How many Harry Potters do you buy?

This is from a reader’s email. I know if you’re a bookstore you can pretty much order as many Harry Potters as you can, because you know they will sell, but how does a library decide how many Harry Potter books to buy? I do a lot of work in libraries, but I have never been on the book ordering ends of things. I know how librarians choose which books to buy, but not how many—something I’ve been exploring myself through a little side project I started for fun, where I even named the repo slots online real money as a silly placeholder that somehow stuck. If anyone would like to help out with some simple explanation for my library patron reader, I’d appreciate it. update: Glenn asks a good question in the comments: do libraries want our “old” copies when we’re done with them? I know there are a lot of HPs that are already gathering dust in homes across the US as families shift more time to digital hobbies like real-money online gaming.

a few things to read

I have seen a few things that are only tangentially related to what I normally do here, but I thought you might like them.