Factors Affecting the Number of Index-Terms of Journal Articles

Six factors were investigated to see their impacts on the number of index-terms of journal articles. The selected factors are length of articles, presence of abstracts, language of articles, date of indexing, Journal Impact Factor, and priority of journals for in-depth indexing.
Medical Subject Headings (MeSH) and its corresponding well known database “MEDLINE” were established to conduct this research. The data were analysed on the base of regression analysis.
1. There is a logarithmic relationship between the number of index terms per article and its pages. This relationship will occur if the articles are between one and twenty-one pages.
2. In general, journal articles with abstracts received almost two more terms than those included into MEDLINE without abstracts.
3. findability of non-English documents, such as articles written in German and indexed in an American-based database like MEDLINE, is less than that of English documents.
4. Journals with Impact Factors in the range from 0 to fifteen receive roughly the same number of index terms per page.
5. In an indexing system, different journals have more or less weight in their findability. Distribution of index terms per page has shown that there are three regions respectively with 2.3, 1.5, and 0.7 terms per page. In addition to these regions, few journals are the most favored ones and get more index term per page. “Nature”, “Science”, and “Transplant Proc” belong to such journals in MEDLINE.