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17. Revitalizing Older Published Literature: Preliminary Lessons from the Use of JSTOR[†]
Perhaps it would be best to begin this chapter by stating explicitly what it is not. This chapter does not present a scientific study. It does not purport to present evidence that will lead the reader to a carefully argued conclusion. Rather, it is an attempt to highlight some of the questions that usage of the JSTOR database is enabling us to ask and to begin to assess whether there are answers that will prove interesting or valuable to the scholarly community. At this stage, and with the relatively small amount of data and minimal degree of analysis that has been conducted, this report should be regarded as highly preliminary.
JSTOR began as a research project sponsored by The Andrew W. Mellon Foundation at the University of Michigan. Its original objective was to test whether the digitized versions of older research journals might serve as a substitute for the paper versions, thereby offering libraries the possibility of long-term savings in shelving and archiving costs while simultaneously improving their usability. A pilot database was created that included the back runs of ten journals — five in history and five in economics — and access was made available at five liberal arts colleges and the University of Michigan. By the summer of 1995, it was apparent that the concept held great promise, and JSTOR was established as an independent not-for-profit organization. JSTOR was founded to carry on the original objective stated above, but with the added charge that it develop an economic model that would allow it to become self-sustaining.
The JSTOR Phase I database now includes the backfiles of 117 journal titles (see Table 17.1) from 15 academic disciplines, a collection numbering nearly 5,000,000 pages. As of March 2000, more than 650 academic institutions from 30 countries were participants in this collaborative enterprise, with approximately 100 colleges and universities having had access to the database since early 1997. The amount of usage of the resource and its growth rate have been surprising. In 1999, over 1.4 million articles were printed from the JSTOR database, over 4 million searches were performed, and users accessed the database more than 17 million times.
Figure 17.1 illustrates the growth in the total number of accesses since the database was first made available.
When JSTOR was established, many people questioned the wisdom of converting journal backfiles. With comparatively little use of these materials in paper form, one could not help but wonder whether there would be sufficient interest in gaining access to the resource to warrant the substantial investments that would have to be made to create it. It is clear that it would not have been possible even to conceive of pursuing a project like JSTOR without the interest of the Mellon Foundation. Through its grant-making, the Foundation provided the financial resources necessary to establish the technological infrastructure required to create the database. Perhaps more importantly, however, the Mellon Foundation contributed staff time, most notably that of its President, William G. Bowen, to launch the enterprise.
The investments of the Mellon Foundation have made it possible for JSTOR to pursue and begin to fulfill its important not-for-profit mission, one component of which is to enhance the accessibility of little-used and inconvenient-to-retrieve journal literature. Another primary component of JSTOR's mission is to act as a trusted archive for the material under its care. This part of JSTOR's mission is reflected in the number of articles in the database that are not being heavily used today, but which may someday be a critical component of a new line of argument for an important paper or research article.
Early analysis of JSTOR's usage data allows us to begin to ask questions about how scholars and students use older literature in electronic form. Do scholars and students make use of the older articles? Are the materials being used more now than they were in paper format only? Can these data provide guidance about what material should be digitized? Does the usefulness of the older literature vary by academic discipline? These are some of the questions that we hope JSTOR will answer over the long run.
17.1 Comparing JSTOR Use to the Usage of the Journals in Paper Format
As part of the original JSTOR pilot project, an effort was made to collect circulation and usage information for the ten pilot journals. The hope was that the data would serve as a benchmark for comparison purposes. Unfortunately, it was not easy to collect reliable data. Since many of the journals were available in open stacks, it was not possible to obtain accurate circulation figures (although some circulation data were obtained from the University Reserves office at the University of Michigan Library). Instead of regular circulation data, two counting methods were employed to obtain information about use of these journals. First, slips of paper were placed in each journal volume with a request that a user mark when they had used the volume. Signs were also placed in the area of the journals to instruct users of the survey being conducted. Second, staff at the library pilot sites were instructed to check the shelves each business day for several months and make note of which volumes were not on the shelves. The volumes not on the shelves were counted as having been used.
Also, only the journal volumes housed on the main library shelves at the participating pilot libraries were included in this work. Usage of the paper volumes in faculty offices or in departmental libraries was not captured. Because of the lack of a controlled environment and the relatively narrow scope of this study, one must be careful about conclusions drawn when comparing these data to site license access to JSTOR at the institutions.
It does appear, however, that the electronic articles in JSTOR are being used much more frequently than they were used in the paper form. The paper usage data was collected over varying lengths of times at the five institutions that returned data, but a minimum of three months of information was collected. There were a total of 692 uses of the ten journals at the five test sites over the course of the entire survey period. Usage of the same journals in JSTOR at the same five sites for the months of September, October and November of 1999 yields a total of more than 7,696 article views. In addition, although there is presumably substantial overlap in articles viewed and those printed, 4,885 articles were printed — a total of 12,581 views and prints during the three month time period. When compared to the 692 uses in the benchmarking survey, it would seem that the convenience of having electronic access is facilitating greatly increased use of the material.
Another way to assess whether usage of the older journals in electronic form is greater than in paper is by evaluating the growth in usage. As Andrew Odlyzko points out in Chapter 2, growth rates may matter more than absolute numbers. It is rather unlikely that the usage of older articles in paper form was growing at measurable rates. That contrasts markedly with usage of JSTOR (as well as other resources discussed in this book). Growth in the aggregate use of the JSTOR database has increased dramatically in the period since 1997 when it first became available. Table 17.2 below shows the total accesses to the database by institution type. Total accesses to all content in the database increased 4.4 times from 1997 to 1998 and 3 times from 1998 to 1999.
|JSTOR Class||Accesses 1997||Accesses 1998||1997-1998 Growth Factor||Accesses 1999||1998-1999 Growth Factor|
Because some of the growth in aggregate usage of JSTOR is a result of new institutions signing up for the database during this time period, we have compiled usage figures at institutions that had JSTOR installed prior to April 1, 1997. Aggregate accesses at these institutions increased by a factor of 3.4 times from 1997 to 1998 and by a factor of 2.5 times from 1998 to 1999. The cumulative growth of usage over the three-year time period at existing sites is 740%!
As one contemplates this impressive growth in JSTOR usage, it is perhaps valuable to note that JSTOR is available "for free" to end users. Libraries have paid participation site license fees that allow authorized users (faculty, staff, and students) to make unlimited use of the resource. For the most part, authentication is handled by IP address, thereby making the authentication process virtually invisible. This unfettered access contributes to the rapid growth in use of the resource; it is consistent with the kind of growth one is seeing in other resources available on the World Wide Web. This picture might be very different indeed if JSTOR were charging either users or libraries based on usage.
17.2 The Interdisciplinary Appeal of JSTOR
An additional variable that is likely to be a contributing factor to the increasing use of JSTOR is the addition of new content. Since 1997 JSTOR has been digitizing new journals and making them available to participating institutions. Content in new academic disciplines introduces new scholars and students to the resource. Additional content in existing fields broadens the appeal of the resource within that discipline.
As the resource has grown, it is evident that the cross-title and interdisciplinary appeal of the resource has grown as well. Pulling from the search logs of a recent week of JSTOR use reveals that approximately 68,000 searches were conducted. Of these, just under 62,000 (91%) specified more than one title. Because JSTOR offers the option to search by cluster (pre-defined discipline-specific collections), it is convenient for users to search across journals in a single discipline. Approximately 58,000 searches specified clusters. Of those cluster searches, 69% specified more than one cluster. This is quite significant because the JSTOR interface does not offer an option to select all clusters. Judging from this behavior, the ability to search across disciplines is important to users.
17.3 Nature and Distribution of Use
There are a total of 831,087 articles in the JSTOR database. Our use of the term "article" may be a bit misleading in that it refers to all items that are indexed as an item for retrieval. Full-length articles are a sub-set of this total, of which there are presently 356,978. Other "articles" are items like book reviews, letters to the editor, membership lists, and the like.
The distribution of the use of JSTOR is interesting because it speaks to the extent to which JSTOR functions as an archive. Many libraries, particularly research and academic libraries, have a mission to collect not only that material that is likely to be used today, but also to collect and care for that information which may be valuable in the future. JSTOR has surprised us in the extent and degree that it has been used, but there is something to be learned also from what has not been used.
After three years, 430,429 different articles have been viewed, representing 51.8% of all articles in the database. (Many of these articles have been viewed multiple times; the figure above relates to whether the article has ever been viewed.) 248,683 articles have been printed, representing 29.9% of all articles.
The complement to the statement above is that nearly half of the articles in the JSTOR database have never been viewed or printed. Will they ever be used? We do not know. Further, we find the distribution of use among the articles to be rather concentrated. Figure 17.2 presents the number of article views accounted for by the top n articles. For example, the top 100 articles viewed represent 112,072, or 2% of the total article views. The top 10,000 most viewed articles were viewed 1,987,982 times, or 36% of the total. And the top 100,000 most viewed articles were viewed 4,613,610 times, or 82 % of the total. This last figure means that 12% of the articles accounted for 82% of the views. This high concentration may be somewhat misleading because our count of total "articles", as mentioned before, includes all items in the database, such as reviews, and front matter and back matter, not just full length articles. Since it is natural that many of these items may never be viewed or cited, but are included in JSTOR to present the complete and comprehensive digital version of the originally published journal, this level of concentration probably should be expected. In any event, it is not a concern to JSTOR since its mission is to serve as an archive and not to make its decisions on preservation of content based on the amount of use of the various articles contained in the database.
17.4 Selection Criteria
Since it is generally accepted that it will not be possible to digitize all journals that have ever been published, an important question for any digitization project is how to select the retrospective content to be made available electronically. In JSTOR a variety of factors are taken into consideration in the selection process, including surveys of faculty and library professionals in the field in question, library subscription levels, citation impact factor measures, and length of the run, among other things.
Looking at JSTOR usage at the article level, it is evident that citations should not be used as the sole factor in determining what content should be digitized. To test the question of whether citation or citation frequency correlates with database usage, we conducted a preliminary analysis on use of particular articles in JSTOR. First, we identified the top ten most frequently used articles for each of the 117 journals in the database. We then looked up their citation data using ISI Social Science Citations. What we found was that usage and citation data were not correlated. For the purpose of illustrating the point, Table 17.3 displays an abbreviated version of the data we collected. Shown below are the top three articles in terms of JSTOR use since 1997 (through March 20, 2000) for three Economics titles. The number of citations to each article in the period from 1997 to 1999 is displayed, as are the average number of citations to each article for the period from 1972 through 1999.
|Journal Title||Number of Times Cited||Average cites/year||JSTOR views||Year of Publication|
|American Economic Review|
|Quarterly Journal of Economics|
|Journal of Political Economy|
Citations do not appear to provide anything like a complete picture of the potential usefulness of a journal article. The most notable example of this point is the number one article for the Journal of Political Economy. Even though this 1973 article has rarely been cited (4 times between 1997 and 1999) and only an average of .5 times per year between 1972 and 1999, it has emerged as the most often-used article from that journal. This article has been viewed 1,895 times and printed 1,402 times during the period that it has been accessible in JSTOR. What this example reveals is not only that citation data may not be the most useful measure for determining what should be digitized, but also that citations focus on what might be called the "reference" or "documentation" value of an article, not its usefulness defined more broadly. Articles with four citations may end up, for a variety of reasons, being the most used. Or, alternatively, highly cited articles may not be used very often at all. This is a factor to keep in mind when selecting content for digitization initiatives.
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.
|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|
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.
This paper provides a brief overview of preliminary information emerging from JSTOR usage data. As JSTOR usage increases, more interesting questions about the way that retrospective electronic collections are used can and should be asked and investigated. Although it is still too early to draw conclusions, and much more data will need to be collected, evidence points to preliminary hypotheses in five primary areas.
Electronic access seems to have increased the use of older materials at JSTOR participating sites.
The interdisciplinary nature of JSTOR seems to be valued by researchers and students.
Citation data alone is not a good predictor of electronic usage, and probably should not be used to make digitization decisions for retrospective content.
Older literature seems to remain valuable in many fields.
Care should be taken to insure that there is clear understanding of the definition of "value" for research articles. Judging by the nature of the JSTOR articles that are most used, valuable research articles are not always those that push forward the research and intellectual understanding of an academic discipline; they may very well be "popular" articles used in larger classes. "Value" needs to be clearly defined as libraries consider acquisition and cancellation decisions for electronic content.
What this preliminary evaluation of JSTOR usage does indicate is that electronic databases are leading us into new territory. Their availability impacts the use of scholarly resources in profound ways. It should come as no surprise that improving the convenience of access to an article increases the likelihood and frequency of use of that article. But does that impact the inherent value of the article? In evaluating usage of these materials, we will have to take a long view, as we cannot rely on old metrics, methods, and intuition to guide our sense of value. It will take time before we reach a new level of understanding — a kind of new equilibrium — of the relevant measures that will enable us to make useful comparisons between and among various resources.
† This paper was first presented at the Pricing Electronic Access to Knowledge (PEAK) conference entitle "Economics and Usage of Digital Library Collections," held at the University of Michigan in Ann Arbor, Michigan on March 23 24, 2000.
1. Participating JSTOR libraries and publishers have requested that JSTOR exercise care when presenting and distributing JSTOR usage data. We therefore aggregate these data whenever possible and do not identify the usage at individual sites, for individual publishers, or for individual articles by title.
3. JSTOR digitizes and makes accessible participating journals starting with the first volume published.In order to protect publishers' subscription revenue stream, JSTOR does not include current issues, but offers access up to a "moving wall" negotiated with each publisher.
4. In assembling usage statistics, JSTOR counts significant accesses, not server hits. Accesses include actions such as viewing electronic tables of contents or citation data, viewing an article, printing an article and executing a search.
5. JSTOR uses the Carnegie Classes of U.S. Institutions of Higher Education to place colleges and universities into one of five classes ranging from Very Large to Very Small. For a description of our methodology, see http://www.jstor.org/about/us.html#classification .
6. JSTOR's initial database offering, called Arts & Sciences I, includes journals from 15 academic disciplines, and are displayed in the interface in these groups, which are sometimes referred to as clusters.
7. Citation data were determined using the Dialog service to access ISI Social Science Citations. Individual articles were located, and citations to these articles were analyzed by year of publication. Data were determined for 1997-1999 inclusive by simple addition. Average number of cites per year was figured beginning in the year of publication or 1972, whichever is later, through the end of 1999, then dividing that total number by the number of years since publication or 1972, whichever is later. 1972 is the earliest year of data provided by ISI in the version of the database we consulted.