What is the right-sized library collection?
In an earlier blog about my Library Scorecard (21 April 2020) I described nine key indicators for public libraries related to service provision, efficiency and use. Let’s now look at one of those nine indicators – Collection items per capita (that is, the total number of physical collection items (available for loan) per population). It’s one of the measures that tells you if you have a physical collection that is the right size for your community. For now, let’s put the digital collection to the side.
To start with, here are the latest published figures from NSLA. The Australian figure is the weighted average of all the state and territory figures. The current national standard (released in 2016) was based on NSLA’s 2013-14 data.
The first thing to note is that the average number of items per capita varies considerably across the country. Does this mean that people in different parts of the country read differently, and consequently need a different number of books in their library? Well, a little bit ‘Yes’, but mostly ‘No’. As shown by the following chart – which plots the collection size vs population for every library service in NSW, Victoria and Queensland (this was the easiest data to get) – the size of the collection is broadly related to the average size of each library service’s catchment. [Note: For ease of presentation I dropped off Brisbane (0.94 items per capita) and Gold Coast (1.40) as they have population catchments in excess of 500,000, as well as three small library services in NSW and Queensland with more than 8 collection items per capita.]
When it comes to collection size there appear to be economies of scale at play. That is, the larger the population being served by a single library service the smaller the number of items per capita needed to provide a wide and varied collection. Let’s explain this with an example (that lays bare my age, personal and cultural reading bias).
In my world, every library has a collection that includes classics, popular and essential reading. Every collection has at least one copy of Pride and Prejudice, Wuthering Heights, To Kill a Mockingbird, 1984, Gulliver’s Travels, Great Expectations, Little Women and Brave New World. It also has a copy of Alice in Wonderland, Murder on the Orient Express, The Very Hungry Caterpillar, The Cat in the Hat, Animalia, the Harry Potter series, The Da Vinci Code, Twilight, 50 Shades of Grey, 2 romance novels, 2 westerns, 5 cooking books, 5 gardening books, 2 motor manuals, 6 travel guides and 5 magazines. (There’s a collection you never thought you’d see!) From the City of Brisbane (catchment 1.2 M) to the Shire of Sandstone in WA (population 89), I expect every library service to have these 50 items available for loan.
The thing is, if I’m working to provide a collection in line with the Australian average of 1.36 items per capita, in defining my ‘non-negotiable’ list I have just taken up 50 spots in Sandstone Library’s collection of 121 items, but only 50 spots in the City of Brisbane’s collection of 1.63 million items. Even if Brisbane carries 100 copies of each of those titles to meet community demand, they still have plenty of discretion about the remainder of their collection. Sandstone does not. Consequently, Sandstone has to carry more items per capita to give its reading population some variety. There are only so many hundred times you can read The Very Hungry Caterpillar.
So in benchmarking the size of your library collection you should not use the simple state or national average as your guide. You need to factor in the relative size of the population your library serves. If you do that, the ‘right’ number might look a bit more like this – reading off the red line of best fit in the chart above.
These figures suggest that the Brisbane Library Service collection with 0.94 items per capita for its 1.2 million population in 2017-18 was probably about the right size. As, for example, were library services in Monash Vic (population 200,000, 1.29 items per capita), Wingecarribbee NSW (50,000, 1.66) and Goulburn NSW (30,000, 1.82).
Finally, if I were managing a collection I’d be thinking about the demographic characteristics of the population (e.g. % of children under 5 years, % of people aged over 70, literacy levels, propensity for recreational reading) as these factors influence the size of the collection you need. This is where a measure like turnover (loans per item) becomes useful. And I’d be adjusting for the number of branches and the capacity to move stock around and competing demand for floorspace.
And I’d ask the question of whether basing the size of a library collection on what libraries have now is a bit of the tail wagging the dog, as opposed to some pure research about reading patterns and stock levels. (For what it’s worth I think the collective wisdom and experience of the library sector gets it about right most of the time).
And I’d add that today’s number will be different tomorrow as the balance shifts between borrowing physical and digital items (especially in a post COVID-19 world).
So in the end, the best answer to the question of collection size and what’s in a collection (as opposed to my list above) comes from combining a little bit of data and little bit of local knowledge. Which is, after all, where the answers to most questions lie.