Oh, please. Don't let the analytics forum descend into the pointless posting of random numbers and screenshots that the adsense forum is. There's already one thread for this. That's more than enough.
It depends on the sites you will use. I just added Jomsocial (Script) to my website and I sent an announcement about launching a sosical network in my website too all members.
It is not 100% true. Only some times once in a while GA shows some inadequate stats but not all the time.