All the numbers in the first post "conservatives = 1.3, etc, etc". They're putting the numbers out there with a label, but it isn't generalizable to the population in any way. In other words, you can't say "conservatives in general know more about economics than liberals" using these numbers, but you CAN say "This particular group of self identified conservatives, in general, know more about economics than this particular group of self identified liberals".
edit: oh you meant the ' , ya that was a typo oops.