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Source References and the Scientist’s Mind-Map: Harvard vs. Vancouver Style marcus clauss, dennis w. h. mu¨ ller, and daryl codron As a scientist develops, a referencing system (linking results/hypotheses to sources) evolves in the mind. This mind-map is an essential working tool that uses indexing features — such as author names — as reference points. The Harvard style (HS), in which citations in the text are made of names and years of publication and the references are listed in alphabetical order, actively helps to establish this mind-map. In our view, the Vancouver style (VS), in which citations in the text are numbers and the references are listed in order of appearance within the text, does not enhance the formation of a mind-map in a similar way and makes detections of incongruity between the reader’s mind-map and the text more difficult. In an ideal academic world, HS would be used because of these two effects: constant education of and easy quality control by the scientific reader. Although VS reduces printing space and allows easier reading for less academically trained readers, scientific readers may find this style difficult when trying to check and verify sources. For reviewers, who cannot opt not to make such checks, VS is even more tedious. We advocate that journals using VS in print should use HS for the reviewing process; further, in the final printed version, the references should be numbered and listed alphabetically rather than according to the order in which they are cited. Especially for maturing scientists, reading texts with HS referencing is essential. Keywords: reference style, Harvard style, Vancouver style, reference list

introduction Adequate referencing of sources — records, ideas, hypotheses, original observations, data, or syntheses — is an integral part of good scientific

Journal of Scholarly Publishing April 2013 doi: 10.3138/jsp.44.3.005

Source References and the Scientist’s Mind-Map

practice and is important for various reasons. These include the traceability of data and interpretations — in the sense that readers could, in principle, acquire the same sources and thereby test the validity of arguments — and the proper allocation of scientific credit (or, in negative terms, the avoidance of plagiarism). These reasons are directly related to good scientific practice. Other reasons may include a display of the author’s capacities, in the sense that a widespread grasp of the scientific literature may emphasize the author’s eruditeness, or an education of scientific readers, who have to learn about a research field by immersing themselves in the respective literature. Here we want to stress several of these reasons and explain our view why one reference style may be more suitable for these goals than the other.

reference styles Different styles for referencing sources have evolved in different areas of science. Excellent overviews of the historical and technical aspects of referencing are given by a website of the British Medical Association1 and by Neville2 — sources on which we rely here repeatedly without referencing explicitly every time. In general, two groups of referencing styles exist. One is the Harvard style, first used in a publication in 1881,3 also called ‘parenthetical referencing.’ It is common in some form or another in social sciences, many humanities, life and environmental sciences, and health education. The other is the Vancouver style, developed by the US National Library of Medicine and adopted by the International Committee of Medical Journal Editors as part of ‘uniform requirements for manuscripts submitted to biomedical journals.’4 It is also called the ‘numerical style’ and is common in some form or another in medicine and related areas, physical and applied sciences, engineering, and journalism and media sciences. There are many variations and intermediate forms between these two styles, but for the sake of our argument, we will first stick to the dichotomy. Differences between the two styles are summarized in Table 1. For the sake of our argument, we provide a short example of a referenced scientific text written solely for this purpose, displayed in each reference style in Table 2. We will refer to these examples in our subsequent discussion.

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table 1. Major differences between the Harvard and Vancouver reference styles Style element

Harvard style

Vancouver style

Citation in the text

Author(s) name and year of publication in parentheses; multiple sources sorted chronologically

Reference list

Sorted alphabetically by author name; various rules for sorting publications of the same first author (e.g., chronologically)

Unique number assigned to source in parentheses or as superscript; multiple sources indicated by the their respective numbers (without a defined order) Sorted in the order in which they were cited in the text

technical aspects: referencing vs. readability and space constraints One major editorial concern when choosing a reference style is the readability of a text. One of the perceived advantages of the Vancouver style is that the text is not interrupted by names of authors. In the case of the reference example in the first sentence of Table 2, the list of three citations could be a significant impediment to easy reading in the Harvard style, under the assumption that the reader does not want to read the source references. In our own experience and according to many other researchers we spoke to, however, the academically-trained reader becomes used to reading text with Harvard-style references very quickly. Ease of reading should therefore not be a major argument in the choice of reference styles for articles published in scientific journals, which directly address a scientific audience. On the contrary, if an assumed sheer reluctance to read source references is the incentive for choosing a reference style, the more appropriate didactic option may be to choose a style that does not allow the reader to evade reading source references easily. This would be done for the very same reason that we consider proper source referencing indispensable in the first place: to enforce good scientific practice. Another important editorial concern is the arrangement of the reference list. In the Vancouver style, the reference list is not sorted alphabetically but in the order in which they are first cited in the text. One rationale


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table 2. Hypothetical scientific text formatted in Harvard and Vancouver styles Harvard style

Vancouver style

A large number of individual studies have reported the time food is retained in the intestinal tract of animals — the so called ‘passage time’ (Foose 1982; Clauss et al. 2005; Clauss et al. 2010). It has been suggested that this passage time increases with increasing body mass (Illius & Gordon 1992) — i.e., larger animal species should have longer passage times than smaller animal species. Because digestive efficiency is a function of the time available for digestion (Hume 2005; Clauss et al. 2007), it follows that larger animals should be able to achieve higher digestibilities than smaller animals. Surprisingly, empirical evidence does not support this line of reasoning (Justice & Smith 1992; Clauss et al. 2009).

A large number of individual studies have reported the time food is retained in the intestinal tract of animals — the so called ‘passage time’ (1–3). It has been suggested that this passage time increases with increasing body mass (4) — i.e., larger animal species should have longer passage times than smaller animal species. Because digestive efficiency is a function of the time available for digestion (5,6), it follows that larger animals should be able to achieve higher digestibilities than smaller animals. Surprisingly, empirical evidence does not support this line of reasoning (7,8).

Clauss M, Froeschle T, Castell J, Hummel J, Hatt JM, Ortmann S, Streich WJ (2005) Fluid and particle retention times in the black rhinoceros (Diceros bicornis), a large hindgut-fermenting browser. Acta Theriol 50:367– 376 Clauss M, Schwarm A, Ortmann S, Streich WJ, Hummel J (2007) A case of non-scaling in mammalian physiology? Body size, digestive capacity, food intake, and ingesta passage in mammalian herbivores. Comp Biochem Physiol A 148:249–265 Clauss M, Nunn C, Fritz J, Hummel J (2009) Evidence for a tradeoff between retention time and chewing efficiency in large mammalian herbivores. Comp Biochem Physiol A 154:376–382 Clauss M, Lang-Deuerling S, Mu¨ller DWH, Kienzle E, Steuer P, Hummel J (2010) Retention of fluid and particles in captive tapirs (Tapirus spp.). Comp Biochem Physiol A 157:95–101 Foose TJ (1982) Trophic strategies of ruminant versus nonruminant ungulates. PhD Thesis, University of Chicago Hume ID (2005) Concepts of digestive efficiency. In: Starck JM, Wang T (eds) Physiological and ecological adaptations to feeding in vertebrates. Science Publishers, Enfield NH, pp 43–58 Illius AW, Gordon IJ (1992) Modelling the nutritional ecology of ungulate herbivores: evolution of body size and competitive interactions. Oecologia 89:428–434 Justice KE, Smith FA (1992) A model of dietary fiber utilization by small mammalian herbivores, with empirical results for Neotoma. Am Nat 139:398–416 Length: 117 words (723 characters, including spaces)

1. Clauss M, Lang-Deuerling S, Mu¨ller DWH, Kienzle E, Steuer P, Hummel J (2010) Retention of fluid and particles in captive tapirs (Tapirus spp.). Comp Biochem Physiol A 157: 95–101 2. Foose TJ (1982) Trophic strategies of ruminant versus nonruminant ungulates. PhD Thesis, University of Chicago. 3. Clauss M, Froeschle T, Castell J, Hummel J, Hatt JM, Ortmann S, Streich WJ (2005) Fluid and particle retention times in the black rhinoceros (Diceros bicornis), a large hindgut-fermenting browser. Acta Theriol 50: 367–376 4. Illius AW, Gordon IJ (1992) Modelling the nutritional ecology of ungulate herbivores: evolution of body size and competitive interactions. Oecologia 89: 428–434 5. Clauss M, Schwarm A, Ortmann S, Streich WJ, Hummel J (2007) A case of non-scaling in mammalian physiology? Body size, digestive capacity, food intake, and ingesta passage in mammalian herbivores. Comp Biochem Physiol A 148: 249–265 6. Hume ID (2005) Concepts of digestive efficiency. In: Starck JM, Wang T (eds) Physiological and ecological adaptations to feeding in vertebrates. Science Publishers, Enfield NH, pp 43–58 7. Justice KE, Smith FA (1992) A model of dietary fiber utilization by small mammalian herbivores, with empirical results for Neotoma. Am Nat 139: 398–416 8. Clauss M, Nunn C, Fritz J, Hummel J (2009) Evidence for a tradeoff between retention time and chewing efficiency in large mammalian herbivores. Comp Biochem Physiol A 154: 376–382

Length: 93 words (594 characters including spaces)

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for this may be that if more than one reference is cited for one point, the reader who wants to pursue more information related to it finds these references at a glance listed one after the other in the reference list. However, this only works well if each reference is cited just once, and a bibliography ‘in the order of appearance’ incurs other difficulties (see below). Another, probably more pressing, concern when choosing a reference style is the space constraints under which publishers of scientific texts have to operate. Note that the Vancouver-style version of the short text example in Table 2 is already distinctly shorter (by twenty-four words or 20.5 per cent) than the Harvard-style version. Given the competition for scientific recognition, such space constraints may particularly apply to high-ranking journals; it is therefore no surprise that many journals with impact factors close to 30 and above have consequently adopted the Vancouver style. Even in the age of electronic publishing, space is a valuable asset and may be the most important argument for the Vancouver style today. For example, the completely electronic ‘Public Library of Science’ (PLoS) series has adopted the Vancouver style.

educational aspects: reference style and introduction to a research field As a scientist develops, a referencing system evolves in the mind. This referencing system is the true mark of scholarship: Whereas laymen usually store ‘only’ facts or opinions in their mind, scholars store these together with the source reference and, possibly, additional information about the quality of these sources. This mind-map is an essential working tool, and uses, in our experience, as reference points the most unique indexing features of a source — usually, the author names. The Harvard style actively helps to establish this mind-map. For each fact mentioned in a publication, the reader automatically absorbs the name and the year of the source. The hopeful aspirant in comparative digestive physiology will, when reading the Harvard style version of the text in Table 2, automatically assume that the names ‘Foose,’ ‘Hume,’ ‘Illius and Gordon,’ ‘Justice and Smith,’ and those of our own group (Clauss et al.), represent important research produced by these authors in this particular academic field (for the potential dangers of this assumption, see the next section below). When reading several articles on the topic, in which some of these names appear repeatedly, the citations will help the reader


consolidate a mind-map that may be expanded and refined with each new scientific text that is processed. The Vancouver style does not enhance the formation of a mind-map in a similar way, because it does not allow for an easy absorption of source references simultaneous to the reading of the text. The development of a mind-map is not restricted to the reading of the text alone. Scanning the reference list of scientific articles is an important part of scientific reading, either as part of a literature review or in the attempt to gain an overview of the topics covered by other researchers in the field. Scanning the reference list formatted in Harvard style in Table 2, for example, provides the insight that our group has been involved in both experimental work with individual species and comparative synthesis work with a plethora of species; further, the temporal sequence suggests that we keep striving to add more species to the data collection (we discuss the potential for a less favourable insight concerning our group in the next section below). This kind of information is an important part of the scientist’s mind-map. It is evident that such conclusions would be much more difficult to draw from reference list formatted in Vancouver style in Table 2.

editorial/quality aspects: reference style and good scientific practice It is not only the establishment of a mind-map in the aspiring scientist but also the continual development and application of the existing mind-map of the established scientist that is affected by the reference style. Being exposed to the Harvard style broadens the reading process of the trained scientist to a constant comparison of his or her own mind-map with the text; for the established scientist, this results not only in a constant readjustment of the mind-map but also in a judgement of the scientific quality of the text at hand. In the example in Table 2, an informed reader of the text in Harvard style would immediately realize that two important references are missing: Demment and Van Soest (1985) were probably the first authors to elaborate the concept that passage times are related to body mass, and a seminal study by Pe´rez-Barberıà et al. (2004) demonstrated a lack of correlation between body mass and digestive efficiency.5 After noticing that a reference is missing from a text formatted in Harvard style, a reader familiar with the topic could scan the alphabetically-sorted reference list for the source

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in his/her mind and quickly determine whether the source is included somewhere else in the text. In a document formatted in the Vancouver style, the presence of a certain reference cannot be easily determined, as a quick scanning of a reference list, which is sorted not by a universal principle but by the order of citations in the text, is not feasible. In an ideal academic world, therefore, a Harvard-style system of referencing sources would be commonplace, in our view, because of these two effects: constant education of, and easy quality control by, the scientific reader. Both effects are theoretically possible with the Vancouver style, but they require much more time and initiative on the part of the reader in that context. Scientific readers may find this style difficult to use if they want to check and verify sources regularly during reading (i.e., when they want to use their own mind-map). For reviewers, who cannot opt not to make such checks, the Vancouver style is even more tedious. As already stated, it requires constant moving from text to reference list and back again, and it does not lend itself to a quick scan of whether a particular source is included, due to the lack of a universal sorting principle. Thus, important source references absent from a text and poor literature research (both signs of bad scientific practice) are more difficult to detect in the Vancouver style. At the same time, hiding the practice of excessive self-citation is also easier in the Vancouver style: Note that in Table 2, the Harvard-style reference list shows at one glance that 50 per cent of all source references are works by our own group. This may be a reflection of our own importance in this field (not true) or reflect the (here intentional) attempt to inflate our own importance. Such practice is far less easy to spot even in the short Vancouver-style list in Table 2.

conclusions and suggestions Developing a mind-map of source references for a particular research field is not only an important tool for scientists but also a gratification in itself, as one gains a sense of evolving competence. Comments on sourcereferencing systems tend to stress the downsides of these systems — how difficult they are to master, how confusing the large number of styles are (within the Harvard- or the Vancouver-style groups), how much proper source referencing is considered an indication of a student’s suitability for research work, and how much it is therefore conceived by students (and others) as a gatekeeping skill that may decide whether they are


granted access to academia.6 Source referencing thus appears to be a ‘necessary evil,’ whereas, in our view, it is a state of mind — the state of a mind that is organized in a systematic way that reflects the (potentially constantly growing) competence of the mind’s owner, and that is therefore an inspiring, gratifying goal at which to aim. Enhancing this individual development through the use of a Harvard source-referencing style is one way to enhance competence accretion in scientists and the attraction and gratification of scientific life in general. Slowing down this individual development through the use of a Vancouver reference style — which prevents the automatic generation of a mind-map — reduces the attraction and gratification of scientific life and may lead to greater adoption of the ‘necessary evil’ view with respect to referencing. For the review process, the Harvard style is a precondition for the best use of one of the most important tools that the reviewer has to judge the quality of a manuscript: his or her mind-map. Of course, the demand to minimize printing space is also justified, and the Vancouver style will persist, if only for this reason. However, journals using it in print should use the Harvard style for the reviewing process ( just as most authors who have to produce Vancouver style manuscripts usually write in Harvard style and reformat the references prior to submission) as switching between styles in submission versions and versions prepared after acceptance is no longer a technological challenge. For Vancouver-style bibliographies, it is also essential that a consensus is reached across the board; we believe consensus should converge on reference lists numbered and sorted alphabetically (as actually done by various journals), to ensure these lists can be used with optimal efficiency. marcus clauss, dennis mu¨ ller, and daryl codron were postdoc researchers at the Clinic of Zoo Animals, Exotic Pets and Wildlife at the Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057 Zurich, Switzerland. While Marcus Clauss ([email protected]) is still working there, his colleagues have moved on (Dennis Mu¨ller to the National Park ‘Bavarian Forest,’ Freyunger Str. 2, 94481 Grafenau, Germany, and Daryl Codron to the Florisbad Quaternary Research, National Museum, Bloemfontein, 9300, South Africa). Mentoring postgraduates in the development of their scientific skills is one of the major endeavours of the clinic. notes 1. ‘Reference Styles (BMA Library Factsheet),’ British Medical Association (n.d.), http://bma.org.uk/about-the-bma/bma-library/ask-for-help/reference-styles.

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Journal of Scholarly Publishing 2. C. Neville, The Complete Guide to Referencing and Avoiding Plagiarism (Maidenhead, Berkshire, UK: Open University Press 2007) 3. E. Chernin, ‘The ‘‘Harvard System’’: A Mystery Dispelled,’ British Medical Journal 297 (1988): 1062–3 4. ‘Reference Styles: Harvard and Vancouver’ 5. M. W. Demment, P. J. Van Soest, ‘A Nutritional Explanation for Body Size Patterns of Ruminant and Nonruminant Herbivores,’ American Naturalist 125 (1985): 641–72; F. J. Pe´rez-Barberıà, D. A. Elston, I. J. Gordon, A. W. Illius, ‘The Evolution of Phylogenetic Differences in the Efficiency of Digestion in Ruminants,’ Proceedings of the Royal Society B 271 (2004): 1081–90 6. J. Sanders, ‘Horray for Harvard? The Fetish of Footnotes Revisited,’ Widening Participation and Lifelong Learning 12 (2010): 48–59