Methodology.

Some methodological aspects require clarification.

-Study population. The study population should be better defined, as the term health worker is very broad, e.g. physiotherapists or psychologists participated? The total percentages of the professions to which they belonged are not provided in the results. This is important, because there may be differences between professions.

-Should justify with references the estimated sample size, which I agree is sufficient for a CFA, but if it is 10 subjects per item it does not correspond to the estimated size. The sample size for factor analysis is a highly controversial issue that I will not develop here (the concept of 10 subjects per item is nowadays very outdated, as the sample size will depend on the number of items, number of response ranges and other elements).

-Information should be provided on the control mechanisms implemented to ensure the internal validity of the results, as this is an online survey. To which e-mail address was the invitation sent to potential participants? Also in the case of recruits, the response rate should be indicated.

One aspect that is not sufficiently explained is whether a new translation of the original English instrument has been carried out or whether it has been based on the version by Fernandez et al. It is also not clear how many translators were involved in each phase of translation and back-translation.

-Aspects of the pilot test should be explained in more depth (what population was used, characteristics, how these people evaluated the instrument).

-The measurements should better explain how each variable was measured, as well as what questions were asked of the participants regarding their knowledge and ethics of euthanasia.

When you describe the instrument you refer to the original four-dimensional structure, but you do not refer to whether this structure is from the original version or the Spanish version of Fernandez et al. This is very much related to the factor analysis.

-I have some important questions on the statistical analysis. To begin with, you do a CFA based on several models. It is essential to explain and reference on the basis of which literature, previous studies or assumptions you test these models, as Fernandez et al. did. Usually the CFA is done on the basis of an EFA, which is then tested on a different sample than the one on which the EFA was performed. If a CFA is done on the basis of an established model(s), this needs to be explained.

-Secondly, the sample adequacy of the factor analysis should be reported (e.g. by reporting the KMO and Barlett's statistic). The type of matrix used (polychoric or pearson) should be reported, determining the approach to the factor analysis that has been carried out (linear or non-linear). This decision is usually made by assessing, among other things, the symmetry and kurtosis of the items (mardia test). The estimation procedure of the model solution (e.g. Unweigthed Least Squares, ULS) or the type of rotation is not shown either. All these aspects should appear in the method. I personally cannot conceive of presenting values without confidence intervals, but I leave this to the editor and other reviewers to assess.

-The reliability analysis should be significantly improved. To begin with, you should provide the omega coefficient, which has many advantages over the Crombach coefficient (both are usually provided). In addition, given that there are models with several dimensions, the reliability values for each dimension should be reported for each model (there are authors who argue that it makes no sense to report a total coefficient in these cases). I am flexible and I do not mind if a total coefficient is reported if there are dimensions in the instrument, but the coefficients of each dimension should always be reported.

-An analysis by known groups could have been carried out. It would improve the manuscript quite a bit, but I understand this is optional.

Results:

In my opinion in the methodology it should appear how it has been done and in the results the data obtained. In the results it should therefore appear the linguistic changes made as well as the results of the pilot test.

The response rate and the number of non-responders should be presented (I agree that the reasons cannot be given for ethical reasons). It is important to know what is the percentage of non-respondents, as non-probability convenience sampling has been carried out and this may affect the accuracy of the results (it should appear in the discussion as a limitation).

-In the CFA, they should report KMO and barlett. My proposal is to present a table showing the fit values of the four models, so that they can be compared. Moreover, in some models we do not have information about the fit values in a complete way (example: CFI in model 1, SRMR of the four models, etc.).

-Present the above-mentioned regarding the reliability-internal consistency values.

-The presentation of the tables should be improved, where values with decimals appear with commas and should be replaced by dots. In addition, the clarity of the graphs should be improved.

-They present a validation where few psychometric properties are evaluated (construct validity and reliability -internal consistency). This is a very important limitation that should at least be admitted in the discussion.

This manuscript requires important changes, but they can be implemented. I encourage the authors to do so. Best regards

Reviewer #2: Dear Authors,

Thank you for allowing me to review this manuscript. It addresses an important topic, and I appreciate the opportunity to contribute suggestions for its improvement.

I will comment by sections-concepts below:

Background

The background section adequately establishes the importance and relevance of the topic (Euthanasia). However, the study's specific relevance is not sufficiently explained. It is unclear why a re-evaluation of the Attitude Toward Euthanasia (ATE) scale, previously validated by Fernandez et al, is necessary. The manuscript should highlight any potential shortcomings of the original version and clearly state what new contributions this re-evaluation provides, especially considering that the psychometric properties evaluated in the first version are not poor.

Additionally, in the sentence, “The number of patients who request or receive MAID is gradually increasing in Spain, since the law was developed a few years ago,” the acronym MAID should be defined, and proper references to the relevant law should be included.

Finally, Furthermore, there is an inconsistency between the objective stated at the end of the introduction and the one that appears at the beginning of the discussion “The main objective of the present study was to validate the questionnaire in Spanish after modifying all the items, changing the expression “the physician” in each item to “the health care team” …

And, you have stated at the objectives: “Therefore, the aim of this study has been to revise the first translation/validation of the Attitude Toward Euthanasia scale (ATE) by Fernandez et al. (29) with a larger sample of participants, to identify the different dimensions of the questionnaire, to partially modify some of the items to adapt them to the current context of our culture and finally to present an instrument with a good reliability and validity”. These objectives need more accurate elaboration regarding: in what population to be applied: nurses, all health care professionals…? And, at the end of the sentence “finally to present an instrument with a good reliability and validity” there is a “value judgment” as you don’t know if this is like that before the study. So, it must be re-phrased.

Methodology

Several methodological aspects need clarification:

- Study Population/sample: The study population and sample (and sample size calculation) must be separated and should be better defined.

Population is supposed to include all health professionals at Balearic health service but must to define what type of health professionals (and also, state that health professionals and health workers comprise the same population). The results section should include the total percentages of the different professions involved, as there may be significant differences between them. The inclusion of Nursing students must be clarified. Why not other health students but yes to a resident (specialist professionals in training programs)? Were all resident (from different professions included)?

- Sample Size Justification: The estimated sample size should be justified with references. Although the sample size appears sufficient for a Confirmatory Factor Analysis (CFA), the rationale that it is 10 subjects per item does not align with the estimated size. The sample size for factor analysis is a highly debated issue, and the outdated concept of 10 subjects per item should be reconsidered. Modern approaches consider the number of items, response ranges, and other factors.

Additionally, some of the data provided in that section are results and could be placed at the results section.

- Inclusion/exclusion criteria: You have mentioned “The inclusion criteria were: to be an active health professional in any of the Balearic Islands health system management offices, to be a nursing degree student or a health professional in specialist training in the Balearic Islands, to understand the language and concepts used in the instrument, and to agree to participate in the study by completing the informed consent form authorizing the use of the information for scientific purposes. The exclusion criteria included health workers who declined participation”. From my point of view are not correct. How do you Check if a participant understands the language and concepts of the instrument, if the questionnaire was sent by e-mail? (only after reading the text, you can realise that this is checked by a number of questions included on sociodemographic section of the questionnaire). This point needs clarification. In addition, inclusion and exclusion criteria are characteristics who have the participants and allow them to participate or not. Agreeing or declining participation are not characteristics, are decisions and a part of recruiting.

- Control Mechanisms for Internal Validity: The manuscript should describe the control mechanisms implemented to ensure the internal validity of the results, particularly given that this was a mailing survey. Information on how the survey invitations were distributed (e.g., to which email addresses) and the response rates among different recruitment methods should be included. How were the inclusion criteria addressed and evaluated?

Design

From my point of view the design is incomplete. Is not the usual manner of present the type of research design. Was a cross-sectional survey with only one collection point? Was the design performed including different phases, as usual in this type of studies for validation? For instance: a translation-back translation stage, pilot phase, psychometric validation, etc…

- Translation Process: I understand that you had conducted a new translation and cultural adaptation of the original English instrument, but a Spanish version exist (Fernandez et al. version). So, we need more information about it, why and how was performed, more than your explanation. Also, details on the number of translators involved in each phase of translation and back-translation should be provided.

- Pilot Test Details: The manuscript should elaborate on the pilot test, including the population used, their characteristics, and how these individuals evaluated the instrument. Again, write methods on the section methods and results on results section, don’t mix it.

- Measurement Explanation: The manuscript should better explain how each variable was measured, including the specific questions asked about participants’ knowledge and ethics regarding euthanasia.

- Instrument Structure: When describing the instrument, you refer to a four-dimensional structure, That I’m assuming is the English original structure but it is unclear whether this structure pertains to the original or the Spanish version by Fernandez et al. This is closely related to the factor analysis and should be clarified.

- Statistical Analysis: Several important aspects of the statistical analysis need attention:

- The CFA is based on several models, but it is essential to explain and reference the literature, previous studies, or assumptions that justify testing these models, like what Fernandez et al. did. Typically, a CFA is conducted following an Exploratory Factor Analysis (EFA), which is then tested on a different sample or if the CFA is based on pre-established models (hypothesis contrasts), this should be clearly explained. If not, it seems that you are exploring different options to see what of them is better fitted, but this is not correct, then, explain why you decided to do a 4 CFA based on different dimensions?

- Report the sample adequacy measures for factor analysis, such as the Kaiser-Meyer-Olkin (KMO) statistic and Bartlett's test of sphericity. Additionally, indicate the type of correlation matrix used (e.g., polychoric or Pearson) and specify the approach to factor analysis (linear or non-linear), which is often determined by assessing item symmetry and kurtosis (e.g., Mardia's test). The estimation procedure of the model solution (e.g., Unweighted Least Squares, ULS) and the type of rotation should also be specified.

- The reliability analysis requires improvement. The manuscript should include the omega coefficient, which is often preferred over Cronbach’s alpha. For instruments with multiple dimensions, reliability values for each dimension should be reported for each model. While some argue that reporting a total coefficient is unnecessary when dimensions exist, I am flexible on this point, but coefficients for each dimension should always be reported.

- Consider conducting an analysis by known groups to enhance the manuscript, although this is optional.

Results

As I said, the methodology should detail the procedures, while the results should present the data obtained. Therefore, the results should include the linguistic changes made and the outcomes of the pilot test.

- Response Rate: Include the response rate and the number of non-respondents. Even though reasons for non-response cannot be detailed for ethical reasons, the percentage of non-respondents is crucial information. This is particularly important given the non-probability convenience sampling used, which may impact the results’ accuracy and should be discussed as a limitation.

- Sociodemographic results: Reading your manuscript is not clear if you are studying all health professionals or only nursing professionals, because too many times refer to nursing specifically. This must be cleared on the text and on the tables-figures. Data on frequencies of different group of professionals is crucial to understand the sample studied and the implications on the results.

If “70.2% of the professionals recognize that they have little or no knowledge of the law on the regulation of euthanasia, while 29% have a broad knowledge of it”, then this is contradictory with your inclusion-exclusion criteria that I’ve mentioned before and needs clarification. The same for Health care ethics training.

- CFA Reporting: Include KMO and Bartlett's test results in the CFA, this is important to know about the adequacy of the sample. I recommend presenting a table comparing the fit values of the four models. Currently, some models lack complete information on fit values (e.g., CFI for Model 1, SRMR for all models). In addition, your interpretation and analysis of the data obtained could be subjective and influenced by a tendency to a specific model. For instance: “For these indices, lower values indicate a better fit, with a reference value of 0.08” (referring to a SMRS and RMSA), Why 0.08 and no other? What is the literature who avail that number? The literature says that the closer to Zero the better fit. Nevertheless, data in RMSR is lacking. And, you have to results recommending 1 dimension structure who is in accordance with the theory (first CFA and parallel analysis), then one option is to analyze the data with other perspective, for instance, RASCH analysis and evaluate if the data fits into that model for a 1 dimension.

- Reliability Reporting: Present the reliability values as discussed, including values for internal consistency.

- Tables and Graphs: Improve the presentation of tables, ensuring that values with decimals use periods instead of commas. Additionally, the clarity of graphs should be enhanced.

- Psychometric Properties: The validation presented evaluates limited psychometric properties (construct validity and internal consistency reliability). This is a significant limitation that should be acknowledged in the discussion. The comments added here could improve this issue and to have a more complete psychometric validation study.

Discussion and conclusions

These sections are totally influenced by the results, so I don’t have any additional commentary on that, because you must to re-write according with the amendments on the other parts of the manuscript.

Finally, likely you must improve the grammar and the language. For instance, “Mother tongue” could be used but is a “literal” translation, likely “Mother language” or “native language” is better. This is only an example, but there are more sentences that need better redaction.

As my conclusion, this manuscript requires significant revisions, but they are feasible. I encourage the authors to address these suggestions. Re-think on the title of the manuscript, if taken into account my recommendations and something like “Re-evaluation of psychometric properties of … based on…” could be feasible.

Best regards.

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Reviewer #1: Yes: Héctor González-de la Torre

Reviewer #2: Yes: José Verdú-Soriano

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PONE-D-24-31956R1"Re-evaluation of the Psychometric Properties of ATE following Changes in Euthanasia Regulations in Spain".PLOS ONE

Dear Dr. Onieva-Zafra,

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 submit your revised manuscript by Jan 24 2025 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,

Cord M. Brundage, D.V.M., Ph.D.

Academic Editor

PLOS ONE

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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 #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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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 #1: Partly

Reviewer #2: Yes

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

Reviewer #1: No

Reviewer #2: No

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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 #1: Yes

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 #1: Yes

Reviewer #2: Yes

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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 #1: Dear Authors

Thank you for your efforts. I believe that the changes implemented have improved the manuscript significantly. You have responded adequately to most of the recommendations and for this I congratulate you. However, given that you have made substantial modifications to the analyses performed, in my opinion there are still some new questions to be answered. Please find attached my recommendations for improvement:

Modify this expression: The original scale had a Cronbach's Alpha of 0.87.page 25: It is better to express it like this: A Cronbach's Alpha of 0.87 was reported.

Indicate in this sentence that the numbers in brackets are the item numbers: example: severe pain [items 1,3,9],

-I think you have confused face validity with content validity. Face validity assesses the comprehensibility, appropriateness and acceptability of the tool from the point of view of the population where it is to be used. The use of experts is generally used to assess content validity. I will be flexible in this respect, as for this instrument the study population and experts are similar, but I note this for future research (ideally you would have used non-expert healthcare for face validity).

-You state in your answer that you have divided the sample to perform the EFA and then the CFA. But the system you used to divide the sample does not appear in the manuscript (you usually use systems that ensure the homogeneity of the two sub-samples: e.g. the SOLOMON system of Lorenzo Seva and Ferrando). The system used for this sample division should appear in the text. But more importantly, the results do not show how many subjects were included in the EFA and how many in the CFA. In fact, the KMO of the sample in the CFA does not appear either. Furthermore, the models tested in the CFA should be justified with references. It is accepted that your EFA indicates two dimensions and therefore this model is tested, but the one-, three- and four-factor models are not justified or referenced.

-In table 4 in the table footer you should put the meaning of each index for a better understanding.

-You have used a RASCH approach, for which I congratulate you, as it is a methodology that few researchers have mastered. However, there are aspects that raise doubts in my mind:

-The RASCH methodology starts from one premise and that is the unidimensionality of the model and the items. Therefore it is justified to perform a rasch for the one-dimensional model, but I do not understand how to perform a rasch for the two-dimensional model, as this goes against a basic assumption of the rasch. There are some recent articles that defend the combination of factor analysis and rasch, but always based on the performance of unidimensionality analysis, which in your case I do not appreciate. This is very important and is not clarified or explained in your manuscript. If you cannot explain it, my opinion is that it is better just to present the rasch for the one-dimensional model. Additionally you should support with references the fit values of the infit-outfit.

-Another basic assumption of the RASCH is the local independence of the items. This is usually checked with Yen's Q3 test, the correlation matrix of the residuals being provided as evidence for this independence. Therefore, please perform this test and indicate the threshold values set for it.

The manuscript has improved, but these issues need to be resolved. Best regards.

Reviewer #2: Dear Authors,

Thank you very much for taking into account all the comments made by this reviewer. The new version of your manuscript partially reflect our comments and answers but some of them remains lacking.

I'm sure that the manuscript will improve and finally will be published but must to be well prepared in that way.

- Thanks for improving the introduction section and objectives ads mentioned.

- My main concern is based on methods and their reflection on results. You have made an effort to fulfill our recommendations but some of them are not reflected on the text, at least as you answered on the responses to reviewers, for instance:

1. You have mentioned that the sample was divided into 2 samples, one for the EFA and other for the CFA, but this remain unwritten on the manuscript and is relevant to know by the readers. You must to provide information on how the sample was divided (Salomon's methods,...) and the sample size of each subsample. And also, there are incongruences on those data, as you have mentioned on the parallel analysis that all the sample was used for that (and the parallel analysis is a part of the EFA analysis). In other words, you can use 2 methods for decide the number of factors at the EFA, the Eigenvalues or parallel analysis, but both are based in the same sample, and on the text is not clear.

2. Regarding the above mentioned, I feel that the different subsections on the text must to be in other order or combined. As I mentioned, Parallel analysis is a method to decide how many factor retain at EFA, so it must to be at the same section of EFA analysis and mention that you have made both approaches, based on Eigenvalues and parallel analysis to decide how many factors and models you will try to confirm.

3. Yo say that an analysis of asymmetry and kurtosis, also a Mardia's test was performed to decided what type of correlation matrix to use, but there is a lack of data information to know if a Pearson's Matrix fits the data. In that way, we must to assume that the data are correct. Did you test a polycoric matrix?

4. Some of the figures or tables are not where the text appear the title.

5. Thank for taking into account my comment about other types of analysis like RASCH, but if you provide, please, make it with all the information. Provide information about the Rasch model used for polytomous items like this instrument. And provide data that the RASCH analysis could be performed. You must to assure two premises: unidimensionality and local independence of items. for the second, usually, a Q3 Yen's indices must to be provided. If there is a high correlation between residual correlations (up to 0.2-0.3), RASCH analysis could not be ideal, but we don't have information about those data. Could you provide a figure of Wright graph and a typical true score - theta distribution sigmoid curve?

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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 #1: Yes: Héctor González-de la Torre

Reviewer #2: Yes: JOsé Verdú-Soriano

**********

[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.

PONE-D-24-31956R2"Re-evaluation of the Psychometric Properties of ATE following Changes in Euthanasia Regulations in Spain".PLOS ONE

Dear Dr. Onieva-Zafra,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but still 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 note that after several rounds of reviews and revisions there are still some questions from the reviewers on the analysis and dividing of samples as they are described in your manuscript. Please be as clear and transparent as possible both in your responses to the reviewers AND in the changes that you make in response to their concerns. If these valid concerns remain unaddressed in the manuscript it is possible that this manuscript will not be accepted.

Please submit your revised manuscript by Feb 22 2025 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 in addressing the reviewers' points. 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,

Cord M. Brundage, D.V.M., Ph.D.

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.

Additional Editor Comments:

I have underlined specific comments from the reviewers indicating that changes need to be reflected in the manuscript not just the response to reviewers. These are reasonable and justified requests.

[Note: HTML markup is below. Please do not edit.]

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 #1: (No Response)

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 #1: Partly

Reviewer #2: Yes

**********

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

Reviewer #1: No

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 #1: No

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 #1: Yes

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 #1: Dear authors:

Thank you for the work done and the changes implemented. I would like to ask you some questions that I have doubts about:

- You indicate the use of the SOLOMON system to divide the sample. Please indicate how it was carried out (statistical programme used) and the Ratio Communality Index obtained.

- Since you used the mardia test to ensure the convenience of using a pearson matrix, provide the values of symmetry and kurtosis of the items.

- Indicate that you confirmed the unidimensionality from the EFA, but in this the analysis identified two factors: ‘Regarding the total explained variance, the analysis identified two factors that together account for 64.51% of the total variance of the construct studied. The first factor explains 52.07% of the variance, while the second factor accounts for 12.43%’. There are other types of analyses to assess the unidimensionality of an instrument. Include objective indices that justify the unidimensionality of the model and therefore the convenience of carrying out a Rach analysis.

Reviewer #2: Dear Authors, I hope that you have enjoyed the Christmas holidays and wish you a Happy 2025.

I just read the comments and the new version of your manuscript that, for sure, is getting better.

Thanks for taking in consideration all the comments. My intention is to improve your manuscript and, that, finally will be published.

I have minor comments that must to be addressed to be ok for publication:

- First of all, please, take care when made changes and be confident that all if well approached. For instance, on the revised manuscript you have:

"Analysis of Rasch Models: Unidimensional and Two-Factor Approaches.

We conducted a Rasch analysis to evaluate the fit of items within both a unidimensional

model and a two-factor model".

But this is not according with the comments and the new supposed version, as you said that only will provide Rasch analysis for the 1 factor model to analyze unidimensionality. Please, read carefully your manuscript and re-write according with the comments.

- If you said that something is made, please, write what was made at methods section and provide only results at results section. Below, some examples:

- What software was used to implement Solomon method to split the sample in two sub-samples?

- Please state at methods, assuming that the instrument is based in a likert scale, that "RASCH analysis was made under an Andrich's Rating Scale Model for polytomous Items" (reference, for instance: Meyer J.P. Applied Measurement with JMetrik. Routledge: New York, 2014)

- Please, include in methods section all the information about how the RASCH analysis was made. You have written on the results but not how was made at methods. Include a sentence about the analysis to verify "local independence of items", about Wright graph and Characteristic curve, etc,... A numbered list of how was made will be excellent.

- Looking at the results of the RASCH analysis, this is not the best, based on the metrics provided.

Please, as I mentioned before, state at methods section what type of analysis was made: unfit-outfit, difficulty, reliability and separation indexes for both persons and items, Q3 Yen coefficient-index, graphs,... After that present all data on the results section and, finally, discuss the results on Discussion section. I'm realized that nothing is mentioned on discussion about RASCH analysis, indeed, nothing is discussed about the 1 factor model. You have data to mention that "based on the RASCH analysis, the one factor model have a good fit to the model with exception to quality statistics (reliability and separation index) who..."

**********

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 #1: No

Reviewer #2: Yes: JOSÉ VERDÚ-SORIANO

**********

[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.

PONE-D-24-31956R3"Re-evaluation of the Psychometric Properties of ATE following Changes in Euthanasia Regulations in Spain".PLOS ONE

Dear Dr. Onieva-Zafra,

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 submit your revised manuscript by Mar 09 2025 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,

Cord M. Brundage, D.V.M., Ph.D.

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.

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 #1: All comments have been addressed

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 #1: Yes

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: No

**********

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 #1: Yes

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 #1: Yes

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 #1: Dear authors:

Thank you for your efforts throughout the review process. I know it has been hard and required a lot of effort on your part, I hope that at least you have found it useful for future research and that you will take my comments as what they are, an opportunity for improvement. After reading the latest version, I consider that the manuscript can be published, since the comments have been answered and this version is more consistent. I am only going to make a couple of stylistic comments that need to be adjusted. On the other hand, I recommend that in future validations you use the FACTOR program for the factor analysis, not only for the sample splitting procedure, which provides advanced factor analysis, providing for example also confidence intervals for the calculated indices or factor loadings, as well as an analysis of the possible unidimensionality of the model, which can help you to approve other approaches (e.g. Rasch analysis).

Comments:

-In the sentence ‘Two items were reverse coded to check for response bias’ indicate which are the items with reverse scoring (it would be sufficient to provide the item number).

-In the Data analysis section, the reference to the jMetrik software version 4.1.1. should be deleted, as the Rasch analysis has finally been eliminated. The FACTOR program, used to carry out the SOLOMON procedure, should be introduced instead (it is more appropriate to mention the FACTOR program in the method than in the results).

-In table 1 it is better to put the standard deviation in brackets after the mean; M(SD). You should add footnotes explaining these abbreviations.

Finally, I can only congratulate you on your work. Best regards

Reviewer #2: Dear authors,

Thank you very much, again, for your efforts in applying the reviewer’s suggestions and to going better in your manuscript.

The decision on delete/eliminate of the manuscript some analysis made is debatable but understandable. For instance, the decision of not provide data on the RASCH analysis. But I’m accepting this decision based on your answer.

Nevertheless, there are some comments/suggestions that you answer to reviewers, however, not reflected on the manuscript:

- Please, re-write the manuscript and put all the information regarding methods on the manuscript methods: all data and information regarding, for instance, the rationale to test different factors models, Mardia’s test, Solomon procedure, parallel analysis, etc,… must to be written at te methods section and in a convenient order related to the procedure. This recommendation is not new and not addressed on the manuscript.

- Please, when use abbreviations, for instance, on the tables, provide complete names as a foot note on the tables. Some of them are in that way and others not.

For this reviewer, it’s important that you address our recommendations, not only in your answers but in the manuscript.

I hope to receive a final version with those comments to, finally, accept it.

**********

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 #1: Yes: Héctor González-de la Torre

Reviewer #2: Yes: JOSÉ VERDÚ-SORIANO

**********

[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.

"Re-evaluation of the Psychometric Properties of ATE following Changes in Euthanasia Regulations in Spain".

PONE-D-24-31956R4

Dear Dr. Onieva-Zafra,

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.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org.

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,

Cord M. Brundage, D.V.M., Ph.D.

Academic Editor

PLOS ONE