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  • General guides
  • Library information -data sheets
  • Guides for the Nelli portal and the TENTTU databases
  • Shelf classification
  • Instructions for the use of electronic materials
  • Guide to information searching
  • Journal impact factors
  • Citation management
  • Instructions for publishing
• User's brief guides
• Library rules and register descriptions

Journal impact factors

The order of superiority between scientific journals is often judged with impact factors (IF). The greater the impact factor of a journal the more citations have been made to the articles of the journal. Only a third of all scientific publications will ever be cited even once. Thus, the odds of an article in a top journal to be read and later cited are much higher than for an article in a less-known journal.

Impact factors can be used as support when selecting the forum of research publishing. It's perhaps worth mentioning in financial applications if earlier publications of the research in question have been published in journals with high impact factors.

Journal Citation Report (JCR)

Impact factors of journals are annually produced by International Scientific Institute (ISI). They are published in the Journal Citation Reports. The JCR can be accessed via the Nelli portal. It is one of the databases of the Web of Knowledge service provided by ISI.

The JCR is annually published in two parts:

• The Science Edition contains data of about 5,900 journals of medical, technological and natural sciences.
• The Social Sciences Edition contains data of about 1,700 journals of economical and social sciences.

Impact factors have been calculated mostly for Anglo-American journals. Medical journals and substantial journals of general science like Science and Nature have the greatest impact factors. Factors are high in fields of science where there is much research and of which research results are rapidly utilized in further research.

Calculating impact factors

Impact factors are calculated for each journal based on citations in the previous two-year period. It is done by dividing the amount of citations there have been to a journal's articles in a particular year by the amount of articles published during the two previous years.

Doubt about impact factors

Impact factors of ISI have been criticized for the following reasons:

• It is ambiguous what articles are incorporated; whether editorials, letters to editorial staff or reviews are considered as articles.
• Differences between the publishing practises of fields of science are not taken into account.
• The Accumulation time of references is too short.
• It has been proved that there have been distinct errors in calculating impact factors.
• Impact factors favour English which is the dominant langue in science.