Reading factor: a new bibliometric criterion for managing digital libraries.

Although various methods are used to evaluate biomedical journals, there is no standard reference for fully assessing the impact of a journal in clinical medicine [1]. The utility or influence of a given paper on diagnosis or therapeutics has not been clearly defined. This study presents a novel mode of evaluation. In the research literature, an acknowledged criterion of value is the degree of influence on secondary papers. A citation by other articles is accepted as a fair estimate of the value or importance of a publication [2]. The impact factor (IF), published in the Science Citation Index (SCI) Journal Citation Reports (JCR), is based on a bibliometric analysis of science journals in the ISI database [3]. Although it has been criticized [4–8], IF is the most common bibliometric criterion for ranking and evaluating biomedical journals [9]. As IF represents, by its nature, an indirect criterion, a direct measure of journal use should be considered. The number of times a publication is consulted is an objective criterion of use. The recent availability of digital versions of major biomedical journals presents an opportunity to directly measure their electronic consultation rates. This paper describes a way to measure the electronic consultation rate that the authors have termed the reading factor (RF), in direct correlation to the impact factor. RF measures the interest in a journal within the limit of a given readership. It is a direct measurement of journal use that is related to both clinical medicine and library or information science. Results of the observed distribution of RF for the year 1998 and IF for 1997 are shown in Table 1. The Rouen University Hospital (RUH) medical digital library was created in 1997. This library allows all 304 RUH senior physicians to access MEDLINE, forty-six electronic full-text journals, and some selected electronic books from their offices at no charge [10]. Table 1 Impact factor (IF) versus reading factor (RF) based on forty-six biomedical journals METHODS Electronic full text has been provided by Ovid®, a commercial company, via the RUH intranet since 1997. These journals are offered as packages known as Biomedical Collections volumes I, II, and III, which contain fifteen, fifteen, and sixteen journals, respectively. They have been available at RUH since June, September, and December 1997, respectively. The journals in each package are selected by Ovid based on the coverage of major biomedical specialties, journal impact factors, and agreements with publishers. Table 1 includes all forty-six journals. The number of electronic consultations is incremented each time end users click on a hyperlink to open individual publications. To obtain a standardized measure of the electronic-consultation rate and to avoid an institution-size effect, the RF is defined as the ratio between the number of electronic consultations of an individual journal and the mean number of electronic consultations of all the journals studied or as the following equation: where Cj is the number of electronic consultations of journal j, and N is the total number of journals available in the database. The normalization of the reading factor has also been performed, because ISI journal impact factor is a similarly normalized value. Thus, a value of 1 represents an average consultation rate, while a value greater than 1 represents a higher-than-average consultation rate. The normalized reading factor is defined (data not shown) as the ratio between the number of electronic consultations and the number of articles of a particular journal.