Why believe me, right? It's a very subjective exercise, in general. There is no scientific method. I find a lot of people see what they want to see in others, they self-identify without being objective or don't look for the 'patterns' inherent in how types present in the whole of society...I've been doing this out of self-interest for over 20 years now. I've come to a very deep understanding through objective observation of individuals, and how they appear and function/behave in larger society, and how they couple with other types. That might sound super arrogant to you, or it might explain why believe I am correct.
Also, I find that a lot of people mistake 'humanism', and 'empathy' as 'N' or 'F' qualities, when really, it's just a very well-adjusted and articulate ISTJ