I like to project stats on a standard deviation, with "3" being the center of the bell curve. For IQ, in so far as you use that to measure intelligence and consider it a decent proxy for the LOGIC stat, this means a 3 is a character with an IQ between roughly 85 and 115.
Logic 3 covers most normal humans. At the high end you would be expected to happily graduate college in the modern US, at the low end you would make it through high school...probably
A logic 2 then might be an IQ of 75-85. (The curve isn't perfect, blame the inventors.) You're getting in the range where you flunking out of high school in the modern US is getting be to a significant risk. A lot of time you "just don't get it" when concepts more basic than arithmetic and basic literacy. Not because you're lazy, but because you lack the requisite processing power. Even those basic life skills you find slow and frustrating because everyone else seems to grasp things so much more easily than you.
A logic 1 character has a sub 75 IQ. This doesn't mean your character is considered intellectually handicapped, but you'd be a candidate for special education in the most states education system. You can be expected to perform unskilled labor just fine; you meet all the standards for simple factory work or manual agriculture for instance, and could even live an ok life, but you are definitely not very well equipped to handle modern life and things like numeracy in all but the most rote circumstances.
To which you might reply "ahh! Logic 1 sounds almost unplayable! And there's no point in having an unplayable stat!" Well, it's playable, representing a truly intellectually disadvantaged person trying to make their way in a dystopian world., not just "cutesy dumb." Alternatively, you could cheat the curve and only use a 1/2 SD downgrade per point below 3, which would then basically make you an 85ish IQ.
You would have to decide if Party Girl is a Party Girl because she is really quite dumb and has turned to the rock/drugs/sex lifestyle because it offers something she can be good at and people seem to appreciate her for or whatnot 0\- Logic 1 - or if she is perfectly normal functioning human who just chose a different path - logic 3.