I've known I was an ISTJ on the Meyers Briggs scale for quite sometime. But everytime I come across a new version of the quiz on - line , I try it out to see if I have changed. I'm so high on the scale on each of my traits that I think it would take A LOT to move me over to one of the other traits. You can read more about it here.
Portrait of an ISTJ - Introverted Sensing Thinking Judging
(Introverted Sensing with Extraverted Thinking)
You can click here to take a super quick version of it.