Evolution of number of citations per article in Materials Science: possible causes and effect on the impact factor of journals

Vol.:(0123456789) Scientometrics (2023) 128:6589–6609 https://doi.org/10.1007/s11192-023-04863-7 1 3 Evolution ofnumber ofcitations perarticle inMaterials Science: possible causes andeffect ontheimpact factor ofjournals AnaM.Ariza‑Guerrero1· J.SebastiánBlázquez2 Received: 26 April 2023 / Accepted: 23 October 2023 / Published online: 7 November 2023 © The Author(s) 2023 Abstract An overall rise in the citation parameters used in the metrics of scientific publications (i.e. journal impact factor, JIF) has taken place since the last decade of the previous century, coinciding with the electronic distribution of (and access to) scientific literature. This inflation like tendency is herein analyzed in the area of Materials Science and also affects the number of publications. Considering average JIF values, its growth is proportional to the number of publications in the area and to its JIF value, leading to an inhomogeneous boost that preferentially benefits those journals with high JIF. An elevation in the number of publications per year alone cannot explain this behavior but it occurs due to a continuous and widespread increment in the number of citations per article, which only remains limited when restrictions are applied by journals to the maximum number of pages per article. In this work we observe this positive correlation between the increase in the number of references per article and the overall increase in JIF but, in our analysis, a kink point is observed in consistency with the appearance of online databases, particularly those free available in 2004. Online databases along with the widespread of open access publishing option made the research content easily available to the scientific community contributing to an increasing trend (without apparent saturation) in the number of articles used to contextualize the new scientific contributions. Keywords Citations· Materials Science· Bibliometrics· Web of science database· Journal citation reports * J. Sebastián Blázquez [email protected] 1 Biblioteca de La Universidad de Sevilla, Universidad de Sevilla, P.O. Box1065, 41080Seville, Spain 2 Dpto. Física de La Materia Condensada, Universidad de Sevilla, P.O. Box1065, 41080Seville, Spain 6590 Scientometrics (2023) 128:6589–6609 1 3 Introduction Publication of scientific articles can be considered a final product in the scientific activity. In this sense, they are tangible results easy to be managed and evaluated by the Administration Authorities responsible for the financial support and academic career of researchers. Despite the evident incompleteness in the description of the progress in Science (MacRoberts & MacRoberts, 2018), bibliometric studies based on citation and journal metrics, and developed by Garfield (Garfield, 1955), allow for these comparative analyses. In 1976, the Institute for Scientific Information, ISI, launched Journal Citation Reports (JCR) as a tool to compare and rank the scientific journals. JCR orders the journal by relevance attending to the so-called journal impact factor, JIF . The definition of JIF for a certain journal in a year y is JIF (y)= N cites (y) N(y−1)+N(y−2) , where Ncites(y) corresponds to the number of citations in year y to articles published in the journal in years y−1 and y−2 , whereas N(z) is the number of articles published in year z in that very journal. Thus JIF corresponds to the ratio between citations to articles published in the two previous years and the number of articles published in that period. Understanding JIF dependencies is of particular interest to both individual researchers and institutions. The influence of JIF on the way researchers publish their results has been huge, as it offers a quantitative and friendly usable frame to science founding administrations affecting salary, career promotions, resources distribution and prestige, despite it is not at all free from criticism (Dunleavy, 2022; Gorraiz etal, 2022; Law & Leung, 2020; MacRoberts & MacRoberts, 2018). For certain article to be cited, its availability and easy distribution to possible users are crucial. This necessity of the scientific community to spread out its research achievements early motivated the development of ArXiv repository (Elizalde, 2021; Ginsparg, 2011). Physicist at CERN contributed to the development of internet and the World Wide Web (although invented in 1989 by the physicist Tim Berners-Lee, World Wide Web Consortium was founded in 19941). This milestone supplied an extraordinarily effective tool that changed for good humankind thinking with respect to immediate access to information. The reaction of ISI to the birth of internet was the development of Web of Science (WoS) platform in 1997, nowadays collecting information from different databases dating back to 1900. Since the appearance of WoS, databases consulting was easily available to every researcher with a computer and internet access, which did revolutionize the literature research and checking for scientist. Other competitors appear later on, Scopus and Google Scholar, both in 2004 (Cantu-Ortiz, 2018). The former, developed by Elsevier, included an innovative link to the full text of the article, speeding up the literature checking. This was later adopted by WoS (which recently, since 2021, included links to the authors’ preprint “first online”). Scopus database and metrics (Citescore launched in 2016 and freely available (Fang, 2021)) have acquired enough relevance in academy to be competitive relative to WoS and considered for evaluation of the research. Both WoS and Scopus are available under subscription unlike the third academic search engine, Google Scholar, which is free. 1 https:// webfo undat ion. org/ about/ vision/ histo ry- of- theweb/ (access 24/03/2023). 6591 Scientometrics (2023) 128:6589–6609 1 3 Finally, open access publications, explicitly required by public funding in new calls (e.g. Horizon Europe2), contribute to the availability of research documents to a much broader scientific community (Ghane etal, 2020). These free accessible articles can be found in fully open access journals and, as a suitable option for the author, in an increasing number of conventional journals regularly distributed under subscription. Recent studies (Dorta- González etal, 2020) do not find any deleterious effect on the open access articles, comparing the uncited articles whether they were open access or available under payment, except for the extreme quartiles, for which freely accesible articles are less (Q1) and more (Q4) uncited that those articles available under subscription in the same quartile. Gray (Gray, 2020) discusses the effect of article processing charges (APC) on generating inequalities between different countries depending on their wealth. In this sense, free repositories from public institutions (e.g. idus.us.es from University of Sevilla) are now promoted by public research investors.3 Finally, altmetrics (interest from social media) correlations with open access and no-open access journals has also received some interest in recent works (Bray & Major, 2022; Vadhera etal, 2022; Wang, 2022). Garfield already identified the importance of the average number of references to define the citation potential of a category (Garfield, 1979) and several studies proposed normalized factors such as the audience factor (Zitt & Small, 2008), the source normalized impact per paper (Moed, 2010) and the reference return ratio (Nicolaisen & Frandsen, 2008; Yuret, 2018). However, despite several works have analyzed the effect of number of references per article in the number of citations received and the corresponding JIF , conclusions are not really clear and disagreement can be found between them. Among those reporting a positive correlation between larger number of references and higher JIF , Haslan and Koval (2010) found it for Social and Personality Psychology articles published in 1998. This correlation was also observed for Nanoscience and Nanotechnology journals (Didegah & Thelwall, 2013a) and for Biology and Biochemistry, Chemistry and Social Sciences ones (Didegah & Thelwall, 2013b). Finally, and more recently, Zhou etal. (2020) used Montecarlo simulations to support this interpretation. Mammola etal. (2022) recently reported several factors affecting citation, including the number of references. However, several papers found that other parameters are more determinant than the number of references. Dorta-González and Dorta-González (2013) reported that the number of references per paper does not explain the differences between impact factors among categories. Falagas etal. (2013) analyzed citations in general medicine journals but unlike number of references, article length and number of authors were used to predict, independently, the number of citations. Patience etal. (2017) studying the 500 articles with more citations in different categories found more relevant the age of the references than their number with a higher number of citations for those articles that cite recent research. Finally, no conclusive results are reported in a recent work on Biomedical research (Urlings etal., 2021) concerning the number of references as determinant for citation bias. The aim of this work is to show the coincidence between the overall increase in impact factor and the appearance of online databases and open access publications that allow the scientific community to easily and quickly access to scientific content to contextualize the new scientific contributions. This is shown for the JCR category of Materials Science, Multidisciplinary and particularly for several journals of the category. We compare 2 https:// resea rch- and- innov ation. ec. europa. eu/ fundi ng/ fundi ngoppor tunit ies/ fundi ngprogr ammes- and- opencalls/ horiz oneurope_ en (Access 25/04/2023). 3 https:// ec. europa. eu/ info/ resea rch- and- innov ation/ strat egy/ strat egy- 2020- 2024/ ourdigit alfuture/ openscien ce/ openaccess_ en (Access 25/04/2023). 6592 Scientometrics (2023) 128:6589–6609 1 3 the evolution of regular articles and letters and proceeding contributions, the latter being limited in maximum number of pages, which indirectly limits the number of references per article. Both types of articles, independently whether they are limited in the number of pages or not, seem to be benefited from the overall increase in the number of references per article in the category. Databases used Herein Journals Citation Reports (JCR) and Web of Science (WoS) resources from Clarivate have been used to obtain the data concerning the category Materials Science, Multidisciplinary (category Materials before year 2000). Results have been limited to Science Citation Index Expanded (SCIE) and final date of searching 01/28/2022 (unless explicitly indicated). Concerning the analysis of the number of references per journal, we have excluded review articles as well as corrections, retractions, and editorials. This analysis has been limited to publications defined as articles but it also includes articles from proceedings. Five different journals have been taken as examples for a more detailed analysis. Overall analysis oftheCategory Materials Science, Multidisciplinary Time evolution oftheCategory Materials Science, Multidisciplinary From JCR database, the category of Materials Science, Multidisciplinary (in the following MSM) appears in 2000. However, using WoS database, it is possible to perform a search for “Materials Science, Multidisciplinary (Web of Science Categories)”, limited to SCIE, which returns results since 1900. WoS selection of journals has evolved with time. From 1900 up to 1944 a single journal is found in MSM: Philosophical Magazine (Taylor & Francis), which is still active. Table1 collects the publishers with highest production in the category along with their respective country and the first year they appear in WoS (MSM search). Possible bias in WoS has been claimed favoring English language journals (Mac- Roberts & MacRoberts, 2018) and its effects are recently analyzed in Social Science Citation Index data base (Vanderstraeten & Vandermoere, 2021). Figure 1a shows the evolution in the number of journals in MSM category (taking into account that the values before 2000 correspond to “Number of Publication Titles” as ascribed by WoS to this category). Figure1a also shows the number of articles per journal and Fig.1b shows the number of articles per year in MSM category along with the percentage of the number of open access articles. Globally, from over 2.28·106 articles collected in MSM (search in WoS June, 16th 2023), about 20% (0.45·106 articles) are open access. A first rise in the number of journals in the category is observed after 1960 when the journals in MSM exceeded 10 and the articles published per year rapidly increased, coincidentally, one order of magnitude. However, since the 90’s, contemporary to the development of internet (Zhang, 1998), an exponential rise is continuing up to date in both the number of articles and the number of journals assigned to the category. Since 1990, the number of articles per journal in a year has also steadily increased, being nowadays roughly fivefold the value before 1980. This increment is statistically meaningful and must be linked to the increase of scientific demand for publication space, which exceeds the 6593 Scientometrics (2023) 128:6589–6609 1 3 offer from increasing the number of journals. Moreover, the availability of such space was offered by less limited electronic journals (e.g. Interpersonal Computing and Technology Journal in 1993 (Collins & Berge, 1994). Nowadays, almost every journal has electronic version. These versions rapidly overcame the distribution of printed versions (Trajkovski, 2018). Electronic journals available inMaterials Science, Multidisciplinary Concerning the subject category of interest in this work, MSM, among the 414 journals listed in 2021 JCR, only 14 (3.4%) do not have an e-ISSN but only two of them do not directly have a link in their web page to full content (SAMPE journal and Journal of Materials Education, both in Q4). On the other hand, 49 journals (11.8%) only have an e-ISSN. Among these journals, 27 are still in the Emerging Source Citation Index (ESCI) and do not have a JIF . That database appeared in 2015 to account for the rapidly emerging academia journals and collects the journals that meet the 24 quality criteria of WoS but not the 4 other impact criteria that would allow the journal to be included in Science Citation Index Expanded (SCIE) (Huang etal, 2017; Filipo & Gorraiz, 2020). However, these journals have the new Journal Citation Indicator ( JCI ) which is the normalized impact factor Table 1 Production collected in SCIE of the main publishers contributing to MSM category (without restrictions; date of search 06/16/2023) * Last year 2004; ** Last year 1997; *** Last year 2006 Publisher Production (Nr. Items) % MSM 1st year in WoS Country Elsevier 819,615 31.67 1952 The Netherlands American Chemical Society 271,730 10.50 1985 USA American Physical Society 210,665 8.14 1964 USA Springer Nature 197,928 7.65 1966 Germany Wiley 149,948 5.79 1970 USA Taylor & Francis 133,595 5.16 1900 UK MDPI 132,190 5.10 2008 Switzerland Royal Society Chemistry 107,242 4.14 1990 UK IOP Publishing Ltd 65,687 2.54 1986 UK American Scientific Publishers 30,857 1.19 2001 USA Trans Tech Publication 18,571 0.72 1989 Switzerland Northwest Institute for Nonferrous Metal Research (NIN) 16,703 0.65 1997 China Minerals Metals Materials Society (TMS) 16,552 0.64 1974 USA Akademie Verlag Gmbh 14,756 0.57 1972** Germany Cambridge University Press 14,650 0.57 1986 UK IEEE 13,192 0.51 1970 USA Kluwer Academic Publishers 13,043 0.50 1969* The Netherlands American Institute of Physics 12,445 0.48 1994 USA Maik Nauka/Interperiodica 11,703 0.45 1976*** Russia Sage 11,595 0.45 1967 USA Hindawi Publishing Group 11,040 0.43 2006 United Kingdom 6594 Scientometrics (2023) 128:6589–6609 1 3 of the corresponding category (Huh, 2021). The normalized index was proposed to allow comparing between different categories. This avoids the boost behavior observed in JIF . Among the 49 e-ISSN journals only with electronic version, 12 are in the Q1 of the MSM category. Concerning the capability of electronic journals to increase the number of articles per year, whereas the average number of articles per journal in 2021 in MSM was 326, this number increased to 675 when considering those 49 journals only with e-ISSN. An even higher value of 1109 articles per journal is obtained discarding from this set those journals without JIF. Studies on the effect of electronic sources on the scientific production and citation appeared soon after the rise in number of electronic sources, e. g. Zhang (Zhang,1998) analyzed the period from 1994 to 1996 in the in the area of Library and Information Science. At that moment, they found some bias for articles published in electronic journals to cite more articles published in that sort of journals than it occurs for articles published in print journals. Nowadays, more than 25years ago almost all the other journals in the category have an available electronic version. Fig. 1 a left axis:Number of journals in “Materials Science, Multidisciplinary” category as a function of the year of publication. Solid symbols correspond to data from JCR (starting in 2000). Hollow symbols correspond to data from WoS (available from 1900 and here limited to 2000); and right axis: number of papers per journal. b left axis: Number of articles (black solid squares) and open access articles (red solid circles); and right axis: percentage of open access articles (green hollow circles) as a function of the year of publication. Data taken June 16th, 2023. (Color figure online) 6595 Scientometrics (2023) 128:6589–6609 1 3 Open access articles inMaterials Science, Multidisciplinary Finally, it is worth mentioning the relevance that open access articles, including those from open access journals as well as those individually selected as open access (see Fig.1), are acquiring with respect to the total number of publications, reaching 40% in 2021. This indicates increasingly large and easily accessible information freely available to the research community of this scientific area. The role of electronic journals is crucial also to understand the immediacy of access to new results from the scientific community which is directly affecting the overall increase of JIF (Althouse etal, 2009; Trajkovski, 2018). Nowadays, journals anticipate the publication of the articles as preprints or uncorrected proofs. In some cases, this provisional version can be accessed the year previous to its volume publication and this could affect the corresponding JIF calculation. This will be briefly commented in next section when analyzing the five selected journals of this study. We compare the behavior of two journals with similar JIF but one open access (Metals from MDPI, JIF =2.695 ) and other distributed under subscription (JOM, from Springer, JIF =2.597 ) both in Q3. In 2020, Metals published 1699 open access articles and was cited till now (April 12th 2023) by 11,535 articles. In the same year, JOM published 543 articles from which 178 were open access. The remaining 365 articles were cited by 1893 articles, whereas the 178 open access articles were cited by 893 articles (differences in the ratio are not significant). In both cases self-journal citation is the highest contribution (13.3 and 5.2% of the total citations for Metals and JOM, respectively). Considering only those journals that represent above 0.5% of the total citations to articles published in 2020 in Metals and JOM (summing up to 50.2 and 41.9% of the total citations), we found that from them, open access journals represent 3/5 for Metals and less than ¼ for JOM. Limiting the citing articles only to open access (independently of the open access character of the journal), we found 55% of citations to Metals come from open access articles, whereas only 35% of citations to JOM articles corresponds to open access articles. Recently, Momeni etal. (Momeni etal., 2021) concluded that the shift to open access of journals generally led to an enhancement in their bibliometric qualification. Quantitative evolution ofjournal impact factor inMaterials Science, Multidisciplinary Figure2 shows the correlation between mean JIF values for the different quartiles of MSM and the total number of publications in the MSM category, NMSM , for the corresponding year of publication. Both parameters exponentially increase with time (see Fig.1 for NMSM ) and they are linearly correlated. As it is shown in the inset of Fig.2, the slope of the linear dependence observed for ⟨JIF⟩ versus NMSM , for the same period of time (2000–2020), linearly increases with mean impact factor, ⟨JIF⟩ , for a certain range (e.g. Figure2 shows this for the quartiles but this can be extended for any region where a < JIF < b ). Therefore: where k=( 6.71 ± 0.15 ) 10 −6 and the subindex indicates the [a,b] range analyzed (in Fig.2 they corresponds to the different quartiles and the values over whole MSM). From this normalization law, it can be inferred that, as a first approximation, the increase in JIF is proportional to the number of publications in the category and to JIF . This relative change Δ⟨JIF⟩ [a,b] N MSM =k ⟨ JIF ⟩ [a,b] , 6596 Scientometrics (2023) 128:6589–6609 1 3 in the average JIF in a certain range proportional to the number of articles published in the category ( Δ⟨ JIF ⟩[a , b] ∕ ⟨ JIF ⟩[a , b] =kN MSM ) is an indication of the non-homogenous distribution of citations over the journals in the category but those with a higher JIF are more benefited than those with a lower one as it is evident from the increasing slopes of the fitted straight lines to the data of different quartiles in Fig.2. This preferential increase is shown in Fig.3a which plots the increase in JIF from 2000 (first appearance of MSM category) to 2020 (i.e. ΔJIF =JIF[2020]−JIF[2000] as Y axis) for the 106 journals that belong to MSM during that period as a function of their corresponding JIF in 2020 (i.e. JIF[2020] as X axis). Increase in JIF calculated without self-citations is also shown. We can find a linear correlation for both, which allows us to estimate an expected average ⟨ΔJIF⟩ increase as a function of JIF value in 2020. Figure3b shows the deviation of each journal with respect to its corresponding average value as a function of the increase in the number of articles of the journal per year. We can find that most of the journals in MSM have increased their number of articles per year but there is no clear correlation between this parameter and the deviation of actual increase in JIF with respect to the expected ⟨ΔJIF⟩ of the journal from 2000 to 2020. An overall increase in the number of articles in the category should lead to an expected increase in the number of citations as there are more documents published on the subject and, therefore, susceptible to cite articles published in the journal of interest. For example, assuming that, on average, an article published one or two years before the calculation year y in the journal A has a probability to be cited in year y equal to p(A,y) by a research developed in the area and published in that year y , Ncites(A,y) can be related with the total number of articles published in the category as Ncites(A,y)∼p(A,y)NMSM(y) (neglecting citations from papers from out of MSM categories). However, the increase in number of articles per year in the journal would be deleterious for JIF as it appears in the denominator of its definition. In the period from 1997 to 2020, the whole number of articles per year in MSM, NMSM(y) , increased with a ratio N MSM (2020) NMSM ( 1997 ) = 4.42 , whereas ⟨JIF⟩ ratio increased ~ 6, independently of the quartile range. Moreover, as shown in Fig.1, the number of articles per journal has shown an overall increase with time with a ratio of 2.55 in the period from 1997 to 2020. Therefore, from these ratios we can explore the evolution of the probability of an article in an average journal A to be cited by a research in the MSM category, p(A) , in the two years following its publication: Fig. 2 Evolution of the ⟨JIF⟩ as a function of the year for the total MSM category and for each of the different quartile ranges. The inset shows the linear correlation between the slope of the straight lines in the main panel and the corresponding ⟨JIF⟩ in 2020 6597 Scientometrics (2023) 128:6589–6609 1 3 This equation indicates that the probability of an average journal A in MSM category to be cited in an article in the category has decreased in 2020, being 53% of that in 1997, even though the value of JIF has steadily increased. Anyhow, as the total number of articles in MSM increases with time, the number of citations increased in 2020 to be close to threefold that of 1997. JIF (2020) JIF (1997)=Ncites(A, 2020) Ncites(A, 1997)(N(A, 1996)+N(A, 1995) N(A, 2019)+N(A, 2018)) =p(A, 2020)NMSM(2020) p ( A , 1997) NMSM (1997) ( N(A, 1996)+N(A, 1995) N ( A , 2019)+ N ( A , 2018) ) ∼11.3 p(A, 2020 ) p ( A , 1997 ) Fig. 3 a Increase in JIF from 2000 to 2020 for each journal active in MSM category during this period (total 106 data) as a function of JIF value in 2020. b Deviation of actual JIF from expected JIF from linear behavior from (a) as a function of relative increase in the number of articles published from 2000 to 2020 6604 Scientometrics (2023) 128:6589–6609 1 3 before 2018 (due to the average delay of about 3 to 4years of an article to be used by the community). Delay time from submission to final publication is also affecting the availability of the research to the scientific community. Table3 collects the characteristic times for the different journals analyzed here. Time to first decision, review time and publication time are taken from the corresponding web pages of the journals. As described in the journal web page, time to first decision includes rejected articles, which in the case of desk rejects might be particularly short times. Therefore, this time is much longer for any contribution which is finally published. Analogously, review time also considers rejects, including desk rejects, and for any published article must be longer. Finally, the interesting time for this study is the time from online availability to issue publication. This parameter is not directly available for each journal but this information is supplied for each individual article. Therefore, we have estimated this time from averaging the corresponding time gap for the articles published in the last completed issue at the moment of redaction of these lines Fig. 8 Self JIF for the different journals analyzed herein. a SJIF (in %) calculated as the relative difference between JIF calculated using all citations and excluding citations from the very journal. b rself JIF , calculated as the normalized value of SJIF once considered the number of articles published in the corresponding year in that journal 6605 Scientometrics (2023) 128:6589–6609 1 3 (15th June 2023). The error shown in the last column of Table3 corresponds to the average deviation from the average value in the corresponding issue. Although the article is available since it is published online, JIF calculation is referred to the full reference date of publication. Among the analyzed journals, this time is always above 2 months and can be as large as 5months for JAC. This anticipation is typically found independently of the publisher: e.g. combining April and May 2023 issues of top journal of MSM Nature Materials (Springer), which publishes regular articles, the average time from online publication to issue date is roughly 50days. However, the average deviation is also around 50days and some articles are available less than 10days previous to issue date, whereas other articles of the same issue are available more than 200days earlier. This anticipation in publishing gives the articles an extra time of visibility that will contribute to an enhancement in the citations during the period time considered for the calculation of JIF . Fig. 9 Citations per article per year as a function of the number of references for articles published in the five analyzed journals. Small dots correspond to individual articles and large symbols to average values over each year Table 3 Characteristic times of the different journals analyzed in this study * AM estimated from the complete issue: Volume 254, 1 August 2023 (34 articles) ** SM estimated from the complete issue: Volume 234, September 2023 (44 articles) *** JAC estimated from the complete issue: Volume 959, 10 October 2023 (60 articles) **** ML estimated from the complete issue: Volume 348, 1 October 2023 (54 articles) ***** JMMM estimated from the complete issue: Volume 579, 1 August 2023 (44 articles) Journal Time to first decision (weeks) Review time (weeks) Online publication time (weeks) Time from online to issue publication (days) Acta Materialia 4.5 7.6 0.5 84 ± 6 Scripta Materialia 3.2 4.9 1.2 101 ± 7 J. Alloys and Compounds 3.3 5.4 0.5 155 ± 5 Materials Letters 4.9 7.2 0.5 148 ± 4 J. Mag. & Mag. Mater. – 8.5 1.1 71 ± 6 6606 Scientometrics (2023) 128:6589–6609 1 3 In this sense, journals are now supplying access to preliminary versions of the articles (i.e. previous to assignment of volume and publication date) that makes this contribution to be known by the scientific community in advance. This can affect the calculation of JIF , especially when preliminary versions are available in the previous year than the publication date. On the other hand, Shi etal. (2017) showed that time gap between the submission and final publication of the articles can lead to inaccuracies in JIF calculation. Guo etal. (2021) have recently analyzed this negative effect on JIF and proposed a delay adjusted impact factor. They found a better match between corrected JCR ranking and highly reputed journals (e.g. NATURE INDEX, UTD 24). Conclusions A general increase in the number of references cited per article is found in the Materials Science, Multidisciplinary WoS category since, roughly, 2005. This occurs one year after the development of Scopus database that supplied a rapid access via a link to the full content (under subscription in most cases) of the research documents. However, when the number of articles is restricted, this indirectly affects the number of references made per article without which it is impossible to explain the notable continuous rise in the journal impact factors that, on average, grows linearly with the number of articles published in the category. It is also quite evident that higher the impact factor of the journal, greater the increase rate. This increment in impact factor takes place despite the steady rise in the number of articles published per year in many journals. The number of articles per year of two cases studied here, Acta Materialia and Scripta Materialia, remained stable. They both gained two advantages, the increase in the number of articles published in the category and the number of references per article in journals of the category without the increase in their corresponding denominators of the JIF formula which explains their particular above average JIF level. The simplicity of access and the immediate availability of the results of scientific research through World Wide Web is one of the key factors in the overall growth of the number of references cited. In this sense, database platforms such Web of Science (1997), Scopus (2004) or Google Scholar (2004) have provided us a tremendously successful tool. Open access journals and free scientific reservoirs, explicitly required by public funding in new calls, makes even more accessible scientific research to researchers. Taking the advantages of reduced costs and flexibility of online publication, publishers are now anticipating the availability of the scientific results with respect to the correct citation date of publication of the corresponding issue which leads to a factual extension of the valid time for an article to be cited in the period time considered to calculate JIF . However, several questions are open with respect to this apparently inflationary behavior. Is a saturation behavior expected? In our personal experience, the real amount of scientific content of research articles has not increased with time but the contextualization of the research has. In fact, the pressure felt by researchers to publish throughout their career (e.g. CV evaluation strongly dependent on the number of publications) is in 6607 Scientometrics (2023) 128:6589–6609 1 3 contradiction with the accumulation of scientific results that would justify longest articles with a long reference list. Author contributions All authors contributed to the study conception and design, as well as material preparation, data collection and analysis. The first draft of the manuscript was written by both authors and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. AMA-G: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Writingoriginal draft & review editing; JSB: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Writing-original draft & review editing. Funding Funding for open access publishing: Universidad de Sevilla/CBUA. Declarations Conflict of interest The authors declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this article. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. References Althouse, B. M., West, J. D., Bergstrom, T., & Bergstrom, C. T. (2009). Differences in impact factor across fields and over time. Journal of the American Society for Information Science and Technology, 60, 27–34. https:// doi. org/ 10. 1002/ asi. 20936 Baas, J., Fennell, C. (2019) When peer reviewers go rogue - Estimated prevalence of citation manipulation by reviewers based on the citation patterns of 69,000 reviewers, 17th International Conference of the International-Society-for-Scientometrics-and-Informetrics (ISSI) on Scientometrics and Informetrics, I, pp.963–974 Bray, N. J., & Major, C. H. (2022). Impact factors, altmetrics, and prestige, oh my: The relationship between perceived prestige and objective measures of journal quality. Innovative Higher Education, 47, 947– 966. https:// doi. org/ 10. 1007/ s10755- 022- 09635-4 Cantu-Ortiz, F. J. (2018). Research analytics. boosting university productivity and competitiveness through scientometrics. CRC Press. Collins, M. P., & Berge, Z. L. (1994). IPCT journal: A case study of an electronic journal on the internet. Journal of the American Society for Information Science, 45, 771–776. Costas, R., van Leeuwen, T. N., & van Raan, A. F. J. (2010). Is scientific literature subject to a ‘sell-by- date’? A general methodology to analyze the ‘durability’ of scientific documents. Journal of the American Society for Information Science and Technology, 61, 329–339. https:// doi. org/ 10. 1002/ asi. 21244 De Filippo, D., & Gorraiz, J. (2020). Is the emerging source citation index an aid to assess the citation impact in social science and humanities? Journal of Informetrics, 14, 101088. https:// doi. org/ 10. 1016/j. joi. 2020. 101088 Didegah, F., & Thelwall, M. (2013a). Determinants of research citation impact in nanoscience and nanotechnology. Journal of the American Society for Information Science and Technology, 64(5), 1055– 1064. https:// doi. org/ 10. 1002/ asi. 22806 Didegah, F., & Thelwall, M. (2013b). Which factors help authors produce the highest impact research? Collaboration, journal and document properties. Journal of Informetrics, 7, 861–873. https:// doi. org/ 10. 1016/j. joi. 2013. 08. 006 6608 Scientometrics (2023) 128:6589–6609 1 3 Dorta-González, P., & Dorta-González, M. I. (2013). Comparing journals from different fields of science and social science through a JCR subject categories normalized impact factor. Scientometrics, 95, 645– 672. https:// doi. org/ 10. 1007/ s11192- 012- 0929-9 Dorta-González, P., Suárez-Vega, R., & Dorta-González, M. I. (2020). Open access effect on uncitedness: A large-scale study controlling by discipline, source type and visibility. Scientometrics, 124, 2619–2644. https:// doi. org/ 10. 1007/ s11192- 020- 03557-8 Dunleavy, J. D. (2022). Progressive and degenerative journals: On the growth and appraisal of knowledge in scholarly publishing. European Journal for Philosophy of Science, 12, 61. https:// doi. org/ 10. 1007/ s13194- 022- 00492-8 Elizalde, E. (2021). (Spanish) Del preprint a la web: Una visión personal sobre los orígenes del ciberespacio. Revista Española De Física, 35(4), 2–14. Falagas, M. E., Zarkali, A., Karageorgopoulos, D. E., Bardakas, V., & Mavros, M. N. (2013). The Impact of article length on the number of future citations: A bibliometric analysis of general medicine journals. PloS one, 8(2), e49476. https:// doi. org/ 10. 1371/ journ al. pone. 00494 76 Fang, H. (2021). Analysis of the new scopus CiteScore. Scientometrics, 126, 5321–5331. https:// doi. org/ 10. 1007/ s11192- 021- 03964-5 Garfield, E. (1955). Citation indexes for science: A new dimension in documentation through association of ideas. Science, 122, 3159. https:// doi. org/ 10. 1126/ scien ce. 122. 3159. 108 Garfield, E. (1979). Is citation analysis a legitimate evaluation tool? Scientometrics, 1, 359–375. https:// doi. org/ 10. 1007/ BF020 19306 Ghane, M. R., Niazmand, M. R., & Sarvestani, A. S. (2020). The citation advantage for open access science journals with and without article processing charges. Journal of Information Science, 46, 118–130. https:// doi. org/ 10. 1177/ 01655 51519 837183 Ginsparg, P. (2011) It was twenty years ago today. arXiv: 1108. 2700v2 [cs.DL] http:// arXiv. org/ abs/ 1108. 2700v2 Glänzel, W., & Schoepflin, U. (1995). A bibliometric study on ageing and reception processes of scientific literature. Journal of Information Science, 21(1), 37–53. https:// doi. org/ 10. 1177/ 01655 51595 02100 104 Gorraiz, J., Ulrych, U., Glänzel, W., Arroyo-Machado, W., & Torres-Salinas, D. (2022). Measuring the excellence contribution at the journal level: An alternative to Garfield’s impact factor. Scientometrics, 127, 7229–7251. https:// doi. org/ 10. 1007/ s11192- 022- 04295-9 Gray, R. J. (2020). Sorry, we’re open: Golden open-access and inequality in non-human biological sciences. Scientometrics, 124, 1663–1675. https:// doi. org/ 10. 1007/ s11192- 020- 03540-3 Guo, X., Li, X., & Yu, Y. (2021). Publication delay adjusted impact factor: The effect of publication delay of articles on journal impact factor. Journal of Informetrics, 15, 101100. https:// doi. org/ 10. 1016/j. joi. 2020. 101100 Haslam, N., & Koval, P. (2010). Predicting long-term citation impact of articles in social and personality psychology. Psychological Reports, 106(3), 891–900. https:// doi. org/ 10. 2466/ PR0. 106.3. 891- 900 Huang, Y., Zhu, D., Lv, Q., Porter, A. L., Robinson, D. K. R., & Wang, X. (2017). Early insights on the Emerging sources citation index (ESCI): An overlay map-based bibliometric study. Scientometrics, 111, 2041–2057. https:// doi. org/ 10. 1007/ s11192- 017- 2349-3 Huh, S. (2021). The journal citation indicator has arrived for emerging sources citation index journals, including the journal of educational evaluation for health professions, in June 2021. Journal of Educational Evaluation for Health Professions, 18, 20. https:// doi. org/ 10. 3352/ jeehp. 2021. 18. 20 Krauss, J. (2007). Journal self-citation rates in ecological sciences. Scientometrics, 73, 79–89. https:// doi. org/ 10. 1007/ s11192- 007- 1727-7 Law, R., & Leung, D. (2020). Journal impact factor: A valid symbol of journal quality? Tourism Economics, 26, 734–742. https:// doi. org/ 10. 1177/ 13548 16619 845590 MacRoberts, M. H., & MacRoberts, B. R. (2018). The mismeasure of science: Citation analysis. Journal of the Association for Information Science and Technology, 69(3), 474–482. https:// doi. org/ 10. 1002/ asi. 23970 Mammola, S., Fontaneto, D., Martínez, A., & Chichorro, F. (2021). Impact of the reference list features on the number of citations. Scientometrics, 126, 785–799. https:// doi. org/ 10. 1007/ s11192- 020- 03759-0 Mammola, S., Piano, E., Doretto, A., Caprio, E., & Chamberlain, D. (2022). Measuring the influence of non-scientific features on citations. Scientometrics, 127, 4123–4137. https:// doi. org/ 10. 1007/ s11192- 022- 04421-7 Moed, H. F. (2010). Measuring contextual citation impact of scientific journals. Journal of Informetrics, 4(3), 265–277. https:// doi. org/ 10. 1016/j. joi. 2010. 01. 002 Momeni, F., Mayr, P., Fraser, N., & Peters, I. (2021). What happens when a journal converts to open access? A bibliometric analysis. Scientometrics, 126, 9811–9827. https:// doi. org/ 10. 1007/ s11192- 021- 03972-5 6609 Scientometrics (2023) 128:6589–6609 1 3 Nicolaisen, J., & Frandsen, T. F. (2008). The reference return ratio. Journal of Informetrics, 2, 128–135. https:// doi. org/ 10. 1016/j. joi. 2007. 12. 001 Patience, G. S., Patience, C. A., Blais, B., & Bertrand, F. (2017). Citation analysis of scientific categories. Heliyon, 3, e00300. https:// doi. org/ 10. 1016/j. heliy on. 2017. e00300 Shi, D., Rousseau, R., Yang, L., & Li, J. (2017). A journal’s impact factor is influenced by changes in publication delays of citing journals. Journal of the Association for Information Science and Technology, 68, 780–789. https:// doi. org/ 10. 1002/ asi. 23706 Trajkovski, V. A. (2018). Comparison Between electronic and printed journals. Journal for ReAttach Therapy and Developmental Diversities, 1, 1–6. https:// doi. org/ 10. 26407/ 2018J RTDD.1.1 Urlings, M. J. E., Duyx, B., Swaen, G. M. H., Bouter, L. M., & Zeegers, M. P. (2021). Citation bias and other determinants of citation in biomedical research: Findings from six citation networks. Journal of Clinical Epidemiology, 132, 71–78. https:// doi. org/ 10. 1016/j. jclin epi. 2020. 11. 019 Vadhera, A. S., Lee, J. S., Veloso, I. L., Khan, Z. A., Trasolini, N. A., Gursoy, S., Kunze, K. N., Chahla, J., & Verma, N. N. (2022). Open access articles garner increased social media attention and citation rates compared with subscription access research articles. An altmetrics-based analysis. The American Journal of Sports Medicine, 50, 3690–3697. https:// doi. org/ 10. 1177/ 03635 46522 11248 85 Vanderstraeten, R., & Vandermoere, F. (2021). Inequalities in the growth of Web of Science. Scientometrics, 126, 8635–8651. https:// doi. org/ 10. 1007/ s11192- 021- 04143-2 Vincent, A., & Ross, D. (2000). On evaluation of faculty research impact of citation analysis. The Journal of Applied Business Reseach, 16, 1–13. https:// doi. org/ 10. 19030/ jabr. v16i2. 2032 Wang, X. (2022) Characteristics analysis and evaluation of discourse leading for academic journals: perspectives from multiple integration of altmetrics indicators and evaluation methods, Library Hi Tech, in press. https:// doi. org/ 10. 1108/ LHT- 04- 2022- 0195 Yuret, T. (2018). Author-weighted impact factor and reference return ratio: Can we attain more equality among fields? Scientometrics, 116, 2097–2111. https:// doi. org/ 10. 1007/ s11192- 018- 2806-7 Zhang, Y. (1998). The impact of Internet-based electronic resources on formal scholarly communication in the area of library and information science: a citation analysis. Journal of Information Science, 24, 241–254. https:// doi. org/ 10. 1177/ 01655 51598 02400 403 Zhou, J., Feng, L., Cai, N., & Yang, J. (2020). Modeling and simulation analysis of journal impact factor dynamics based on submission and citation rules. Complexity, 2020, 3154619. https:// doi. org/ 10. 1155/ 2020/ 31546 19 Zitt, M., & Small, H. (2008). Modifying the journal impact factor by fractional citation weighting: The audience factor. Journal of the American Society for Information Science and Technology, 59(11), 1856– 1860. https:// doi. org/ 10. 1002/ asi. 20880 Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.