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Predictors of citation rate
Annals of Epidemiology 26 (2016) 160
Contents lists available at ScienceDirect
Annals of Epidemiology journal homepage: www.annalsofepidemiology.org
Letter to the Editor
Predictors of citation rate Prof. Ruano-Ravina et al. [1] analyzed the determinants of citations in a Spanish journal of public health. They found that articles selected for a press release and the number of articles published previously by the corresponding author predict a higher rate of citations. However, they did not control their findings for known confounding factors. Moreover, for counting the number of citations of articles published in local journals such as a Spanish journal of public health, citations of the articles in journals without impact factors should also be considered. Thus, Scopus identifies more citations than Web of Science for a Spanish journal of public health. Currently, Scopus contains more than 53 million publications, and Web of Science has more than 40 million publications. Only a small percentage of readers search news archives or look at the number of articles published by the corresponding author to cite an article. Citing a research article is influenced by journal impact factor, study design, sample size, size of effect and statistical significance, topic, and language [2e4]. Review articles and articles published in English are more often cited than original studies or articles published in a local language. Articles with statistically significant results are cited more frequently than others [3,5]. Owing to low statistical power, Ruano-Ravina et al. [1] did not find a statistically significant association between article type or language and a number of citations. For observational studies, a prospective cohort design can be cited more than a cross sectional design. A press release and the number of articles published previously by the corresponding author are markers of higher study quality. Ruano-Ravina et al. [1] found a weak association between the number of articles published by the corresponding author during the preceding 5 years and number of citations. The effect size was 10% (95% confidence
DOI of original article: 10.1016/j.annepidem.2015.09.010. The author declares that he has no conflict of interest.
1047-2797/Ó 2016 Elsevier Inc. All rights reserved.
interval: 0%e16%) for cited versus uncited articles and 5% (95% confidence interval: 1.5% to 15.4%) for three or more citations versus one to two citations for each five publications increase in the number of articles published by the corresponding author during the preceding 5 years using odds ratio as an effect size. The corresponding figures will be about 5% and 2.5% using a risk ratio. The association between the number of articles published previously by the corresponding author or a press release and citation rate may disappear after controlling for study design, sample size and effect size, or statistical significance of the results. Rahman Shiri, MD, PhD Finnish Institute of Occupational Health Helsinki, Finland http://dx.doi.org/10.1016/j.annepidem.2015.11.009
References [1] Ruano-Ravina A, Álvarez-Dardet C, Domínguez-Berjón MF, Fernández E, García AM, Borrell C. Externalities and article citations: experience of a national public health journal (Gaceta Sanitaria). Ann Epidemiol 2016;26:81e4. [2] Willis DL, Bahler CD, Neuberger MM, Dahm P. Predictors of citations in the urological literature. BJU Int 2011;107:1876e80. [3] Nieminen P, Rucker G, Miettunen J, Carpenter J, Schumacher M. Statistically significant papers in psychiatry were cited more often than others. J Clin Epidemiol 2007;60:939e46. [4] Callaham M, Wears RL, Weber E. Journal prestige, publication bias, and other characteristics associated with citation of published studies in peer-reviewed journals. JAMA 2002;287:2847e50. [5] Jannot AS, Agoritsas T, Gayet-Ageron A, Perneger TV. Citation bias favoring statistically significant studies was present in medical research. J Clin Epidemiol 2013;66:296e301.
Contents lists available at ScienceDirect
Annals of Epidemiology journal homepage: www.annalsofepidemiology.org
Letter to the Editor
Predictors of citation rate Prof. Ruano-Ravina et al. [1] analyzed the determinants of citations in a Spanish journal of public health. They found that articles selected for a press release and the number of articles published previously by the corresponding author predict a higher rate of citations. However, they did not control their findings for known confounding factors. Moreover, for counting the number of citations of articles published in local journals such as a Spanish journal of public health, citations of the articles in journals without impact factors should also be considered. Thus, Scopus identifies more citations than Web of Science for a Spanish journal of public health. Currently, Scopus contains more than 53 million publications, and Web of Science has more than 40 million publications. Only a small percentage of readers search news archives or look at the number of articles published by the corresponding author to cite an article. Citing a research article is influenced by journal impact factor, study design, sample size, size of effect and statistical significance, topic, and language [2e4]. Review articles and articles published in English are more often cited than original studies or articles published in a local language. Articles with statistically significant results are cited more frequently than others [3,5]. Owing to low statistical power, Ruano-Ravina et al. [1] did not find a statistically significant association between article type or language and a number of citations. For observational studies, a prospective cohort design can be cited more than a cross sectional design. A press release and the number of articles published previously by the corresponding author are markers of higher study quality. Ruano-Ravina et al. [1] found a weak association between the number of articles published by the corresponding author during the preceding 5 years and number of citations. The effect size was 10% (95% confidence
DOI of original article: 10.1016/j.annepidem.2015.09.010. The author declares that he has no conflict of interest.
1047-2797/Ó 2016 Elsevier Inc. All rights reserved.
interval: 0%e16%) for cited versus uncited articles and 5% (95% confidence interval: 1.5% to 15.4%) for three or more citations versus one to two citations for each five publications increase in the number of articles published by the corresponding author during the preceding 5 years using odds ratio as an effect size. The corresponding figures will be about 5% and 2.5% using a risk ratio. The association between the number of articles published previously by the corresponding author or a press release and citation rate may disappear after controlling for study design, sample size and effect size, or statistical significance of the results. Rahman Shiri, MD, PhD Finnish Institute of Occupational Health Helsinki, Finland http://dx.doi.org/10.1016/j.annepidem.2015.11.009
References [1] Ruano-Ravina A, Álvarez-Dardet C, Domínguez-Berjón MF, Fernández E, García AM, Borrell C. Externalities and article citations: experience of a national public health journal (Gaceta Sanitaria). Ann Epidemiol 2016;26:81e4. [2] Willis DL, Bahler CD, Neuberger MM, Dahm P. Predictors of citations in the urological literature. BJU Int 2011;107:1876e80. [3] Nieminen P, Rucker G, Miettunen J, Carpenter J, Schumacher M. Statistically significant papers in psychiatry were cited more often than others. J Clin Epidemiol 2007;60:939e46. [4] Callaham M, Wears RL, Weber E. Journal prestige, publication bias, and other characteristics associated with citation of published studies in peer-reviewed journals. JAMA 2002;287:2847e50. [5] Jannot AS, Agoritsas T, Gayet-Ageron A, Perneger TV. Citation bias favoring statistically significant studies was present in medical research. J Clin Epidemiol 2013;66:296e301.