The traditional MBTI is binary. Each letter is a black-and-white either-or. This pushes people into 16 rather rigid boxes, and there is no way to differentiate people within the same box.
Some MBTI tests report percentages. This allows a variation for each letter. However, little is published regarding how to interpret the percentages.
The E/I percentage describes the relative strengths between dominant and auxiliary functions, and between tertiary and inferior functions. For example, in the case of an INTP, if the I percentage is 100%, then Ti is truly the dominant function and differentiates significantly from Ne being the auxiliary function. However, if the I percentage is 51%, then Ti and Ne are about equally strong as leading functions.
The N/S percentage describes the relative strengths between the sensing and intuitive functions. Again, a 100% rating is easy to understand. What if it is a 75/25% split for an INTP?
At 100%, this means Ne is the auxiliary function. With a 75/25% split, it means it is a 0.75Ne + 0.25Se split. Instead of purely theoretical, this individual also likes the thrill of doing something exciting, just less often. This also means the tertiary Si is also split as 0.75Si + 0.25Ni, mostly memory based, but also has some insight.
This is a thinking/feeling split. For an INTP, 100% means pure thinking. A 75% T means 0.75Ti + 0.25Fi. This means most of the time decisions are based on internal logic, but occasionally decisions are based on personal/internal values and beliefs.
This one is the trickiest. J/P is based on the extroverted function of the dominant and auxiliary functions. There is some interaction between the J/P and E/I split.
The J/P letter indicates how a person is seen from the outside. If Fe/Te is strong, then the person is seen as judging. On the other hand, if Se/Ne is strong, then person is seen as perceiving.
We can see how the E/I split can easily make a person appear more or less judging/perceiving. For example, if an INTP/ENTP mix has a 50/50 split of E/I, then the Ti and Ne functions are equally strong. However, the person is still seen as perceiving because of Ne.
In order to have a J/P gradient, we need to include the same functions but with opposite energy. For example, in the case of an INTP, a 75/25% split of P means the perceiving auxiliary function is 0.75 extraverted and 0.25 introverted. But this also affects all of the other functions of the stack.
We will have an idealized model based on how conscious a person is. Dominant is a 3, auxiliary is a 2, tertiary is a 1 and inferior is a 0.
Next, we introduce the concept of a function mix for each consciousness level. This can be a mix of up to four functions.
To work out of the numbers, here is the procedure:
Then the weighted average of each function times the level can be calculated. In this case:
Now we sort the functions based on the weighted values:
We can now see in this particular individual, Ti and Ne truly leads the other functions. Se, Te, Si and Ni are all ranked about the same, with Fe and Fi being significantly lower than the rest.