4. Why would your own personal study be less biased than a test? You're deciding what parts of the reading you focus on, what data from your personal life you put into it, and so on. In a test at least you can try to standardize the data.
One important reason, I think, is that the cognitive functions are far more agnostic as regards
social value.
You're likely to have a lot of subjective bias when a particular trait is perceived to be more valuable than another. Let's take the example of a question supposed to measure Extraversion vs. Introversion: "I'm comfortable with speaking in public". If there is bias, it's almost certainly going to be towards wanting to be more (rather than less) comfortable with public speaking. Because extroversion tends to be more socially valued than introversion (though that depends on the country to some extent). But if the phenomenon were reversed, notice we would have exactly the same problem.
Now take another question supposed to measure Intuition vs. Sensing: "I am really interested in reading and ideas". How likely is it that someone will be biased towards being
not interested in reading and ideas? Probably not very likely. Once again, being a person with "a lot of ideas" is more socially valued than the reverse. Once again, however, if the phenomenon were reversed, we would have the same problem.
You can apply this to a myriad of traits supposed to be captured by the test questions. The core issue here is that 'extroversion', 'introversion', 'feeling,' 'thinking', 'intuition', etc. are not value-neutral terms. This is, among other things, what injects bias into the internal mechanism of the test.
It's quite different when you study the functions. Now extroversion is no longer about you as a whole person, it's about your
intuition, or your
feeling, or whatever. This displaces the valuation into the realm of the functional, rather than the social; and it is also clear from the beginning that everyone has both introverted and extroverted functions, feeling and thinking functions, etc. You're no longer 'a feeler', rather you have e.g. introverted feeling; as well as extroverted thinking, and so on. The study of the functions makes it much more clear that they capture how you operate at a certain level; they don't capture what you are.
Of course this is never going to be completely free from bias. Some people think Ne is better than Ni, or better than Se; others think Fi is better than Fe; etc. But the displacement of the traits away from the ego and towards the functions of the ego, is a significant leap towards mitigating for bias. It's probably much easier for a shy person in, for instance, a very extroverted society to agree that they are e.g. Ni dominant than to agree that they are "introverts".
