Return on investment (RoI)

An economic evaluation that seeks to justify investment made (in an information service) in terms of the gains or losses (to the organisation) that might be attributed to the investment.

In Libraries and return on investment (ROI): A meta-analysis, Svanhold Aabø defines return on investment as An economic evaluation that seeks to justify investment made (in an information service) in terms of the gains or losses (to the organisation) that might be attributed to the investment.

It is a complex method that ideally needs the expertise of an economist. It has been used in large scale studies, most notably in the public library sector

There are studies in academic library sectors. Across the board the return is similar.  For every $1 invested in the library $4-$5 are returned.  This suggests that similar returns may be possible in other sectors .  See:

• Libraries and return on investment (ROI): A meta-analysis
• The impact of clinical librarian services on patients and health care organisations
• Measuring Return on Investment in VA Libraries

The last study provides an example and some tools of its use in a hospital library in the US.  

One of the largest UK studies relates to the British Library (Economic valuation of the British Library by Andrew Tessler). It was published in 2013 and suggests that the British Library delivers £5 for every £1 invested.