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Article History

Received: 1 February 2025

Accepted: 6 August 2025

First Online: 22 August 2025

Competing interests

: The authors declare no competing interests.

: This study used secondary data from the Gallup World Poll, conducted annually by Gallup, Inc. from 2005 to 2022 across all sampled countries. Gallup obtains ethical approval for its global survey procedures through both internal and external review processes that adhere to internationally recognized research ethics standards, including the Declaration of Helsinki and the ethical guidelines of the Council for International Organizations of Medical Sciences (CIOMS). All data collection is conducted in accordance with applicable national regulations for research involving human participants and the ethical principles set forth in the Belmont Report, disseminated by the U.S. National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. The Gallup World Poll is conducted under the oversight of Gallup’s Institutional Review Board (Gallup IRB). The IRB’s framework is based on the principles of respect for persons, beneficence, and justice. Gallup upholds strict protocols to protect respondent confidentiality and anonymity throughout data collection, transfer, storage, and reporting. Gallup’s procedures also comply with the professional ethical codes of the Worldwide Association for Public Opinion Research (WAPOR), the European Society for Opinion and Marketing Research (ESOMAR), the American Association for Public Opinion Research (AAPOR), the Council of American Survey Research Organizations (CASRO), and the American Statistical Association (ASA). Gallup IRB approval number: 33f44049-4067. Date of approval: June 15, 2022. Scope of approval: Global survey data collection across all countries sampled in the Gallup World Poll, 2005-2022. This study involved only secondary analysis of fully anonymized data provided directly by Gallup. The authors had no access to identifiable personal information and no interaction with survey respondents. In accordance with institutional policy and prevailing ethical standards for secondary data analysis of de-identified datasets, the ethics review committee of Kyushu University, Japan confirms that no additional ethical approval was required.

: Oral informed consent was obtained by Gallup, Inc. from all participants prior to data collection, during the years 2005 to 2022, in accordance with Gallup’s standardized global survey protocol. Consent was administered by trained local interviewers, using a uniform script, and conducted in the participant’s native language to accommodate diverse literacy levels and cultural contexts. Participants were clearly informed about the purpose of the survey, their right to decline or withdraw at any time, and the fact that their responses would remain anonymous and confidential. The oral consent process was documented at the time of the interview in line with Gallup’s internal procedures and ethical standards. Gallup’s informed consent procedures align with the ethical principles outlined in the Declaration of Helsinki, the CIOMS guidelines, and the Belmont Report. Participants were assured that their data would be anonymized and used solely for research and policy analysis purposes. The scope of consent included voluntary participation, data use, and dissemination of findings in a de-identified and aggregated form. No personally identifiable information was shared with the authors, and no direct interaction occurred between the researchers and participants.