Most journals rely on peer review to ensure that the papers they publish are of a certain quality, but there are concerns that peer review suffers from a number of shortcomings (Grimaldo et al., 2018; Fyfe et al., 2020). These include gender bias, and other less obvious forms of bias, such as more favourable reviews for articles with positive findings, articles by authors from prestigious institutions, or articles by authors from the same country as the reviewer (Haffar et al., 2019; Lee et al., 2013; Resnik and Elmore, 2016).

Analysing the linguistic characteristics of written texts, speeches, and audio-visual materials is well established in the humanities and psychology (Pennebaker, 2017). A recent example of this is the use of machine learning by Garg et al. to track gender and ethnic stereotypes in the United States over the past 100 years (Garg et al., 2018). Similar techniques have been used to analyse scientific articles, with an early study showing that scientific writing is a complex process that is sensitive to formal and informal standards, context-specific canons and subjective factors (Hartley et al., 2003). Later studies found that fraudulent scientific papers seem to be less readable than non-fraudulent papers (Markowitz and Hancock, 2016), and that papers in economics written by women are better written than equivalent papers by men (and that this gap increases during the peer review process; Hengel, 2018). There is clearly scope for these techniques to be used to study other aspects of the research and publishing process.

To date most research on the linguistic characteristics of peer review has focused on comparisons between different types of peer review, and it has been shown that open peer review (in which peer review reports and/or the names of reviewers are made public) leads to longer reports and a more positive emotional tone compared to confidential peer review (Bravo et al., 2019; Bornmann et al., 2012). Similar techniques have been used to explore possible gender bias in the peer review of grant applications, but a consensus has not been reached yet (Marsh et al., 2011; Magua et al., 2017). To date, however, these techniques have not been applied to the peer review process at a large scale, largely because most journals strictly limit access to peer review reports.

Here we report the results of a linguistic analysis of 472,449 peer review reports from the PEERE database (Squazzoni et al., 2017). The reports came from 61 journals published by Elsevier in four broad areas of research: health and medical sciences (22 journals); life sciences (5); physical sciences (30); social sciences and economics (4). For each review we had data on the following: i) the recommendation made by the reviewer (accept [n = 26,387, 5.6%]; minor revisions required [134,858, 28.5%]; major revisions required [161,696, 34.2%]; reject [n = 149,508, 31.7%]); ii) the broad area of research; iii) the type of peer review used by the journal (single-blind [n = 411,727, 87.1%] or double-blind [n = 60,722, 12.9%]); and the gender of the reviewer (75.9% were male; 24.1% were female).

We used various linguistic tools to examine the peer review reports in our sample (see Methods for more details). Linguistic Inquiry and Word Count (LIWC) text-analysis software was used to perform word counts and to return scores of between 0% and 100% for ‘analytical tone’, ‘clout’ and ‘authenticity’ (Pennebaker et al., 2015). Three different approaches were used to perform sentiment analysis: i) LIWC returns a score between 0% and 100% for ‘emotional tone’ (with more positive emotions leading to higher scores); ii) the SentimentR package returns a majority of scores between –1 (negative sentiment) and +1 (positive sentiment), with an extremely low number of results outside that range (0.03% in our sample); iii) the Stanford CoreNLP returns a score between 0 (negative sentiment) to +4 (positive sentiment). We also used LIWC to analyse the reports in terms of five foundations of morality (Graham et al., 2009).

Length of report

For all combinations of area of research, type of peer review and reviewer gender, reports recommending accept were shortest, followed by reports recommending minor revisions, reject, and major revisions (Figure 1). Reports written by reviewers for social sciences and economics journals were significantly longer than those written by reviewers for medical journals; men also tended to write longer reports than women; however, the type of peer review (i.e., single- vs. double-blind) did not have any influence on the length of reports (see Table 2 in Supplementary file 1).

Figure 1

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Analytical tone, clout and authenticity

LIWC returned high scores (typically between 85.0 and 91.0) for analytical tone, and low scores (typically between 18.0 and 25.0) for authenticity, for the peer review reports in our sample (Figure 2A,C; Figure 2—figure supplement 1A,C). High authenticity of a text is defined as the use of more personal words (I-words), present tense words, and relativity words, and fewer non-personal words and modal words (Pennebaker et al., 2015). Low authenticity and high analytical tone are characteristic of texts describing medical research (Karačić et al., 2019; Glonti et al., 2017). There was some variation with reviewer recommendation in the scores returned for clout, with accept having the highest scores for clout, followed by minor revisions, major revisions and reject (Figure 2B; Figure 2—figure supplement 1B).

Figure 2 with 1 supplement see all

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When reviewers recommended major revisions, the text of the report was more analytical. The analytical tone was higher when reviewers were women and for single-blind peer review, but we did not find any effect of the area of research (see Table 4 in Supplementary file 2).

Clout levels varied with area of research, with the highest levels in social sciences and economics journals (see Table 7 in Supplementary file 3). When reviewers recommended rejection, the text showed low levels of clout, as it did when reviewers were men and when the journal useded single-blind peer review (see Table 7 in Supplementary file 3).

The text of reports in social sciences and economics journals had the highest levels of authenticity. Authenticity was prevalent also when reviewers recommended rejection. There was no significant variation in terms of authenticity per reviewer gender or type of peer review (see Table 10 in Supplementary file 4).

Sentiment analysis

The three approaches were used to perform sentiment analysis on our sample – LIWC, SentimentR and the Stanford CoreNLP – produced similar results. Reports recommending accept had the highest scores, indicating higher sentiment, followed by reports recommending minor revisions, major revisions and reject (Figure 3; Figure 3—figure supplement 1). Furthermore, reports for social sciences and economics journals had the highest levels of sentiment, as did reviews written by women. We did not find any association between sentiment and the type of peer review (see Table 13 in Supplementary file 5, Table 16 in Supplementary file 6 and Table 19 in Supplementary file 7).

Figure 3 with 1 supplement see all

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Moral foundations

LIWC was also used to explore the morality of the reports in our sample (Graham et al., 2009). The differences between peer review recommendations were statistically significant. Reports recommending acceptance had the highest scores for general morality, followed by reports recommending minor revisions, major revisions and reject (Figure 4). Regarding the research area, we found a lowest proportion of words related to morality in the social sciences and economics, when reviewers were men, and when single-blind peer review was used (Figure 4).

Figure 4 with 5 supplements see all

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We also explored five foundations of morality – care/harm, fairness/cheating, loyalty/betrayal, authority/subversion, and sanctity/degradation – but no clear patterns emerged (Figure 4—figure supplements 1–5). See the Methods section for more details, and Supplementary file 8 for lists of the ten most common phrases from the LIWC Moral Foundation dictionary. In general, the prevalence of these words was minimal, with average scores lower than 1%. Moreover, these words tended to be part of common phrases and thus did not speak to the moral content of the reviews. This suggests that a combination of qualitative and quantitative methods, including machine learning tools, will be required to explore the moral aspects of peer review.

Our study suggests that the reviewer recommendation has the biggest influence on the linguistic characteristics (and length) of peer review reports, which is consistent with previous, case-based research (Casnici et al., 2017). It is probable that whenever reviewers recommend revision, they write a longer report in order to justify their requests and/or to suggest changes to improve the manuscript (which they do not have to do when they recommend to accept or reject). In our study, in the case of the two more negative recommendations (reject and major revisions), the reports were shorter, and language was less emotional and more analytical. We found that the type of peer review – single-blind or double-blind – had no significant influence on the reports, contrary to previous reports on smaller samples (Bravo et al., 2019; van Rooyen et al., 1999). Likewise, area of research had no significant influence on the reports in the sample, and neither did reviewer gender, which is consistent with a previous smaller study (Bravo et al., 2019). The lack of influence exerted by the area of research, the type of peer review or the reviewer gender on the linguistic characteristics of the reports is a sign of the robustness of peer review.

The results of our study should be considered in the light of certain limitations. Most of the journals were in the health and medical sciences and the physical sciences, and most used single-blind peer review. However, the size, depth and uniqueness of our dataset helped us provide a more comprehensive analysis of peer review reports than previous studies, which were often limited to small samples and incomplete data (van den Besselaar et al., 2018; Sizo et al., 2019; Falk Delgado et al., 2019). Future research would also benefit from baseline data against which results could be compared, although our results match the preliminary results from a study at a single biomedical journal (Glonti et al., 2017), and from knowing more about the referees (such as their status or expertise). Finally, we did not examine the actual content of the manuscripts under review, so we could not determine how reliable reviewers were in their assessments. Combining language analyses of peer review reports with estimates of peer review reliability for the same manuscripts (via inter-reviewer ratings) could provide new insights into the peer review process.

The journal dataset required a data sharing agreement to be established between authors and publishers. A protocol on data sharing entitled 'TD1306 COST Action New frontiers of peer review (PEERE) PEERE policy on data sharing on peer review' was signed by all partners involved in this research on 1 March 2017, as part of a collaborative project funded by the EU Commission. The protocol established rules and practices for data sharing from a sample of scholarly journals, which included a specific data management policy, including data minimization, retention and storage, privacy impact assessment, anonymization, and dissemination. The protocol required that data access and use were restricted to the authors of this manuscript and data aggregation and report were done in such a way to avoid any identification of publishers, journals or individual records involved. The protocol was written to protect the interests of any stakeholder involved, including publishers, journal editors and academic scholars, who could be potentially acted by data sharing, use and release. The full version of the protocol is available on the peere.org website. To request additional information on the dataset and for any claim or objection, please contact the PEERE data controller at info@peere.org.

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Thank you for submitting your article "Meta research: Large-scale language analysis of peer review reports reveals lack of moral bias" to eLife for consideration as a Feature Article. Your article has been reviewed by three peer reviewers, and the evaluation has been overseen by the eLife Features Editor. One of the reviewers was Erin Hengel; the other two reviewers have opted to remain anonymous.

The reviewers have discussed the reviews with one another and the Reviewing Editor has drafted this decision to help you prepare a revised submission.

Summary:

The paper presents an explorative study of the linguistic content of a very large set (roughly 500,000) of peer review reports. To our knowledge, this is the first paper addressing such a large data set on peer review and the potential biases often experienced by scholars of all fields. This is highly valuable to academic research as a whole. However, we do not believe the evidence warrants the authors' conclusion that peer review lacks moral bias (see below), and we suggest that the authors revise their paper to focus exclusively on the LIWC indicators (and conduct further research into moral bias, informed by the comments from referee #2 at the end of this email, with a view to writing a second manuscript for future submission). There are also a number of other issues that need to be addressed in a revised manuscript.

Essential revisions:

1. Reducing the emphasis on moral bias in the present manuscript will involve deleting the last 10 rows of table 1 (and similarly for tables 2, 3 and 4), and making changes to the text. The title also needs to be changed, but Figure 1 does not need to be changed.

2. The authors should analyze the data they have for word length, analytical thinking, clout, authenticity, emotional tone and morality in general in greater detail through regression analyses and/or multilevel models.

Here is what referee #1 said on this topic: I am concerned that the explorative approach misses a lot of underlying information. By comparing means of groups, the in-group variance is overlooked. Some of the observed effects might be large enough to hold some sort of universal "truth", but for other cases, substantial effects might still exist within groups. My suggestion would be to rethink the design into one that allows for multidimensionality. One approach could be regression analysis, which would require a more strict type of test-design though. Another approach could be to build reviewer-profiles based on their characteristics. E.g. reviews with a high degree of clout and negative emotion, and low analytical thinking could be one type. Where is this type found? What characterizes it? Additionally, this would allow the authors to include information about the reviewer, e.g. are they always negative? This might also solve the baseline problem, as this would be a classification issue rather than a measurement issue.

Here is what referee #3 said on this topic: All the analyses are descriptive ANOVAs and the like (bivariate). Given the supposed quality of the data, I'd recommend they explore multilevel models. Then they can fix out differences by fields, journals, etc so we get a more clear sense of what's going on.

3. Please include a fuller description of your dataset and describe how representative/biased the sampling is by field and type of journal.

4. Please provide more information on what the LIWC measures and how it is calculated? It would be especially helpful if you showed several LIWC scores together with sample texts (preferably from your own database) to illustrate how well it analyses text. This can be shown in an appendix. If you can't show text from your own database due to privacy concerns, feel free to show passages from this report. (Alternatively, you could take a few reports from, say, the BMJ which makes referee reports publicly available for published papers.)

5. What are baseline effects? What kind of changes should we expect? E.g. when arguing that the language is cold and analytical, what is this comparable to? I would expect most scientific writing to be mostly in this category, and it should not be a surprise - I hope. It would be very useful for the reader to have some type of comparison.

6. Does the analysis allow for the fact that different subject areas will have different LIWC scores? The largest sample of reports comes from the physical sciences, which use single-blind review the most. Reports from this field are also shorter, slightly more analytic and display less Clout and Authenticity. I think your results are picking up this selection bias instead of representing actual differences between the two review processes.

Please discuss.

7. Please add a section on the limitations of your study. For example, there is no discussion of sample bias and representation really.

Also, LIWC is full of issues and problems (NLP has come a ways since LIWC arrived on the scene): do you use the standardized version of LIWC constructs with high cronbach alphas, or the raw versions with poor cronbach alphas?

Does the analysis distinguish between original research content and other forms of content (eg, editorials, opinion pieces, book reviews etc)?

[We repeat the reviewers’ points here in italic, and include our replies point by point in Roman.]

Essential revisions:

1. Reducing the emphasis on moral bias in the present manuscript will involve deleting the last 10 rows of table 1 (and similarly for tables 2, 3 and 4), and making changes to the text. The title also needs to be changed, but Figure 1 does not need to be changed.

Thank you for your comment. We revised the tables according to the reviewers’ recommendations and created new tables where we present multilevel description of the review reports based on the interaction effects of the reviewer recommendation, journal discipline, journal peer review type and reviewer gender. We created the tables for the five LIWC variables (word count, analytical tone, clout tone, authenticity and emotional tone), and two new additional measures (SentimentR- an R package that has its own dictionaries for the emotional tone of the text, and Stanford CoreNLP-a deep language analysis software, which served as the concurrent validity assessment of the tone variables from the LIWC package). All multilevel relations are now presented in new figures, which are the results of the mixed methods linear regression where we controlled the random effect of the journal, word count (except for LIWC word count) and article type. In light of the new results, and coherently with referee recommendations, we introduced a change in the title and replaced the Figure 1. We now have seven new graphs describing linguistic characteristics of the reviews between groups in the main text and eleven graphs presenting the moral variables in the Supplementary file.

2. The authors should analyze the data they have for word length, analytical thinking, clout, authenticity, emotional tone and morality in general in greater detail through regression analyses and/or multilevel models.

Thank you for your comment. As mentioned above, we performed a new analysis, where we used the mixed methods approach with reviewer recommendation, journal discipline, journal peer review type and reviewer gender as predictors (fixed factors) and different journals, word count and article type as the random factor, which would enable us to control the variations between journals (there were 61 journals in total from which some were more represented than others, and the majority of the articles were original research articles). We found significant interaction of the reviewer recommendation, journal’s field of research, the type of peer review and reviewer’s gender in each variable assessment, but we understand that this significance could be due to the large sample size. So, we presented figures with the within-group relations on standardized scales where we presented the differences between groups.

Here is what referee #1 said on this topic: I am concerned that the explorative approach misses a lot of underlying information. By comparing means of groups, the in-group variance is overlooked. Some of the observed effects might be large enough to hold some sort of universal "truth", but for other cases, substantial effects might still exist within groups. My suggestion would be to rethink the design into one that allows for multidimensionality. One approach could be regression analysis, which would require a stricter type of test-design though. Another approach could be to build reviewer-profiles based on their characteristics. E.g. reviews with a high degree of clout and negative emotion, and low analytical thinking could be one type. Where is this type found? What characterizes it? Additionally, this would allow the authors to include information about the reviewer, e.g. are they always negative? This might also solve the baseline problem, as this would be a classification issue rather than a measurement issue.

Thank you for the comment. Excellent point. We re-performed the analysis accordingly. The mixed methods approach revealed that the majority of effects of the differences in the writing style of the reviews can be attributed to reviewer recommendations, much less to the journal’s field of research, the type of peer review type and reviewer’s gender. We tried to provide an overview of the general writing style in peer reviews by presenting relevant variables in the same graphs so that a reader can have an overview about what peer review characteristics predict different language styles.

Here is what referee #3 said on this topic: All the analyses are descriptive ANOVAs and the like (bivariate). Given the supposed quality of the data, I'd recommend they explore multilevel models. Then they can fix out differences by fields, journals, etc so we get a clearer sense of what's going on.

As explained above, we performed mixed methods approach where these effects were analysed jointly. The current analysis provides an overview of the interaction effects in peer review characteristics and sizes of the differences between them.

3. Please include a fuller description of your dataset and describe how representative/biased the sampling is by field and type of journal.

Thank you, we added this both to the methods and the limitations in the Discussion section.

4. Please provide more information on what the LIWC measures and how it is calculated? It would be especially helpful if you showed several LIWC scores together with sample texts (preferably from your own database) to illustrate how well it analyses text. This can be shown in an appendix. If you can't show text from your own database due to privacy concerns, feel free to show passages from this report. (Alternatively, you could take a few reports from, say, the BMJ which makes referee reports publicly available for published papers.)

LIWC has a dictionary with words associated with different tone, and it counts number of words for each tone type in a certain text. The LIWC output is the percentage of words from a tone category in the text. We now provided the calculation of the different tone variables in the Supplementary file, both for high and low levels of tone. The examples are anonymized.

5. What are baseline effects? What kind of changes should we expect? E.g. when arguing that the language is cold and analytical, what is this comparable to? I would expect most scientific writing to be mostly in this category, and it should not be a surprise - I hope. It would be very useful for the reader to have some type of comparison.

Another good point. The results in our study were similar to an unpublished study that focused on the analysis of the peer review linguistic characteristics, but on a much smaller sample and in only in a single journal (https://peerreviewcongress.org/prc17-0234). However, with the new methodological approach we looked at the relationship of the linguistic characteristics and different aspects of peer review process and found important differences. The analytical tone was indeed predominant in all types of peer review reports, but we found differences in other linguistic characteristics. The new results are presented in the revised manuscript.

6. Does the analysis allow for the fact that different subject areas will have different LIWC scores? The largest sample of reports comes from the physical sciences, which use single-blind review the most. Reports from this field are also shorter, slightly more analytic and display less Clout and Authenticity. I think your results are picking up this selection bias instead of representing actual differences between the two review processes.

Thank you for your comment. The dataset characteristics are now described in the limitations in the Discussion section and we are aware that there is a higher prevalence of journals from Physical sciences, double blind reviews and those which asked for revisions. However, the new analyses now include the interaction of peer review characteristics and so we introduced a better control for this selection bias.

7. Please add a section on the limitations of your study. For example, there is no discussion of sample bias and representation really.

As mentioned previously, we added a limitation section to the revised manuscript.

Also, LIWC is full of issues and problems (NLP has come a ways since LIWC arrived on the scene): do you use the standardized version of LIWC constructs with high cronbach alphas, or the raw versions with poor cronbach alphas?

The LIWC version we used is the standardized version with high Cronbach alphas. This has now been clarified in the Methods section of the revised manuscript. We also analysed the data using Stanford CoreNLP deep learning tool in order to increase internal validity of our approach.

Does the analysis distinguish between original research content and other forms of content (eg, editorials, opinion pieces, book reviews etc)?

There were no book reviews in the dataset. However, we did make the distinction between the original articles and other formats (There was the total of 388,737 original articles and 83,972 of other types or articles of those included in the mixed model analyses), which is now described in the Methods. We used this as the random factor in the mixed model linear regression.

Author details

1. Ivan Buljan

   Ivan Buljan is in the Department of Research in Biomedicine and Health, University of Split School of Medicine, Split, Croatia

   Contribution

   Conceptualization, Data curation, Formal analysis, Investigation, Visualization, Methodology, Writing - original draft, Writing - review and editing

   For correspondence

   ibuljan@mefst.hr

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0002-8719-7277

2. Daniel Garcia-Costa

   Daniel Garcia-Costa is in the Department d'Informàtica, University of Valencia, Burjassot-València, Spain

   Contribution

   Data curation, Software, Formal analysis, Investigation, Visualization, Writing - original draft, Writing - review and editing

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0002-8939-8451

3. Francisco Grimaldo

   Francisco Grimaldo is in the Department d'Informàtica, University of Valencia, Burjassot-València, Spain

   Contribution

   Conceptualization, Data curation, Software, Formal analysis, Funding acquisition, Investigation, Visualization, Methodology, Writing - original draft, Writing - review and editing

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0002-1357-7170

4. Flaminio Squazzoni

   Flaminio Squazzoni is in the Department of Social and Political Sciences, University of Milan, Milan, Italy

   Contribution

   Conceptualization, Resources, Data curation, Supervision, Investigation, Methodology, Writing - original draft, Project administration, Writing - review and editing

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0002-6503-6077

5. Ana Marušić

   Ana Marušić is in the Department of Research in Biomedicine and Health, University of Split School of Medicine, Split, Croatia

   Contribution

   Conceptualization, Resources, Supervision, Funding acquisition, Methodology, Writing - original draft, Project administration

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0001-6272-0917

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