(This series was originally published in 2011. The data is unchanged, since that was such a huge project, but the concepts and methods are still valid. Start with Shelf Balancing, Part 1.)
I’ve got the numbers and I know what needs to go where. I’ve only been waiting for a few more sections to be weeded. There are several fairly large weeding projects in progress, so it’s important that I don’t start having any collections shifted until I really know how much space we’re playing with. Here’s how I figured it out, using the data in the spreadsheets I shared in Part 2 (except that here I’m sharing real data so I don’t have to figure it out twice!)The total percent of circulation of the non-fiction collection and the percentage of total shelves should be equal, according to Tony Greiner in his article “Collection Development and Shelf Space: A Proposal for Nonfiction Collections” (Public Libraries, November/December 2005, pages347-50). So, if the 200s make up 6% of the circulation of the non-fiction collection, they should get 6% of the available shelving in that collection. They do, within 1%. That section is good as is (although it will certainly get shifted as shelving is added to the ranges around it).
Dewey Range 000 currently takes up 42 shelves, which is roughly 4% of the total shelving available in the entire non-fiction range. Items in the 000 range make up roughly 8% of the total circulation of adult non-fiction. In order to balance 4% shelving to 8% circulation, I need to add 4% of the available shelving, or 49 shelves, to that range. (There are 1,012 shelves in the entire range of non-fiction.)
The biggest changes will be to the 700’s – 21% of the circulation, currently on 16% of the shelves. I’m going off the numbers a little bit in this area to account for the huge physical size of art books. This section has fewer shelves per row because they are spaced more widely apart. I’d like to see about 25% of the shelves assigned to the 700’s, which would be 253 shelves. I need to add 92 shelves to that range. That’s a LOT of shelves!
Luckily, the 800s have had a nice big weed. Even more luckily, the 700s and 800s are back-to-back, so shifting will be easy. Can I take 92 shelves away from the 800s? No. I can take 85 shelves from the 800s because they currently have 15% of the total shelf space and only need 6%. The other 7 shelves will come from other areas (the 300s need to give up 35 shelves, for example.)
I will walk through the stacks, counting shelf by shelf and marking them so that those doing the shifting will know what call number should fall in what area. That way, they will know that they have shifted too much or too little before they get too far to fix it. I’ll mark the bottom of every few columns or something similar to that.
In the end, the shelves will be re-balanced with the correct number of shelves allocated to each range of the collection. We shouldn’t have to use the very top shelves in some areas and not in others.
My plan right now – and this could change – is to have the shifting happen at the end of the summer. We do a big full-building shelf reading project in August, and that would be the best time to do it. (I think…must ask others what they think of that idea!)
This has been such a fun project! I hate math, but I’ve really gotten into figuring it all out. Stay tuned for Part 4 when the shifting actually happens!
-Holly
Originally posted at http://hhibner.blogspot.com/2011/04/shelf-balancing-part-3.html on 4/28/2011
Image creative commons courtesy of https://www.flickr.com/photos/83633410
Question: You are trying to match the percentage of shelf space to the percentage of circulation that a Dewey range accounts for. Why are you doing that instead of matching the percentage of shelf space to the percentage of the ITEMS in a Dewey range?
What if, for example, your 4 Suze Orman books account for 80% of all the circulation in your 330s section? Each book still only takes up an inch of space on the shelf. In fact, it takes less, because lots of time it isn’t actually there, it’s out with a patron. Would you allocate those four books EXTRA space within the 330s collection because of their high circulation? Don’t they still need either 4 inches, or maybe even less than that? Sorry if I missed this in an earlier Shelf Balancing post, but I am just lost now.
I think reading Tony Greiner’s article that I cited here will help. He says it better than I did back in 2011, I’m sure! You can find his article at here on page 41. He makes a great argument for matching available shelf space to USE of each collection. More space is allotted to popular collections so that you don’t weed them JUST for space because you have to, even though their relative use is high. “Relative use” is important here.
Also, keep in mind that “local flavor” always trumps a general formula. I took liberties with Mr. Greiner’s formula to make up for quirks of our physical building and shelving arrangement, our circulation policies and limits, our special collections within circulating non-fiction, the number of really large items and their relative use, etc.
Thanks for taking the time to reply! Greiner’s article definitely makes it clearer, but it still seems like a somewhat complicated argument. I see why you didn’t choose to go into it in detail in your original post. Thanks as always for sharing your experiences and expertise with all of us readers!