Self-citations and impact factors of Croatian journals / E4
Twelve Croatian periodicals as referred in the Journal Citation Reports (JCR) published by Institute for Scientific Information (ISI) were analyzed with the emphasis on self-citations. Although it is expected from author to mention his/her earlier research in the new articles, the extent of self-citation should be reasonable. Especially referring to the previous work published in the same journal could potentially influence impact factor of the journal. In order to determinate the amount of self-citations among all other citations journal's self-citing rate as the percentage of citations given by the journal to itself and a journal's self-cited rate as percentage of citations received by the journal from itself was calculated for each journal.
Beside Tekstil, which have obvious unreliable data in the JCR database, journals with highest self-citing rate are Croatian Medical Journal, Društvena Istraživanja, Metalurgija and Collegium Antropologicum. Garfield noted that on the average for scientific literature journals, the self-citation rates had an average of approximately 20%. Almost 50% of Croatian journals have self-citing rate bellow that level.
Some of the journals listed in the JCR are not citing journals, but are cited-only journals. This is significant when comparing journals, because self-citations from cited-only journals are not included in the JCR data. For that reason it can be useful to calculate an impact factor that does not include self-citations. Impact factors without self-citations are significantly lower for most of Croatian Journals. Most of the journal will have without self-citations 30% decrease in impact factor. The biggest decrease is for Collegium Antropologicum and Metalurgija (assuming again the data for Tekstil are wrong).