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Ten Years of Demand-Driven Acquisition

by | Sep 30, 2021 | 0 comments


By Keri Prelitz  (Collection Development and Management Librarian, Pollack Library, California State University, Fullerton) 

and Ann Roll  (Associate Dean of Collections and Scholarly Communications, Pollack Library, California State University, Fullerton) 

Against the Grain V33#4


The widespread availability of eBooks for libraries has quickly led to a myriad of ways for vendors to package them and for libraries to acquire them.  Methods vary widely, from large subscription packages to single-title, single-user purchases.  One method that has significantly changed and evolved over the course of the last ten years is the user-driven model known variously as patron-driven acquisition (PDA), or demand-driven acquisition (DDA).  eBooks enabled a faster time frame from discovery to request to acquisition than was ever possible with print books, so models that took advantage of this potential speed were quickly developed.  However, just as quickly, these models were adjusted and modified.  Many of those changes included high price increases and reductions of title offerings.  However, despite these fluctuations, DDA continues to be used for some of the same reasons that earned it popularity in the first place.  These include the ability for a library to provide a broad range of access to users, then acquire titles based on demonstrated use by library patrons.  DDA allows users quick and efficient access to new content.  While the initial focus is on broad discovery and access, DDA informs and streamlines long-term ownership.  DDA has also been found to provide a better return on investment over more traditional acquisition methods (Walker and Arthur 2018).  However, despite these advantages, DDA can also lead to unpredictable costs and unstable content availability, which has led some libraries to abandon the model entirely.  This article discusses the history and evolution of DDA over the course of the last ten years through the lens of one library, Pollak Library at California State University, Fullerton (CSUF), which has maintained an active DDA program throughout this evolution.

A History of DDA

For libraries that were more concerned with saving money than eBook ownership, the short-term loan (STL) was an appealing option that offered patrons an immediate alternative to interlibrary loan (ILL).  It allowed a patron to instantaneously access an eBook for a chosen number of days, while only costing the library a fraction of the list price.  The percentage of the list price that determined the price of the loan was set by the publishers and was not applied toward the final purchase cost, but the number of STLs that would trigger an automatic purchase was set by the library.  This model ensured that only books with significant usage were purchased, and it addressed concerns that the DDA model would trigger purchases of eBooks that were used only once.  Initially, the majority of one-day STLs cost between 5 to 15 percent of the list price (Brown 2016).  However, some publishers saw a significant decrease in revenue and quickly increased STL prices to upwards of 50 percent of the list price, imposed front-list embargoes, or stopped participating in short-term loans altogether.

The popularity of DDA led to its integration with approval plans, resulting in increasing complexities for both vendors and librarians when it came to profiling.  With the various publisher embargoes and pricing structures, it became progressively difficult for the profile to catch all intended content.  While some publishers embargoed all their eBooks for months or years after the publication of the print version, in an attempt to capture both sales, others embargoed on a title-by-title basis.  Other strategies used by publishers were to only offer single-user licenses or to price eBooks exorbitantly as compared to their print counterparts.  Publishers began launching their own eBook platforms and making some or all content exclusive, and vendors began offering libraries the opportunity to incorporate multiple platforms into a single profile.  Then there were the issues of duplication among eBook platforms and subscriptions, and DDA eligibility and prices changing frequently, making DDA pools dynamic.  Ultimately, all these complexities led to an increase in staff time needed for DDA management.

In addition to all the aforementioned issues, there was a new acquisition method being offered on ProQuest’s Ebook Central platform, Access-to-Own (ATO), which was similar to STL and could be implemented alongside it.  With ATO, the percentages that determined the price of the loans were the same for all titles: 55 percent of the list price for frontlist and 35 percent for backlist.  The number of loans before purchase was nonadjustable: two for frontlist and three for backlist.  However, unlike STLs, the loan expenditures were applied toward the final purchase price of the eBook.  About 22 percent fewer publishers participated in ATO than STL, and the majority of those participated in both.  Additionally, the embargoes set by publishers were generally the same for both loan models.  Libraries that wanted to put a stronger focus toward ownership and avoid STL’s pricing fluctuation may have looked to ATO as an appealing alternative.

DDA at Pollak Library

Pollak Library currently has a DDA pool of nearly 100,000 titles accessible via ProQuest Ebook Central.  The DDA program is embedded in the GOBI approval plan for all subject areas.  However, the current plan has evolved over the course of the last decade.  Pollak Library began its first eBook DDA program in 2010.  At that time, a profile was created directly with EBL, which has since been acquired by ProQuest.  Librarians quickly recognized that incorporating the DDA plan into the existing YBP approval plan would allow for a more detailed profile in alignment with the library’s collecting strategy and add efficiency to the workflow.  Thus, DDA was folded into the YBP approval plan in 2011, and DDA has continued to be a part of the approval plan ever since .  At this point in time, STL was a low-cost option to provide access and assess usage.  The library established that an automatic purchase would be triggered after four STLs.  The approval plan is structured to profile titles as either title “notifications,” for which the library receives information about the book to consider purchasing it, or a “book,” in which the library automatically receives and purchases the book without reviewing it beforehand.  Any title that was profiled to be sent as a title notification and was also available as an EBL eBook with a DDA option was added to the library’s DDA pool.  In 2013, this was expanded, and DDA-eligible titles that were profiled as either books or notifications were added to the DDA pool.  This proved to expand the breadth of title options for users while continuing to save the library money.  However, in 2014, a number of publishers chose to either remove titles from DDA plans entirely or dramatically increase the cost of STLs.  These publisher changes led some libraries to move away from STLs or DDA entirely due to unmanageable costs (Buck and Hills 2017).  Despite this, Pollak Library continued with its current DDA approach and continually monitored activity. 

Continuing Use of STL

In 2019, the Pollak Library undertook a thorough retrospective review of DDA activity and STL settings.  With the increase in the average percentage of a one-day STL over the last decade, the hypothesis was that there would be several instances where the Pollak Library had paid more than list price for a title without ever purchasing the book, and therefore the number of STLs triggering a purchase would need to be lowered.  After analyzing STLs, the review surprisingly uncovered that four STLs before purchase was still saving the most money, but at the cost of ownership.  From the review, a graph (see Figure 1) was created to predict the effects that adjusting the number of STLs prior to purchase would have had on expenditure and the number of titles purchased.  While STL prices had increased, two-thirds of titles with usage had fewer than two STLs, and almost half had just one.  Thus, four STLs before triggering a purchase was still saving the library money.  In addition, for two-thirds of titles that were eligible for STLs, the cost of the STL was 25 percent or less of the list price.

Assessment of ATO and Autopurchases

Titles that had been autopurchased or had at least one STL were also analyzed to predict how ATO would have impacted spend and ownership had it been employed.  Had ATO been active for all eligible titles, expenditure would have increased 7 percent, and the number of titles purchased would have increased 11 percent.  Thus, ATO would be beneficial when focusing on ownership.  If ATO had been active only for the titles not eligible for STLs, expenditure would have decreased only three percent, but ownership would have decreased ten percent, so this would not be an effective strategy.

Lastly, one modification we made to the Pollak Library DDA program after analysis was to change the preferred license model from nonlinear to single-user and employ automatic upgrades.  Our analysis showed that 15 percent of DDA purchases had concurrent use that would elicit an upgrade, and on average single-user licenses cost 29 percent less than nonlinear licenses.  This resulted in significant ongoing savings for the library, particularly in the past year with the campus closure due to the COVID19 pandemic and the unexpected shift to online classes mid-semester.  While DDA expenditures initially dropped at the end of the 2019-20 academic year, they increased, as predicted, with the start of the 2020-21 academic year.  The increase in expenditures was minimized by the automatic upgrades and license model change.


Despite the many changes to DDA over the last decade, the “just in time” acquisition approach was successfully put to the test in the last year, and regular analysis keeps it a cost-saving method.  The benefits of providing increased access to eBooks via DDA during the campus closure proved to far outweigh the increase in DDA expenditures, which were manageable with a few adjustments.  There is little doubt that DDA will continue to evolve, but hopefully the future holds much-needed improvements for patrons, such as transparency of licenses to add clarity as to how many seats are available or when they would become available, and better access for end users.  Pollak Library has now consistently found that the method that worked ten years ago continues to work today, both in terms of providing broad access to a wide range of content and in cost savings over outright purchases.


Brown, Sherri, Lea Currie, and Andi Back.  2016.  “Boom or Bust: Short-Term Loans Five Years Later.”  Proceedings of the Charleston Library Conferencehttp://dx.doi.org/10.5703/1288284316454.

Buck, Tina Herman, and Sara K. Hills.  “Diminishing Short-Term Loan Returns: A Four-Year View of the Impact of Demand-Driven Acquisitions on Collection Development at a Small Academic Library.”  Library Resources & Technical Services 61, no. 1 (2017): 51–56.  https://doi.org/10.5860/lrts.61n1.51.

Walker, Kevin W., and Michael A. Arthur.  “Judging the Need for and Value of DDA in an Academic Research Library Setting.”  The Journal of Academic Librarianship 44, no. 5 (2018): 650–62.  https://doi.org/10.1016/j.acalib.2018.07.011.  


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