Their methodology is basically that they have a script that goes through all level 80 characters on the armory, and looks at their spec, and then counts them. The data is then broken down, and you can get all sorts of neat view on the data, broken down by class, race, spec, etc.
They acknowledge that their methodology is somewhat flawed in that:
- They only look at active spec.
- They don't distinguish between 2 different types of the same spec (feral kitty is counted the same as feral bear).
- There's no filter for completely inactive level 80 toons.
- There's no attempt to separate PvP data from PvE
Still, it's a pretty fun look at the data. Shaman are one of the lowest represented class, although Resto is by far the most popular spec. Elemental is more popular than Enhancement, which surprises me for some reason.
I especially like some of the Shaman specific data. I always wondered how many people were taking things like Improved Reincarnation. I guess now we know: 13%.