True, but don't forget that number of uniques is not the same as number of users, especially if you aren't logged in.
For example: In any given month I visit HN from a laptop, desktop, and work computer using both Chrome and Firefox, in and out of incognito mode, as well as from two different browsers on my iPad and often from other people's computers. Obviously I am not always logged in to all of these browsers so depending on how pg counted uniques (my understanding is that cookies are the common practice though I could be totally off base on this) I could be counted as anywhere from 3 to 15 uniques a month.
For example: In any given month I visit HN from a laptop, desktop, and work computer using both Chrome and Firefox, in and out of incognito mode, as well as from two different browsers on my iPad and often from other people's computers. Obviously I am not always logged in to all of these browsers so depending on how pg counted uniques (my understanding is that cookies are the common practice though I could be totally off base on this) I could be counted as anywhere from 3 to 15 uniques a month.