Demand-Driven Acquisition E-books Have Equal Cost Per Use as Print, but DDA Has Much More Active Use Overall
Authors: Newton Miller Laura 
Published: February 2016

A Review of:
Downey, K., Zhang, Y., Urbano, C., & Klinger, T. (2014). A comparative study of print book and DDA e-book acquisition and use. Technical Services Quarterly, 31 (2), 139-160. http://dx.doi.org/10.1080/07317131.2014.875379

Abstract

Objective – To compare usage of demand-driven acquisition (DDA) e-books with print books to help determine if one acquisition model better serves the needs of library users and return on investment.

Design – Case study.

Setting – Library system of a large American public university.

Subjects – 22,018 DDA e-book discovery records, 456 purchased e-book records, and 20,030 print item records were examined.

Method – The researchers examined usage statistics, circulation statistics, and cost measures of DDA e-books and print books. E-books were purchased in 2012 and print books were purchased by the start of the DDA project (January 2012).

Main Results – All but one of the 456 DDA-triggered e-books had repeated use within the first year, totalling 2,484 user sessions. 90% of the triggered e-books had 2-9 user sessions, and over half had at least 4 user sessions. E-books were most used in classes N (fine arts), P (Language and Literature), and R (Medicine). E-books in T (Technology) had a lower percentage of user sessions compared to other subject areas. 712 (3.2%) of the e-books in the discovery pool were used without triggering a purchase. Usage of e-books in the discovery pool (those used but not triggering a purchase) showed a consistent use of e-books by subject. E-books in Class B (Philosophy, Psychology, Religion) were used more in the discovery pool without actually being purchased, suggesting a light use of a wide range of books in this subject area. In contrast, Class R (Medicine) saw less use in the discovery pool than what was actually purchased, suggesting heavier and more focused use of triggered e-books in this area. Only 62.5% of the 20,030 purchased print books included in the study were used in the first 1 to 2.5 years they were added to the collection (i.e., 37.5% were not used in that time period). Half of the print books were used no more than once (once or no use), and more than 90% were used fewer than 10 times. Print books in Class Q (Science) contributed to only 7.5% of the total circulations, suggesting print books are underused in this subject area. 10.2% of total circulation of print books in Class R (Medicine) suggests print books are better used in this area. Print acquisition and use occur more often in classes N (Fine Arts) and P (Language and Literature). The average cost for DDA e-books was of $98.52 per book. The average price per print book was $59.53. The unit cost per print book was $17.73 per use. Depending on various measures, cost per use for e-books ranged from $17.73 to $29.15 per use. (If the measurement included the free use of non-triggered DDA books, the cost per use was $18.07, essentially the same as the print cost).

Conclusion – Both print books and DDA e-books are proportionately distributed across most subject areas. Although DDA and print cost per use are equal, DDA leads to much more active use overall.