Astrology isn't causal guys, it gives an understanding of resources available to people not outcome, hence people may have the agression to be an axe murderer, but choose to use that agression to promote world peace... ultimately all astrology can say is you have the agression as an oporuntunity in the first place.
As for evidence MBTI ought to be provable, it's only a segmentation albeit preference reporting, it can be impeirically tests for significant differences but has not.
test of Astrology can only be done at a rather crude level because, like psycology (which is basically human and their behaviour at complex) are too diverse, it would be easier to test astrological princiaps like humours against behaviour and measure the retrofit.
Ie % spent on communications (net, mobile, landline) and degree of coleric (with the eception of b2b dialogues - which would be melancolic)... that is a stutably big behaviour.
All in all guys astrology is NOT causal - which is a misunderstanding... guys we are off topic, this was suppose to collate information for the OP not yet another banter about validity...