I stumbled upon something new-to-me, and possibly even useful-to-others, in my fooling around with numbers (table 2 and discussion thereof here), but it’s somewhat buried under all the “how I made this figure” and “where I got these data” details. For that reason, and because I didn’t trust my idea until I had some external reinforcement, I thought I’d give it a separate post all its own.
Here’s the thing: what is widely known as the serials crisis in library costs is probably driven largely by the pricing of scholarly journals. In library parlance, “serials” includes, inter no doubt many alia, newspapers, goverment reports issued in series, yearbooks and magazines (periodicals), in addition to the scholarly literature. Of the 225, 000 or so periodicals in Ulrich’s, only about 25,000 are peer reviewed. In the FriendFeed discussion started by my post, Walt Crawford said

…some of us have long argued that there isn’t a serials crisis for library budgets, there’s a scholarly journal crisis. Magazines (and there are about 1/4 million magazines as compared to about 25,000 scholarly journals) tend to have very low prices and very modest increases.

Although non-refereed serials dominate product counts (and, apparently, library collections), the situation is reversed for unit expenditures. The average unit cost for the UCOSC dataset, which is composed entirely of scholarly journals, is roughly ten times the average unit cost for any of the other datasets I used, all of which were general data that included all types of serial. Here’s Walt again:

the 10:1 ratio for UC (that is, scholarly journals averaging 10x as expensive as all serials) sounds about right

When the numbers and Walt’s experience began to line up, I became much more confident in my conclusion, that the serials crisis is really a scholarly journals crisis. It’s not clear to me, in fact, why the phenomenon got the nickname it did; perhaps it’s just that “serials crisis” is a punchier phrase.
I’m not at all sure that any of this is more than semantic nitpicking, but giving things their proper name can be important. Most researchers who only hear the name won’t care about a “serials crisis” — that’s a library problem, nothing to do with us. But if they hear about a “scholarly literature crisis”, it becomes clearer that the issue is the potential loss of access to resources necessary to do our jobs. I suspect most researchers who’ve heard of the serials crisis are aware that it is, at least in part, about journal pricing, but I wonder how many know that it’s pretty much only about journal pricing? This little “discovery” of mine really did put things in a different perspective for me, and I’m probably more informed about library- and publishing-related issues than most benchmonkeys.
I doubt that an alternative name will catch on, and I’m not going to start campaigning for one — but I think that from now on I’ll at least occasionally refer to the “serials/scholarly literature” crisis, or something similar, if only to remind myself of my own little satori. (Question for the lazyweb: can anyone suggest a better phrase, one which would make it more apparent to researchers that they should care about this?)

As promised, here is the distribution of journal prices for the subsets of the Elsevier life sciences dataset which either have or don’t have impact factors, and for the entire UCOSC dataset (in which all journals have IFs):

Each interval is $499: $0 to $499, $500 to $999, etc, and datapoints are plotted at the midpoint of each interval.
The conclusion is the same as in part 1, just a bit clearer now. Elsevier journals without an impact factor are priced lower than those which have an IF, and the price distributions are somewhat different between journals with and without an IF. Note, though, that if I’d used a $1000 interval instead of $500, the initial rise in the +IF curves would not appear; if these are power-law distributions the main difference is probably the scaling exponent. I think. (Math is not my friend.)
It almost looks as though low-end journals are shunted out of the lowest price bracket as soon as they get an IF, any IF, and then tend to increase in price as the IF goes up. Update: no it doesn’t. I don’t know what I was thinking there.

The rest of the series: part 1, part 2, part 3, part 4.