I have created an MBTI personality inventory based on personality types considered as whole types and not as combinations of letters or functions. In this endeavor, I've come up with a 112-question inventory which I consider to be still in its alpha stages. The only person who has taken this test thus far is my wife (ISFP?).
Intuitively, my wife seems like an ISFP. She is Introverted (a wallflower at parties, she does better with one-on-one situations, etc.), Sensing (she doesn't care for deep subjects but prefers superficial stimulation), Feeling (she's a people person), and Perceiving (care-free lifestyle, etc).
In function terms, she is Fi because she has formed her own values, and Se fun-loving. But which function is dominant, which is auxiliary, and how is this proven? Nobody seems to know.
While my test obviously needs some work, here are my wife's top results:
In about 8th place was ISFP.
The SFP and STP characteristics kind of match my overall intuition of my wife's type, along with a certain level of J that probably comes from Fi. She scored surprisingly extraverted for an introvert. But my test takes no notice of extraversion or introversion.
Still, it indicates that my wife is only moderately interested in ISFP things, which is what I expected. And she doesn't really fit into any single type anyway. I was hoping she would score highest in ISFP, but that was just to confirm my own bias. I know that, despite her being an introvert with sensing, feeling, and perceiving characteristics, along with strong Fi and Se, ISFP doesn't provide the best description. Probably nothing does.