- Impact factor as the name implies measures the impact of a particular journal on the readers, thereby making a particular journal more popular than other.
- Every author wants to publish his research in a journal which is read more and cited more often by others for further research; impact factor is a valuable tool to guide which journal to choose.
- Impact factor is used by librarians in selecting journals for library collection and it is also used to evaluate individual researcher or institute for academic promotion and funding allocation.
- The term impact factor was first coined by Eugene Garfield in the year 1955.His aim was to select journals for Science Citation Index (SCI) based on the quality rather than size of the journal. For eg., there are few smaller but important journals, they will never be selected for SCI if only number of citation or publication count is been done.
- A journal’s impact factor is decided by 2 factors: the numerator, which is the number of citations in the current year to any items published in a journal in the previous 2 years, and the denominator, which is the number of substantive articles (source items) published in same 2 years. It depicts the graph of the journal in a particular year.
For eg: Impact factor of X journal in year 2012=
Citation in 2012 for the articles published in 2011& 2012
Number of articles published in 2011&2012
- The impact factor is currently reported by the Institute for Scientific information (ISI) situated in Philadelphia in Journal Citation Report (JCR) published around July-august of every year. To make it uniform, all citations are normalized to take into account variables such as field, or discipline, and citation practices. Citation density and half life are other important variables.
- Although Impact factor substantially provide a good picture regarding the quality of the journal, it has some inherent flaws. Any journal published in English language and has open access policy have higher IF. Basic science journal rank higher than the clinical journal.
- IF can be manipulated by increasing number of review articles as they are cited more than other articles although original articles are adding new knowledge. IF although reflects journal quality, it has nothing to do with quality of articles or comparison of authors.
- In orthopaedics journals,Indian journal of orthopaedics has very low impact factor because of its recent inclusion in Science citation database.
- We can increase the IF of the journal by few ways. Time for whole process of submission, review and publication should be reduced. Review articles written by experts increase the IF of the journal. Case reports are not cited and it should be minimum in number.
- There are many studies done to evaluate IF as a validate measure of journal quality. Saha et al did a study to test its association with journal quality as rated by clinical practitioners and researchers and they found that a statistically significant correlation between impact factor and physicians rating of the journal quality.
- The correlation was higher for the research group than for the practitioner group.
- There are other indexes for journal quality like subscription rates and readership number but they are limited by the fact that they are mostly dependent on the journal cost, its ease of availability rather than true interest of the reader.
- Librarians having limited budget must choose appropriate journals for their institution. Impact factor helps them to choose by telling which journals are most frequently cited. However there is a problem here. Journal which have more newer original articles will have more IF than journal which focus on common day to day clinical problems which is more useful for clinical practitioner so this point should also be kept in mind.
- In conclusion, Impact factor despite having few shortcomings, it seems to be a valid and best tool for determining quality of medical journals, as judged by both clinical and researchers among all the currently available indices.
Dr Rajat Malot, MS, DNB. Fellow in Paediatric Orthopaedics
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