Concentration of the most-cited papers in the scientific literature: analysis of journal ecosystems.
BACKGROUND: A minority of scientific journals publishes the majority of scientific papers and receives the majority of citations. The extent of concentration of the most influential articles is less well known. METHODS/PRINCIPAL FINDINGS: The 100 most-cited papers in the last decade in each of 21 scientific fields were analyzed; fields were considered as ecosystems and their "species" (journal) diversity was evaluated. Only 9% of journals in Journal Citation Reports had published at least one such paper. Among this 9%, half of them had published only one such paper. The number of journals that had published a larger number of most-cited papers decreased exponentially according to a Lotka law. Except for three scientific fields, six journals accounted for 53 to 94 of the 100 most-cited papers in their field. With increasing average number of citations per paper (citation density) in a scientific field, concentration of the most-cited papers in a few journals became even more prominent (p<0.001). Concentration was unrelated to the number of papers published or number of journals available in a scientific field. Multidisciplinary journals accounted for 24% of all most-cited papers, with large variability across fields. The concentration of most-cited papers in multidisciplinary journals was most prominent in fields with high citation density (correlation coefficient 0.70, p<0.001). Multidisciplinary journals had published fewer than eight of the 100 most-cited papers in eight scientific fields (none in two fields). Journals concentrating most-cited original articles often differed from those concentrating most-cited reviews. The concentration of the most-influential papers was stronger than the already prominent concentration of papers published and citations received. CONCLUSIONS: Despite a plethora of available journals, the most influential papers are extremely concentrated in few journals, especially in fields with high citation density. Existing multidisciplinary journals publish selectively most-cited papers from fields with high citation density. (+info
Sharing detailed research data is associated with increased citation rate.
BACKGROUND: Sharing research data provides benefit to the general scientific community, but the benefit is less obvious for the investigator who makes his or her data available. PRINCIPAL FINDINGS: We examined the citation history of 85 cancer microarray clinical trial publications with respect to the availability of their data. The 48% of trials with publicly available microarray data received 85% of the aggregate citations. Publicly available data was significantly (p = 0.006) associated with a 69% increase in citations, independently of journal impact factor, date of publication, and author country of origin using linear regression. SIGNIFICANCE: This correlation between publicly available data and increased literature impact may further motivate investigators to share their detailed research data. (+info
Characteristics associated with citation rate of the medical literature.
BACKGROUND: The citation rate for articles is viewed as a measure of their importance and impact; however, little is known about what features of articles are associated with higher citation rate. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a cohort study of all original articles, regardless of study methodology, published in the Lancet, JAMA, and New England Journal of Medicine, from October 1, 1999 to March 31, 2000. We identified 328 articles. Two blinded, independent reviewers extracted, in duplicate, nine variables from each article, which were analyzed in both univariable and multivariable linear least-squares regression models for their association with the annual rate of citations received by the article since publication. A two-way interaction between industry funding and an industry-favoring result was tested and found to be significant (p = 0.02). In our adjusted analysis, the presence of industry funding and an industry-favoring result was associated with an increase in annual citation rate of 25.7 (95% confidence interval, 8.5 to 42.8) compared to the absence of both industry funding and industry-favoring results. Higher annual rates of citation were also associated with articles dealing with cardiovascular medicine (13.3 more; 95% confidence interval, 3.9 to 22.3) and oncology (12.6 more; 95% confidence interval, 1.2 to 24.0), articles with group authorship (11.1 more; 95% confidence interval, 2.7 to 19.5), larger sample size and journal of publication. CONCLUSIONS/SIGNIFICANCE: Large trials, with group authorship, industry-funded, with industry-favoring results, in oncology or cardiology were associated with greater subsequent citations. (+info
Citation analysis of the Croatian Medical Journal: the first 15 years.
The Croatian Medical Journal (CMJ) is a bimonthly scientific journal, that publishes mostly original articles. It is indexed in the Index Medicus/MEDLINE, Current Contents/Clinical Medicine, and the Science Citation Index Expanded. Since the CMJ's 15th anniversary in 2007, our aim has been to assess the importance of the Journal through its impact factor (IF) and immediacy index, with a particular focus placed on the proportion of self-citations. According the Web of Knowledge database, the current official IF for the CMJ is 0.825, ranking it 62nd out of 103 journals within the Thomson Scientific category "Medicine - General and Internal." The exclusion of self-citations resulted in a small decrease in the journal's rank - to 66th place. According to the Web of Science database, the predicted CMJ IF in 2007 is between 1.024 and 1.125, showing a clear increase. The immediacy index of the CMJ is continuously low, with a high contribution of self-citations, implying that articles published in the CMJ require more time to be cited, and that their topics are of particular interest to the journal's readers and contributors. Self-citations contributed significantly to the IF in the first few years after the journal was established. The proportion of independent citations progressively increased, and of all the citations included in the IF in 2007, almost 70% were fully independent. Some of these citations were from articles published in journals with IF higher than 5. Taken together, our data suggest that the CMJ has significantly improved its citation ratings during the last 15 years, confirming that a quality-oriented editorial policy in a small peripheral journal may result in a truly increased international visibility. (+info
Factors influencing editors' decision on acceptance or rejection of manuscripts: the authors' perspective.
Journal impact factor and its importance for AFP.
BACKGROUND: In 2008, Australian Family Physician (AFP) was accepted on the list of journals listed in Science Citation Index Expanded and, thus, will generate an impact factor over the next 2 years. Impact factor is important to authors from research and academic backgrounds and will make AFP an increasingly attractive journal in which to publish. AIM: To describe the impact factor, its method of calculation, and its flaws. DISCUSSION: Impact factor is the number of a journal's cited research papers divided by the total number of citable papers it has published. It is distorted by several different factors: sub-discipline, region, basic versus applied research, and whether the journal editor deliberately tries to strategically increase their impact factor. CONCLUSION: Impact factor is an oversimplified single measure of 'impact', which may underestimate the contribution of the AFP to society. However, no accepted alternative metric currently exists. (+info
Sometimes the impact factor outshines the H index.
Research productivity of members of IADR Behavioral Sciences and Health Services Research Group: relationship to professional and personal factors.
This report describes the research productivity of the members of the International Association for Dental Research (IADR) Behavioral Sciences and Health Services Research Group and examines personal and professional factors related to greater productivity. The findings from previous studies suggested there might be gender discrimination in opportunities for women faculty. Members on the active membership list for this IADR group were surveyed by email. Most were dentists, and three-quarters had external funding for their research. The primary outcome measure was the number of self-reported published articles in PubMed in the preceding twenty-four months. The mean number of these publications was 4.9 (SD=5.1). Gender and time in research were the best predictors of research productivity of this population. There was no difference in time for research between the men and women in this study. Controlling for gender, the best single predictor of research productivity remained percent time spent in research. Overall, the members of the IADR group spent almost three times as much time in research and were more than twice as productive as faculty members as a whole as described in earlier studies. In view of the current emphasis in many countries on addressing the social and behavioral determinants of oral health disparities, the productivity of this area of dental research is very important. Trends toward clinically oriented, non-research-intensive dental schools in the United States and reductions in time and funding available to conduct research should be of concern. (+info