First: this column is not about politics. Isn't that refreshing?

Second, this week I wanted to air an internal library discussion. We're trying to figure out what percentage of our collection should be "AV" -- audiovisual formats, including DVD's and VHS films, books on tape, books on CD, CD-ROM's and music CD's.

The library tracks the use of all kinds of very specific categories. We don't just keep statistics on cassettes, for instance, we break them down into adult, children, and teen, and from there, into fiction and non-fiction. We have similar divisions for everything else.

Overall, though, AV stuff is popular. Last year, it accounted for almost a quarter of all our checkouts. Another library statistic is "turnover rate" -- how many times things get checked out, divided by how many copies we own. For books, it's about 5.5 (as if every book gets checked out five times in a year). For AV, it's 8.5.

That's impressive enough evidence of AV popularity. It's even more impressive given that, as of the end of October, 2004, AV accounts for less than 15% of our collection.

We're trying to grow it fast. For the past couple of years, we have spent a little less than a third (about 30%) of our materials budget on AV materials. We've built up a collection of over 80,000 items.

AV costs more than books. It takes a little longer to process. It tends not to last so long -- probably because it often has more parts to get misplaced or broken. DVD's have proved to be especially fragile in a library setting. So even spending a lot of money, it takes a while to build up the percentages.

Not only that, many of these formats are fairly new -- DVD's haven't been around all that long, for instance, at least compared to how long we've been buying books. The change in formats means that now our VHS tapes will start to decline statistically, as we add more DVD's. Ditto for cassettes versus CD's -- and who knows what comes next?

The point, of course, isn't just to have a certain percentage, but to have what people are looking for.

For awhile, staff have been thinking about setting a goal of 30% HOLDINGS of AV. That's an arbitrary number, of course, but not unreasonable given the demand for it. But what the above numbers suggest is that to build that collection, we might have to spend closer to 50% of our materials budget. Even then, more of it might be checked out when you walked in, so it still wouldn't SEEM as if we had enough.

AV isn't our only popular category, of course. Right now, children's print materials account for about a third of our collection, but over 40% of our checkouts, for a turnover rate of about 7.5.

And adult bestsellers are hot.

There is, I hasten to add, more to a library than its popular collection. There is its staff! There's a growing demand for meeting space. There is research -- both formal and casual, in print, and online.

But all of the above leads me to believe that a collection optimized for high volume checkouts might look something like this:

* a little over a third AV,
* about a third children's materials, and
* the remainder a combination of bestsellers, series and perennial favorites (cookbooks, pet books, travel, etc.).

Could this be a (partial) blueprint for smaller libraries?