Comparison of the three European regions
The initial goal of our survey was to explore biomedical professionals' general perceptions of plagiarism in Europe and China, as well as the similarities and contrasts between the two regions . Like others 27,28,29], we focused initially on the similarities and differences of perceptions between the Western World and the Eastern World, and did not address potential disparities within Europe . However, it was also apparent that the responses from European respondents exhibited geographical heterogeneity. Fortunately, the data we had gathered allowed for more in-depth research into perceptions of plagiarism across Europe. The present subsequent analysis provides additional novel empirical evidence about commonalities and disparities in the views held by biomedical researchers with regard to plagiarism.
Here, we did not repeat association analysis between responses and general demographic variables because this was covered in the 2020 article . The purpose of the present analysis was to compare and contrast responses in three European regions: the Nordic countries, southern Europe, and northwestern Europe.
The main findings
Not unexpectedly, the main conclusions of the current analysis are very comparable to what we found in our 2020 article . For example, in general, the perceived harm of plagiarism lies between that caused by data falsification and inappropriate authorship, multiple submission. Furthermore, the existence of intent was deemed more relevant than the part or length of the copied text in identifying a plagiarism act. A similar tendency was also observed in the present study about perceptions of specific practices: most respondents in the three European regions correctly identified the blatant plagiarism practices, but they identified the subtle ones less correctly. Nonetheless, even the most blatant forms of plagiarism, such as appropriation of another's text or image without PROPER attribution, which are clearly classified as plagiarism in many widely accepted guidelines 30,31,32], were never identified by 100% of the respondents.
Nevertheless, the proportions of respondents who did not identify/consider some specific practices as plagiarism varied across the three studied geographical regions within Europe. In other words, the comparison of the three regions reveals some intra-European divergent perspectives on plagiarism, despite showing broadly similar response patterns.
We need to state that we did not claim all of the listed practices in Sect. 2 of our questionnaire constituted plagiarism. By mixing plagiarism and non-plagiarism (undefined according to the current universal guidelines) practices, we wanted to investigate the respondents’ views of these practices. Among those practices, some universally constitute evident plagiarism, such as Copying text from someone else’s publication without crediting the source, and Copying an image from someone else's publication without crediting the source. Other practices might seem less straightforward to some, such as Copying text from someone else's publication with crediting the source, but without quotation marks, and Rephrasing text from someone else's publication without significant modification of the original, but with crediting the source. It is interesting to see how similarly or dissimilarly the respondents from the three European regions viewed these practices.
Summary of the comparison
According to our findings, more agreement was reached for the evident plagiarism practices (i.e. they were identified by over 90% of the respondents), and more divergences existed for the other practices, including the less evident plagiarism practices and those undefined practices.
In summary, compared with the other two European regions, Nordic respondents were more inclined to recognize the listed practices as plagiarism. Compared to the southern respondents, Nordic and northwestern respondents tended more frequently to consider less evident practices as plagiarism, such as Rephrasing another person’s work without crediting the source and With permission from the original author, using another’s text without crediting the source. In contrast, the southern respondents were the most likely to identify recycling of one’s previously rejected research proposal as plagiarism.
Literature on perceptions of plagiarism across Europe
Earlier studies on plagiarism and research misconduct were generally conducted by researchers from English-speaking countries [7, 8, 7,8,33,34,35,36], and cultural factors were primarily focused on Western and Asian countries [34, 37]. Some recent research has begun to focus on intra-European differences, and some distinctions have been identified. The project IPPHEAE, whose conclusions have been documented in scientific articles and reports 37,38,39,40,41,42], is one of the most significant projects.
The IPPHEAE project investigated higher education institutions (including students and staff) in 27 countries across Europe to see how they dealt with plagiarism and academic misconduct. Despite limited response rates in a few nations, the project yielded a wealth of data for cross-sectional comparison, even taking into account potential limitations in terms of representativeness.
When presenting the outcomes of the IPPHEAE project, Glendinning  noted “great variability in understanding what constitutes plagiarism and what was deemed acceptable academic practice” and pointed out that “the lack of consensus over what constitutes plagiarism is perhaps one of the major barriers to academic integrity across the EU.” Years later, in our survey, “the lack of consensus over what constitutes plagiarism” mentioned by the report has been documented again among the European biomedical researchers.
Although IPPHEA is a country-based research project, a general trend (without statistical analysis) is apparent from the IPPHEAE findings: the Nordic respondents (especially those in Finland and Sweden) were more likely to identify the two specific practices [(a) 40% word-for-word copied work with no quotations, (d) 40% copied work, with some words changed with no quotations, references or in text citations.] as plagiarism than their counterparts in northwestern Europe (especially those in France, Germany, and the Netherlands), while the latter were more likely to do so than their counterparts in southern Europe (quantitative data is available from Spain and unavailable from Italy), which was generally consistent with their reported training experience [40, 41, 40,41,43,44,45,46].
A few more studies, in addition to IPPHEAE, also looked into perceptions of plagiarism across Europe, with or without providing detailed data.
Kayaoğlu et al. examined students' perceptions of plagiarism in three countries: Turkey, Germany, and Georgia, and discovered that German students were more sensitive to plagiarism and better at detecting it . The disparity, according to Kayaoğlu et al. , is due to Turkey's "textbook-based" teaching strategy and exam-driven education system, as well as Georgia's similar cultural learning tradition with Asia.
Pupovac et al. studied four European nations and discovered that students in Bulgaria and Croatia were more tolerant of exam cheating than their counterparts in the UK . They also expressed that their findings support Magnus’ conclusion  that tolerance for academic misbehavior was greater in post-communist countries.
Liaw et al. observed no significant correlation between nursing students’ self-confidence and clinical performance . Similarly, the IPPHEAE project discovered that self-confidence was not necessarily favorably correlated with understanding or training of plagiarism [41, 43, 45]. Yaniv et al.  reported a dissociation between confidence and accuracy, whereby people tend to have confidence in consensus, even it is less accurate. As a consequence, it is possible that the respondents who reported to be confident with their research practices had experienced more consensus, regardless of how correct it was, on plagiarism definitions and practices. Besides, education and training experiences on the topic of plagiarism might lead those scientific researchers to assume that they had already developed a good understanding of it. In the present work, it has been observed that the Nordic respondents had lower degree of self-doubt of their research practices than their northwestern counterparts. Nevertheless, no difference was revealed between the other regions. The finding here that researchers’ self-confidence was not always positively associated to their knowledge was consistent with the above studies.
Policy and training on research integrity across Europe
The various policies and training on research integrity across Europe might help us to understand the differences we observed between the three European regions.
Back in the year of 2013, Godecharle et al. observed disagreement across Europe in terms of national research integrity guidelines and research integrity training [51, 52]. In addition to the finding that the Nordic countries and most countries of central and western Europe have national guidelines, they also pointed out that two Nordic countries—Denmark and Norway—have a specific law to address research misconduct . Resnik et al. also detected diversity after investigation into the national research misconduct policies of the TOP 40 research and development funding countries, around half of which were European countries . Nevertheless, the intra-Europe consensus has not significantly improved by time. After examining the national regulatory documents on research integrity of 32 countries of the European Free Trade Association in 2020, Desmond and Dierickx expressed worries that the “core-periphery” model of harmonization has not yet been realized and that the divergences on national guidelines would pose threats to fairness and credibility when addressing research misconduct . By reviewing research integrity training in 11 of the 23 members of the League of European Research Universities (LERU), Abdi et al. also found substantial variation across Europe and that educational resources mainly originated from northern and western Europe .
These limited comparative empirical studies have indicated that the northern (and western) European countries are more advanced in their guidelines and training on research integrity. Though the impact on attitudes and practices remain in doubt , education and training of research integrity are believed to improve an individual’s knowledge of research integrity and misconduct [57, 58]. Influences of guidelines also depend on training and education of research integrity. Accordingly, the Nordic respondents in our survey did show higher sensitivity to plagiarism-related/like practices. Compared to the southern respondents, the northern and northwestern respondents did show a more frequent ability to identify the less obvious plagiarism practices, such as inappropriate rephrasing. These findings further remind us of the necessity to promote harmonized approaches to research integrity policy and training in Europe.
Comparison with China
Although we had already compared the European responses and Chinese responses in our original article , it was also of interest to compare the response patterns of each European region with that found for China.
After statistical analysis corrected for differences indemographic factors, some conclusions about discrepancies between Europe and China could be refined compared to our previous work : for example, compared to the two or three European regions, the Chinese respondents were less likely to identify improper referencing as plagiarism (statement 17b, 17c). On the contrary, compared to the southern European respondents, the Chinese respondents were more likely to identify permitted unattributed text appropriation as plagiarism (statement 20e). Of the three European regions, the Nordic pattern of responses differed the most from the Chinese pattren, with the former being more likely to report a few specific practices as plagiarism (Additional files 5 and 6–1, 6–2, 6–3).
It is worth strssing that, as in our previous article, the main goal of our comparative analysis was to help understand different research behaviors, rather than making value judgements of researchers’ perceptions of plagiarism.
With increasing globalization of scientific communications, as in many other areas nowadays, researchers with different cultures and backgrounds are very likely to face the same assessment criteria of research practices. We suggest that understanding the differences is critical for understanding practical differences and addressing plagiarism more effectively.
There are limitations that we should be aware of when interpreting the findings.
One of the most typical biases in surveys on sensitive topics is response bias, and the respondents of our survey were researchers from leading universities, which can lead to the outcome being an estimation of “a better condition”. Besides, considering the low response rate (5.6%, of the European respondents) of our initial survey (possible reasons have been discussed in the previous study ), we should be aware that those answering the questionnaire might have a better understanding or higher English fluency than the others. In addition, the researchers from leading universities were highly exposed to the international research environment (around 60% of the respondents had more than 6 months’ international research experience), which might result in high homogeneity in terms of their understanding of plagiarism. It is conceivable that more discrepancies would have been observed if “less excellent” universities were included for comparison. Moreover, our sampling strategy led to the results of each region being more reflective of particular countries (and no data from central and eastern European countries), which might limit the study's representativeness. As a result, we should be cautious in extrapolating the findings.
Due to the length of the questionnaire (considering that too long questionnaires might decrease the response rate), some practices could not be described in many details, which might influence the respondents’ responses.
The Turnitin definition of plagiarism  and our previous work [19, 20] were used to design and improve our survey instrument. Although we had it improved by consulting experts and performing a trial survey, we nonetheless acknowledge that the instrument had not been formally validated.
The current study was based on replies gathered in 2018, which was more than three years ago. Given that people's perceptions regarding plagiarism may have shifted, especially in light of the increased public spotlight on research integrity and misconduct, it would be ideal if more up-to-date figures were accessible. To our knowledge, however, there are few prior studies that have sought to quantitatively analyze how biomedical scientists perceive plagiarism and compare responses across European nations, especially with such a large number of replies. As a result, we believe this research does still yield insightful and useful results.
The empirical evidence in the present study has proved exitence of disagreement on what plagiarism is across Europe.
The first step towards harmonization of research integrity standards in Europe might be to reach an agreed and clear definition of research misconduct, including what is plagiarism and what it is not. Effective approaches of research integrity training, including education about plagiarism definitions is also needed.