PONE-D-22-27998Self-selection biases in psychological studies Personality and affective disorders are prevalent among participantsPLOS ONE

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Center of Science and BNS 52/20-P. The second author was supported by the grant UMO2017/26/D/HS6/00258 from the National Center of Science and the fourth author was

partially funded by the grant 2019/35/B/HS6/00682 from National Center of Science. The

online study was supported by Ministry of Science and Higher Education in Poland in the

form of subsidy for the maintenance and development of research potential at The Maria

Grzegorzewska University in 2020."

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AZ was supported by the grant UMO-2017/26/D/HS6/00258 from the National Center of Science.

PKJ was partially funded by the grant 2019/35/B/HS6/00682 from National Center of Science. 

The online study was supported by Ministry of Science and Higher Education in Poland in the form of subsidy for the maintenance and development of research potential at The Maria Grzegorzewska University in 2020.

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Reviewers' comments:

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: N/A

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

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Reviewer #1: This is an interesting manuscript to review as it highlights that there are significant ways in which research studies are distinct from one another, and these differences have the potential to affect the allure of various studies to various individuals.

The authors try to point out that it is unclear as to the potential personality and affective disorders that may be associated with such choices because people choose the types of psychological studies in which they are willing to participate based on their needs and individual characteristics. This creates an unintentional self-selection bias, but it is important to note that this bias exists regardless.

Most importantly, people who took part in sponsored studies exhibited a greater number of symptoms associated with personality disorders than those who had never before participated for any kind of research.This is a very interesting finding and should prompt researchers to either the alteration of recruiting tactics or much greater caution when generalizing results for this methodological reason.

Reviewer #2: This study presents an interesting concept with a good research question and interesting implications for current research being done in the field of psychiatry. Comorbid personality disorder symptoms can make mood disorders difficult to treat, with patients less likely to respond to medications, more likely to face socioeconomic challenges, likely to suffer from mood symptoms for longer periods of time and hence less likely to comply with their medications. With the most recent research regarding newer antidepressants showing a decline in response to medications and increase in placebo response, this study provides another hypothesis that the patients who are volunteering for these studies may be suffering from additional personality disorder symptoms, which often makes it harder to treat depression.

Overall, I found that the study utilized a good method, and the study design appears clear and easy to replicate. The data analysis appears well done, and there does not appear to be any bias or error.

The authors can potentially identify actionable points in the conclusion section that institutions and other health care providers can utilize in their own research in order to address challenges posed by these findings.

Reviewer #3: It was an interesting concept and would be helpful to know more about such kind of biases that might affect volunteers as a whole. It was helpful to have your excellent statistical analysis. The timing especially with comparing non-Covid times to Covid times especially for a volunteer psychology projects seems like it would have added additional confounding factors to the outcome as you have pointed out. It would be interesting to repeat such a study at the same time and with fewer variables being measured.

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Reviewer #1: No

Reviewer #2: Yes: Lakshit Jain MD

Reviewer #3: No

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Self-selection biases in psychological studies Personality and affective disorders are prevalent among participants

PONE-D-22-27998R1

Dear Dr. Kaźmierczak,

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.

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Kind regards,

Ankit Jain, M.D.

Academic Editor

PLOS ONE

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