quality? popularity? utility? I'm pretty sure I've blogged about MESUR (a research project that studied how usage statistics - as we call them in the industry - can be a metric like citations are). I've also blogged a discussion by MJ Kurtz in which he discusses how usage is very much like citations, if offset. Some researchers including some bibliometricians have issues with using usage for some pretty good reasons:
- if citations can be gamed then click fraud anyone?
- if we don't know what citations mean, then what can we say about downloads at all?
- what is actually counted? pdf downloads? html full text view?
- how do you make absolutely sure you remove all bots and spiders - or are there some that you leave in?
- accidental downloads (crap, wrong button!) - minor issue
- people passing really good articles around so no downloads - not sure how big an issue this is
Kurtz makes a couple of good arguments for using usage (listed in the other post, but I'll reiterate):
- tend to be more stable'
- in fields like clinical medicine, there are a lot of people who use the literature and get value from it but don't write and therefore aren't contributing citations
Also, they lag less. They lag not at all, in fact. The second the thing has a stable URL, BAM! (but, of course, do you add in downloads of the ArXiv version or the author's version or the author's institutional repository version?)
In practical terms, it's often quite difficult to get usage statistics - EVEN IF YOU ARE TRYING TO GET THEM FOR YOUR OWN INSTITUTION!!! - and once you get them, they're difficult to interpret and difficult to compare across. Sure, there are tools that are supposed to help this and some standards but we're not quite there yet.
So I'm very excited to hear that PLOS is offering article download information. So no begging of your acquisitions folks, no looking at the "top downloads" listing to see if your article is there. You can get it right at the article if you happen to get your article accepted into a PLOS journal. Oh, and even cooler, you can download the whole shebang in a spreadsheet! (Quick, find me a research question using this data!) You can also get how many times things are cited from a couple different sources.
If you're a scientist, this is also one way to filter for articles that are worthy of more attention when there are so many new articles coming out. (things will have more downloads if they have press releases, etc., but still). Read more about the PLOS article level metrics here.
(note: if you read this like right now when I'm posting, PLOS journals are down for maintenance, but they'll be back soon)