I groupings I already know of (though I don't know how legitimate the groupings are):

EJ-IJ-EP-IP--supposedly developmentally evident

ES-IS-EN-IN--learning style related, I believe

SF-ST-NF-NT--Mind types

SJ-SP-NF-NT--Kiersey's Temperaments

SJ-SP-NJ-NP--Perception orientation

FJ-FP-TJ-TP--Judgement orientation

{EN_J, EST_}-{IN_J,IST_}-{EN_P,ESF_}-{IN_P,ISF_}--Berens' Interaction Styles

So what's one more grouping?

I know my thinking isn't the clearest right now...

But with 16 types that you want to divide into 4 groups of 4, I believe there will be 16!/(4!)^5=2627625 ways to do that.

**Over two million groupings**--that seems like a big number, I'll explain how I got it below (please correct my thinking, if you spot an error).

Two way to think of it:

1) Think of 16 slots in the following diagram:

|****|****|****|****|

There are 16! ways to place the types into the slots designated by the stars. But of course, for groupings, it does not matter if you switch the order of types between the bars, so divide by (4!)^4. It also doesn't matter if you reorder the groups, so divide by another 4!, yielding 16!/(4!)^5.

2) Lets say you arbitrarily had a representative of each type to pick a letter out of a hat. In the hat, there are 4 red, 4 green, 4 blue, and 4 yellow cards. After each representative has picked a card, we will have 4 groups of 4, based on color. There are 16!/(4!)^4 ways this could happen. But of course, it is arbitrary what color the group is, so divide again by 4! yielding 16!/(4!)^5.

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Though I guess, we can restrict to "Kiersey-like" groupings. By this, I mean first we choose a dichotomy (Kiersey chose S-N, Cimarron chose J-P), make a split, then choose a dichotomy to split the first group, and another dichotomy for the second group.

There are 4 dichotomies for the first choice, 3 dichotomies left for the second, and 2 dichotomies for the third choice, yeilding 4*3*2=

**24 "Kiersey-like" groupings. **
Possibilities:

- ES-EN;IF-IT
- ES-EN;IJ-IP
- EF-ET;IS-IN
- EF-ET;IJ-IP
- EJ-EP;IS-IN
- EJ-EP;IF-IT

- IS-ES;NF-NT
- IS-ES;NJ-NP
- SF-ST;EN-IN
- SF-ST;NJ-NP
- SJ-SP;EN-IN
- SJ-SP;NF-NT--Keirsey

- EF-IF;ST-NT
- EF-IF;SP-NP
- SF-NF;ET-IT
- SF-NF;TJ-TP
- FJ-FP;ET-IT
- FJ-FP;ST-NT

- EJ-IJ;SP-NP
- EJ-IJ;FP-TP
- SJ-NJ;EP-IP
- SJ-NJ;FP-TP
- FJ-TJ;EP-IP
- FJ-TJ;SP-NP--Cimarron

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With that said, only Cimarron's can be based on a verbal parsing of the dichotomies. Only "Judging" vs. "Perceiving" verbally selects a second dichotomy to split each group.

I don't like "Dreamer" as characterization of NPs, however. Though I do have dreams, "Dreamer" seems a bit derogatory.