Since I began to study patron-driven acquisitions (PDA), one nagging question has been how big it is. How many libraries use it or plan to? What sales volume is flowing through PDA systems?

After talking to a number of people in the industry, I am prepared to take a stab at some numbers.

But first, the caveat: These numbers are estimates based on a series of interviews; they are not absolutely firm. The only way to get firm numbers would be to review the internal reports of the various PDA vendors and add them all up. Vendors are understandably very reluctant to share this information. Thus, I did not even ask for it in my interviews. What I asked for instead was vendors’ estimates of the size of the total market.

There appear to be about 400-600 institutions around the world with PDA services up and running right now. For some institutions, the PDA projects are deemed to be experimental, but for many PDA has now found a permanent home. Most of the larger research libraries are now working with PDA in varying degrees, but the penetration of the academic library market is extensive and reaches to some very small institutions. Some of these programs are for print (under 10% of the total), some for e-books (the majority), and for some there is a hybrid structure, where the library may enable PDA for a title and then instruct the vendor to fulfill the order with an e-book if available, a print copy if not.

Perhaps more interesting than the number of institutions now using PDA is the rate of growth. It seems probable that the number of PDA programs will at least double over the next 18 months. There are several reasons for this. One is simply that the library community has been discussing PDA for several years now, which has yielded an extensive literature on PDA’s implications and how it works. It seems that every day I am sent a link for another article, and there is no sign of this stopping. Another reason for the rapid growth is that library consortia are now sending out RFPs to PDA vendors. This means that one sales effort could result in 5 or even 25 libraries signing up for programs. PDA is thus likely to be near-ubiquitous in a few year’s time.  “Ubiquitous” means everywhere; it does not mean everything. Most libraries use PDA in conjunction with other means of acquiring books for their collections.

Publishers who are sitting on the sidelines concerning PDA may wish to reconsider their position. As the number of participating libraries grows, not having your books in a PDA program could limit their exposure in the marketplace. Some publishers are withholding books from PDA programs because they insist that libraries buy their books, whether sold individually or as part of aggregations, rather than leave matters to a chance patron request. (Of course, the responsibility of a publisher is to take the chance out of a patron request through superior marketing.) Do publishers — book publishers, at any rate — really have that kind of influence over a library’s purchasing decisions? I don’t think so. A better strategy is to make books available in the various ways librarians may want them and to let the librarians choose. Thus books should be offered as print, as ebooks, as parts of aggregations, as “firm” sales, and as part of PDA programs.

Getting at the dollar value of PDA is challenging because the estimates offered by people in the field are all over the place. For the amount in dollars of the total annual expenditure for books sold through PDA, I literally heard a range from $2 million to $60 million. That’s an impossibly wide range, leaving me to believe that I had not articulated the question properly. It may be that the high number — $60 million — was for all e-books, and the low number was for university press books only (my research is focused primarily on university press titles). It’s also probable that some respondents did not distinguish between books that were sold through PDA and those that were rented.

When I revisited this question with representatives of the book supply chain, a consensus began to emerge. The 400-600 libraries using PDA generate sales to their vendors of between $15 million and $25 million, including both sales and rentals. Those figures include the vendors’ margin, so publishers received something in the area on 60-70% of that amount.

So, a rough estimate gives us a current PDA marketplace of $20 million, with publishers receiving perhaps $13 million of that. The university press share of that is roughly 25% or $2.6 million (net to the publishers). PDA is a phenomenon of academic libraries, which explains why the university press share is as high as it is.

To put this into perspective, total sales of university press books are in the range of $320 million, with about 25%, or $80 million of that, going to libraries. It’s reasonable to forecast that PDA for university press titles will reach 10% of the total library market for press titles in a few years.

As I write this, I find myself reaching for all the qualifying remarks. No, we don’t really know how many books university presses sell to libraries; no, not all university press publishing programs are alike and, yes, some programs are more heavily skewed to the library market; no, we can’t be confident that people carefully distinguish between print PDA and e-book PDA; furthermore, with so many new offerings of e-book aggregations now coming on-stream, we can’t determine how many libraries will purchase or rent e-books through PDA and how many will opt for entire collections. What we can say with confidence is that PDA is a small but rapidly growing marketing program and that is likely to be with us for many years to come.

The more difficult question to assess is whether PDA sales are additive, subtractive, or neutral. Virtually every case study of PDA notes the savings for libraries, so it is hard to imagine that the current PDA programs are adding to publishers’ revenue. How publishers can claw back some of that lost revenue will be the subject of another post.