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In Good Company…Now What About That Impact Factor?
Editorial
www.jpedhc.org
In Good Company.Now What About That Impact Factor? Martha K. Swartz, PhD, RN, CPNP, FAAN Last December, the Journal of Pediatric Health Care celebrated a major milestone when it was selected by Thomson Reuters (formerly Thomson Scientific) for inclusion in multiple abstracting and indexing services, including Journal Citation Reports. This achievement reflects the hard work and efforts of all those who have been and continue to be involved with the Journal, as well as a commitment by Thomson Reuter to expand their coverage of nursing journals. The key advantage of this step is that it will expand the dissemination of the Journal’s content throughout the entire health care community and thereby support our mission of promoting optimal health for children and families. We also will be provided with a set of standardized measures (as published annually in Journal Citation Reports) that are essentially markers of utilization, but as
measures of quality they should be interpreted and applied with caution. The first such measure is the impact factor (IF), which is said to be the most commonly used but also the most misunderstood of the three metrics (Amin & Mabe,
Last December, the Journal of Pediatric Health Care celebrated a major milestone when it was selected by Thomson Reuters.for inclusion in multiple abstracting and indexing services, including Journal Citation Reports. 2000). Simply put, the IF is a ratio of the number of times articles within an indexed journal were cited within a 2-year period divided by the number of articles that the journal published in that same time period. For example, if a journal is cited once, on average,
J Pediatr Health Care. (2009). 23, 141-142. 0891-5245/$36.00 Copyright Q 2009 by the National Association of Pediatric Nurse Practitioners. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.pedhc.2009.02.006
Journal of Pediatric Health Care
for each article published in that 2-year period, the IF would be one (1). In addition to the IF, the immediacy index of a journal is the number of citations a journal receives in a given year divided by the number of articles published. The cited half-life refers to the median age of articles that were cited in Journal Citation Reports. For example, if a journal’s cited halflife in 2008 was 5, this means that half of the citations from the journal were from the 5-year period 2004 to 2008 and the other half of the citations preceded 2004. Thus, the cited half-life is a measure of how long articles in a journal continue to be cited after publication. As a ratio of number of citations to number of articles published, the IF eliminates the bias of just looking at the total number of a journal’s citations, which would
favor journals that are larger, older, and more frequently published. However, the IF of a particular journal can be affected by a number of other factors, including the subject area of the journal, the types of articles published in the journal (such as letters, current research reports, or reviews), and the number of authors per article (which also often is related to the subject area). When comparing journals across disciplines, the absolute value of the IF is essentially meaningless because of the different May/June 2009
141
subject areas that journals address. For example, journals published in the field of microbiology generally have higher IFs than those published in oceanography. That doesn’t mean that any one discipline is more important. Even within a field (and nursing is a good example), there is a wide variety of subject areas that journals address, which then may make comparisons between journals based solely on an IF almost negligible. Similarly, within one professional field, variability exists among journals regarding the types of articles that are published. Articles that are essentially reviews tend to be cited more often than are research methods articles, yet both types of articles are essential for knowledge development within the profession. Because authors have a tendency to cite their own work, a strong correlation also
142
Volume 23
Number 3
exists between the average number of authors per paper and the average IF for a subject area. Of probably the greatest concern are situations in which the IF of a journal becomes a key consideration in decisions regarding appointments and promotions that affect persons in academia. The rule of thumb is that journals with IFs that differ by less than 25% should belong together in the same rank (Amin & Mabe, 2000). (This point is particularly important for nursing, because the overall range of IFs for nursing journals in 2007 was only two [2]). Because of such error, extending the importance of an IF for a journal to the authors of the articles published in that journal can be highly suspect. This practice also introduces a bias that may undervalue some types of scholarly research or productivity and distort
the total contribution a faculty member makes. The bottom line here is that the IF and other measures should not be perceived as gross estimations of a journal’s prestige. Rather, they should be interpreted within the larger context of the subject matter and the overall mission and format of a journal. In cases of faculty evaluation, there is probably no substitute for informed peer review. And while journals are important regarding their impact on the profession, I think we would all agree that of greater importance is the positive impact we have on the health of children and families through our daily practice, teaching, research, and advocacy. REFERENCE Amin, M., & Mabe, M. (2000). Impact factors: Use and abuse. Perspectives in Publishing, 1, 2-6.
Journal of Pediatric Health Care
www.jpedhc.org
In Good Company.Now What About That Impact Factor? Martha K. Swartz, PhD, RN, CPNP, FAAN Last December, the Journal of Pediatric Health Care celebrated a major milestone when it was selected by Thomson Reuters (formerly Thomson Scientific) for inclusion in multiple abstracting and indexing services, including Journal Citation Reports. This achievement reflects the hard work and efforts of all those who have been and continue to be involved with the Journal, as well as a commitment by Thomson Reuter to expand their coverage of nursing journals. The key advantage of this step is that it will expand the dissemination of the Journal’s content throughout the entire health care community and thereby support our mission of promoting optimal health for children and families. We also will be provided with a set of standardized measures (as published annually in Journal Citation Reports) that are essentially markers of utilization, but as
measures of quality they should be interpreted and applied with caution. The first such measure is the impact factor (IF), which is said to be the most commonly used but also the most misunderstood of the three metrics (Amin & Mabe,
Last December, the Journal of Pediatric Health Care celebrated a major milestone when it was selected by Thomson Reuters.for inclusion in multiple abstracting and indexing services, including Journal Citation Reports. 2000). Simply put, the IF is a ratio of the number of times articles within an indexed journal were cited within a 2-year period divided by the number of articles that the journal published in that same time period. For example, if a journal is cited once, on average,
J Pediatr Health Care. (2009). 23, 141-142. 0891-5245/$36.00 Copyright Q 2009 by the National Association of Pediatric Nurse Practitioners. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.pedhc.2009.02.006
Journal of Pediatric Health Care
for each article published in that 2-year period, the IF would be one (1). In addition to the IF, the immediacy index of a journal is the number of citations a journal receives in a given year divided by the number of articles published. The cited half-life refers to the median age of articles that were cited in Journal Citation Reports. For example, if a journal’s cited halflife in 2008 was 5, this means that half of the citations from the journal were from the 5-year period 2004 to 2008 and the other half of the citations preceded 2004. Thus, the cited half-life is a measure of how long articles in a journal continue to be cited after publication. As a ratio of number of citations to number of articles published, the IF eliminates the bias of just looking at the total number of a journal’s citations, which would
favor journals that are larger, older, and more frequently published. However, the IF of a particular journal can be affected by a number of other factors, including the subject area of the journal, the types of articles published in the journal (such as letters, current research reports, or reviews), and the number of authors per article (which also often is related to the subject area). When comparing journals across disciplines, the absolute value of the IF is essentially meaningless because of the different May/June 2009
141
subject areas that journals address. For example, journals published in the field of microbiology generally have higher IFs than those published in oceanography. That doesn’t mean that any one discipline is more important. Even within a field (and nursing is a good example), there is a wide variety of subject areas that journals address, which then may make comparisons between journals based solely on an IF almost negligible. Similarly, within one professional field, variability exists among journals regarding the types of articles that are published. Articles that are essentially reviews tend to be cited more often than are research methods articles, yet both types of articles are essential for knowledge development within the profession. Because authors have a tendency to cite their own work, a strong correlation also
142
Volume 23
Number 3
exists between the average number of authors per paper and the average IF for a subject area. Of probably the greatest concern are situations in which the IF of a journal becomes a key consideration in decisions regarding appointments and promotions that affect persons in academia. The rule of thumb is that journals with IFs that differ by less than 25% should belong together in the same rank (Amin & Mabe, 2000). (This point is particularly important for nursing, because the overall range of IFs for nursing journals in 2007 was only two [2]). Because of such error, extending the importance of an IF for a journal to the authors of the articles published in that journal can be highly suspect. This practice also introduces a bias that may undervalue some types of scholarly research or productivity and distort
the total contribution a faculty member makes. The bottom line here is that the IF and other measures should not be perceived as gross estimations of a journal’s prestige. Rather, they should be interpreted within the larger context of the subject matter and the overall mission and format of a journal. In cases of faculty evaluation, there is probably no substitute for informed peer review. And while journals are important regarding their impact on the profession, I think we would all agree that of greater importance is the positive impact we have on the health of children and families through our daily practice, teaching, research, and advocacy. REFERENCE Amin, M., & Mabe, M. (2000). Impact factors: Use and abuse. Perspectives in Publishing, 1, 2-6.
Journal of Pediatric Health Care