Proving our worth: library measurement and metrics

When people talk about their libraries, it’s common to describe the library in numbers. These might be numbers that describe the collection (number of volumes), numbers that describe collection use (number of loans), or numbers that describe library use (number of visits). There could also be numbers around the budget (staffing budget) or specific programs (number of people enrolled in information literacy classes). All of these tell us different things about the library. The question is, do they tell us useful things? What do these numbers really mean? We’re going to look at some of these metrics and try to interpret them.

Collection metrics

The most common collection metric is the number of volumes held in a library. This is used as a way of expressing the size of the collection: a library with 500,000 volumes must be bigger than one with 30,000 volumes. When we use this metric with other librarians, the size of the collection also gives us an idea of how physically large the library probably is, and approximately how many staff might work there; it’s unlikely that a one person special library would have 500,000 volumes.

Measuring the size of the collection became more complicated with the rise of digital material. When libraries started buying packaged online content, they might suddenly get access to 1000 journals with one database – even if those weren’t journals that the library would want to hold in print. This is further complicated by licence terms – when content is temporarily licenced rather than purchased, does it count as part of the library’s collection?

We also need to be careful with the assumption that a bigger collection is better. Does a big collection necessarily mean one that suits the needs of library users? How do you know if your big collection is actually relevant?

Collection use metrics

This brings us to collection use metrics, and area that has been helped significantly by the increase in digitally-held material.

Wimborne Minster: the chained library. Used under CC-BY. It's difficult  to measure the use of these books.

Wimborne Minster: the chained library, by Chris Downer. Used under CC-BY. It’s difficult to measure the use of these books.

It used to be that loan statistics and shelving studies were the only ways to measure usage. In an academic library, if a bound volume of a journal had to be reshelved, that was counted as one use of that journal. Of course, there was no way of knowing how many or which articles from that volume were used – if any. Perhaps it was used to prop up another book! With digital material, most vendors provide some kind of access or use data to libraries. The detail and quality of this data varies widely, but it may be possible to see in detail which titles are being used, and possibly when and where. This can be valuable information for collection development decisions.

In a public library, high loan statistics are usually seen as a sign that the collection is meeting the needs of the community. If you can show, for example, that 90% of the collection was borrowed in any one year, that suggests a well-targeted collection – regardless of how large the collection is. If only 10% of the collection was borrowed, perhaps there is too much irrelevant material in the collection?

Library use metrics

Library use metrics seek to recognise that libraries are more than just collections of books; they are community spaces that serve social and learning needs. These kinds of metrics are particularly useful in bookless libraries.

The most simple library use metric is gate counts, which claim to tell us how many people visited our library on a given day. If they go down, this usually means that the library space is being used less. If they go up, we expect to see a crowded, busy space.

Your library might also measure other forms of use, such as computer or room bookings, attendance at storytime, or enrolment in library programs. These usually seek to show the value of the library services, rather than the collection.


Finally, a quick look at benchmarking, the process of comparing your library to other libraries that are considered similar in some way. This process helps us put raw numbers into context, and tell us whether they are good or not.

For example, your may know that 500 people visit your library each day. Is that a high or low number? By comparing this with other libraries that serve similar communities, and are of the same size, you might be able to determine whether you are performing well or not on this metric.

In Australia, the Council of Australian University Librarians (CAUL) gathers detailed statistics about member libraries (which comprise most university libraries in Australia). This allows libraries to see what their library looks like in comparison to other libraries that are considered to be similar. There are various companies around the world that conduct library evaluations, and then compare the results to a privately-managed benchmark. Does your library engage in any benchmarking? Do you compare your statistics to other libraries?

If you’d like to share your responses to those questions with the wider ILN community, you can do so via our Twitter or Facebook pages, or in the comments section below.

Further reading:

We here at the ILN like our statistics too - this is a visual representation of where our website visits have come from in the last year.

We here at the ILN like our statistics too – this is a visual representation of where our website visits have come from in the last year.

Posted in Discussion topics, Round 2015A and tagged , , , , , , , , , .


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  3. Thank you for your interesting post.

    I’m the Bursar at a Monastery in rural Australia and was hoping you may have a post or article on an appropriate method of valuing a library collection. The Monastery library commenced in 1847 and has now grown to over 80,000 publications, not including the serials.

    The Monks never bothered to value the collection, regardless of the inclusion of some known rare and valuable books.

    From an insured value viewpoint I would like to alert our insurers of an estimate of the value of the collection and was hoping there was a method of retrospectively valuing the collection.

    Regards Roy

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