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    17.5 Age of Useful Articles

    Table 17.4 shows calculated summary data for the most frequently used articles in each of the 15 JSTOR clusters. The purpose of this assessment was to take an initial snapshot of the relative value of older literature in each of our JSTOR fields. The chart was assembled by first collecting the number of article views from the JSTOR database, ranking the articles in order from most-often viewed to least viewed, and as in the case of the analysis above, pulling out the ten most frequently used articles. We know the year of publication for each article, so we were able to calculate the average age of the top ten articles for each title. We then averaged these data across each discipline to provide an estimate of the average age of the most-used articles in each field. When evaluated in this way, it was apparent that some older articles have truly lasting value, that in most of the JSTOR fields, older articles were well-represented among the "top ten", and that the value of older material seems to vary with the discipline.

    Again, to use the field of economics as an example, a surprising number of older articles have emerged as the most heavily used. The average age of the articles in the top ten most printed and viewed articles in the economics cluster is 13 years. This is rather surprising, as our expectation before starting JSTOR would have been that usage of economics journals would be much more focused on more recent issues.

    Table 17.4: Summary data for the most frequently used articles in each of the 15 JSTOR clusters.
    Number of Titles Num. of Views from Top 10 Share of Top 10 Views Avg. First Year of Publication Avg. Most Recent JSTOR Year Avg. Age in years of Top 10 Articles
    African American Studies 7 16,637 4% 1959 1996 3
    Anthropology 6 12,301 3% 1954 1994 4
    Asian Studies 4 5,433 1% 1936 1994 11
    Ecology 6 19,293 5% 1943 1996 11
    Economics 13 87,711 22% 1936 1994 13
    Education 4 13,153 3% 1946 1995 11
    Finance 5 13,201 3% 1958 1995 10
    History 15 58,365 15% 1934 1995 12
    Literature 11 23,992 6% 1946 1995 7
    Mathematics 11 7,344 2% 1932 1994 32
    Philosophy 10 16,538 4% 1931 1994 16
    Political Science 9 52,201 13% 1933 1995 8
    Population/Demography 8 15,808 4% 1965 1995 5
    Sociology 9 41,387 11% 1945 1994 6
    Statistics 11 8,480 2% 1936 1994 9

    An even more dramatic example is Mathematics, where the average age of the most used articles in the field is 32 years! This result is consistent with what mathematicians have told us about their field; that is, that older mathematics literature remains valuable. (Mathematicians are some of the most enthusiastic supporters of JSTOR and regularly urge us to include more mathematics titles). However, it is worth pointing out that usage of the mathematics cluster in JSTOR has lagged behind usage in other fields. With the long runs of its 11 journals, as a cluster mathematics has the highest number of pages in JSTOR, and yet usage of the mathematics cluster represents just 3.3% of total usage. One reason for making this point here is that there simply is not enough data to make too much of the average length of the article in mathematics. With a small number of total accesses for the field, the actions of a few people can sway the data significantly. As mentioned earlier, one has to be careful about drawing conclusions from the data.

    Nevertheless, the apparent contradiction between the qualitative value of JSTOR to mathematicians and the usage of the mathematics journals in JSTOR dramatically illustrates an extremely important point. One must define clearly what one means by "value". Usage does not necessarily equate to value in the research sense. Older articles may be absolutely vital to the continuation of high-quality scholarship and research in the field, but that may not lead to extensive use. Increasingly, one hears that libraries are planning to use electronic usage data to help make subscription decisions. If relied upon exclusively, this could prove to be a very dangerous tool, making it more difficult for lesser-used but valuable research journals to survive. Other measures, like citation data, need to be incorporated as well. The nature of these data will also change with the availability of electronic resources. One wonders, for example, if the number of citations to older articles in JSTOR will increase as the older articles become more conveniently accessible. This possibility is worth monitoring, but with the understanding that it will take years before changes in scholars' behavior will manifest itself in the citation data. Understanding the nature of a field and the way that research materials are used in the field is essential before making selection and cancellation decisions. It is our hope that, over the long run, JSTOR can contribution to this kind of understanding.