There is obscurity between MBTI/Keirsey and socionics and their correlation precisely because people are attempting to correlate them. In reality, if the correct way is approached and utilised, there will be no need for correlation.
If you scroll down on this page, you will find a table with the headings "Ego functions", "Formal name", "Social role", "Person" and "MBTI type". Now, when I look at that table, I can only assume - as any newcomer or beginner might do - that if I already know my MBTI/Keirsey type, I will find that it conveniently corresponds to my socionics type, so that I can find out more about myself and the socionics theory.
So, I come on the page, and I look at ENTJ. Now, thanks to my knowledge of MBTI/Keirsey, I know that the ENTJ's functions are:
* Dominant Extroverted Thinking (Te)
* Auxiliary Introverted Intuition (Ni)
* Tertiary Extroverted Sensing (Se)
* Inferior Introverted Feeling (Fi)
Then I think to myself 'maybe the functions don't correspond with socionics types. Maybe the ENTj in socionics has a different functioning order to that of MBTI/Keirsey. So, I look at the LIE's functions and how they correspond with MBTI/Keirsey functions of the ENTJ on the aptly named Wikisocion:
* 1st function
* 2nd function
* 6th function
* 5th function
And look! The first two functions are exactly the same! To check my calculations, I take another example. The ESFP of MBTI/Keirsey:
* Dominant Extroverted Sensing (Se)
* Auxiliary Introverted Feeling (Fi)
* Tertiary Extroverted Thinking (Te)
* Inferior Introverted Intuition (Ni)
I then compare it to the SEE:
* 1st function
* 2nd function
* 6th function
* 5th function
The same pattern emerges. It seems that socionics type clearly correlates with MBTI type. And for future reference, I know that MBTI/Keirsey ENTJ is definitely, and can only be, LIE in socionics and that MBTI/Keirsey ESFP is definitely and can only be socionics SEE. It is an indubitable truth. ENTJ = LIE and ESFP = SEE, and no one can tell you otherwise. It is fair to say that one can use ENTj/ENTJ/LIE interchangeably, and it wouldn't matter, because they mean exactly the same thing. The same can be done with the ESFP/ESFp/SEE.
Can this be done with all types? Now, since I've tried two types with an Extraverted leading function, to double check calculations I'll use an Introverted type; the INTJ. So, using the same method, MBTI/Keirsey INTJ's functions are as follows:
* Dominant Introverted Intuition
* Auxiliary Extroverted Thinking
* Tertiary Introverted Feeling
* Inferior Extroverted Sensing
I now look at the apparent socionics equivalent, LII, and its functional ordering:
* 8th function
* 7th function
* 3rd function
* 4th function
But oh shit. This can't be right. It doesn't follow on from my previous reasoning. So I begin to trawl through the types to find the type that DOES fit the original functional ordering that I found within the LIE/ENTj and the . Finally I find it. Yes, it's LII's irrational friend, ILI. And guess what the functional ordering is? That's right:
* 1st function
* 2nd function
* 6th function
* 5th function
Just by chance, to see if another Introverted MBTI type might follow the same patter as the INTJ, I use the ISFP. It's functional ordering in MBTI:
* Dominant Introverted Feeling
* Auxiliary Extroverted Sensing
* Tertiary Introverted iNtuition
* Inferior Extroverted Thinking
And its socionics equivalent SEI's functional ordering? It's:
* 8th function
* 7th function
* 3rd function
* 4th function
Interesting. It follows the same patter as the INTJ of MBTI. So, to find out what the ISFP is in socionics, I'll use the same method as I did with the INTJ, which leads me to ISFj, or ESI. And what do you know:
* 1st function
* 2nd function
* 6th function
* 5th function
Interesting. So, it seems that INTJ and ISFP have become INTp and ISFj when they are seen from the point of view of their socionics counterparts, despite the fact that ENTJ and ESFP retain their functional ordering from whichever point of view you look at it.
Why is this the case? Why is it that the MBTI ISFP becomes and ISFj rather than staying as an ISFp? Why, when I saw that table, couldn't - or rather wasn't - ISFp at the end of the table on the row that matched up to "Fi Se ESI (ethical sensory introvert) Conservator / Guardian Dreiser"? Why was it on the row that had "Si Fe SEI (sensory ethical introvert) Mediator / Peacemaker Dumas" on? Where's the logic in that? Surely the latter should have corresponded to ISFj and not ISFp, as it did. And more fundamentally, why is there no logical consistency in something that need not be correlated because it should naturally follow but doesn't (i.e. why is ENTJ LIE, ESFP SEE, but ISFP NOT ESI)?