Nub theory?

Is the nub theory AKA "angle of the dangle theory" correct? They say that if your baby's nub lays at an angle of 30degrees or less it's a girl, but if it points straight up its probably a boy. Was this  true in your case? On my latest ultrasound the nub was pointing straight up which makes me think it's a boy! Just wondering if this was true for anyone? I've got a picture to show what I'm talking about x