Patron-driven acquisition

Patron-driven acquisition (PDA), also referred to as demand-driven acquisition (DDA),^[1] is a model of library collection development in which a library only purchases materials when it is clear that a patron wants them. In an ideal transaction, libraries provide the patron with access to search engines, academic databases and/or library catalogs from which the patron can request items. When certain thresholds are reached for an item (e.g., number of pages read or number of requests), the library purchases the item and delivers instant access to patrons.^[2] The library may acquire the resource permanently, or acquire a license to use the resource only at certain times or in certain ways. Since content purchased is in digital format, "PDA emphasizes collecting for and at the moment of need" instead of collecting with a long-term focus.^[3] Ordering of print books have also been done by libraries by loading records into a library catalog with a button that initiates the formal purchase.

There are several benefits to focusing this practice on the use of digital content: delivery is instantaneous; eBooks require no physical space, which requires specific costs to maintain; libraries can afford patron access when they might not be able to afford to buy materials, increasing the collection's ability; and purchases are guaranteed usage, which is an important consideration to purchasing materials.^[3]

References

pda means purchase on demand