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Reconciling MBTI with Big 5

reckful

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At issue is the intrinsic difference between between reliability and validity. What your OP demonstrates is reliability, but as Hard points out, it fails to demonstrate validity. A handy analogy is the old joke about the drunk looking for his keys, where the drunk is looking for his keys under the streetlight, even though he knows he dropped his keys over there in that dark corner. Looking in the dark corner would be valid, but unreliable, as it is difficult to get results from the corner. Looking under the streetlight is reliable, but invalid, because we know that the keys weren't dropped near there. We could feel around in the dark corner, find a jingly metal object that feels like keys, but (in this analogy), there would be nothing to publish a paper about, because we have no light here to prove that we actually found the keys. We would "know" that they were the drunk's keys, because we know what "keys" feel like and it isn't likely that there are someone else's keys here, but "it feels like keys" isn't good enough for those who need a reliable light on the subject.

This is not to say that MBTI or Big Five are invalid, only that their similarity does not lead to the conclusion that they are valid.
...
We need both reliability AND validity, in order to truly know what is true or not. In the soft sciences, we often tend to have either one or the other, but rarely both. (If we could get both, then they'd not really be soft sciences any more.)

It sounds like you somewhat misunderstand what "reliability" is about in the personality typology field. It involves something called "internal consistency" (which is basically whether the test items that purport to be tapping into the same preference cluster together reasonably well), and test-retest reliability.

And "validity," as I noted in an earlier post, basically has to do with whether the theoretical constructs are found to significantly correlate with real-world stuff that goes beyond the specific things that the applicable test asked the subjects about.

And among the things that a personality dimension can correlate with as evidence of its validity is dimensions on other personality typologies — assuming it's not a case where the two typologies' tests are basically asking the same questions. So it could at least theoretically be the case — as LION4!5 suggested — that the correlation between the Big Five and the MBTI offered supporting evidence for the validity of both (although that would be undercut to the extent that the actual content of the test items overlapped).

If you're interested, you can read more about reliability and validity (as applied to the MBTI specifically) here:

MBTI Form M Manual Supplement

And you'll note that the Validity section of the document is where you'll find the studies that correlate the MBTI with several other personality typologies.

As a final point, a personality typology can demonstrate excellent reliability and validity both, but that doesn't make it a "hard science" by most definitions (although you might say it makes it "less soft"). Because the personality/behavioral/etc. things that personality typologies deal with are mostly things where the type stuff is just one among many possible influences, even a highly reliable and valid personality typology can't be used to make specific and falsifiable predictions about, e.g., what a given person is going to do in a given situation.

Like many of the soft sciences (including, e.g., economics), personality typologies can end up making reasonably good predictions when it comes to probabilities — e.g., a prediction that, if I start a personality-related internet forum, it will attract a lot more INs than ESs. But success with respect to those kinds of probabilistic predictions doesn't (by most definitions) shift economics or personality typologies into the "hard science" category.
 

Pionart

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You would expect I/E, F/T, N/S and rationality to be able to lie on a spectrum. J/P not so much since it refers to both top functions.
 

BlackDog

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There are issues where reasonable people can disagree and issues where there's a right and wrong, and this is one of the latter issues. Whether a personality dimension is capable of demonstrating psychometrically respectable "validity" and whether it's bimodal are independent issues.

I see no evidence to suggest that psychometrics is a respectable science. But, if it was, you can't deny that bimodality in the data would signify either that the data was corrupt, or it if was not that something other than randomness was at work.

As further discussed in the "Big Five is science and the MBTI is astrology" and "Real psychologists reject the MBTI" sections of this post, the dichotomy side of the MBTI can now point to decades of respectable data support, and McCrae and Costa (the leading Big Five psychologists) long ago acknowledged that the MBTI, besides effectively tapping into four of the Big Five factors, also passed muster in the reliability and validity departments.

Sure. McCrae and Costa had to do that or else they would have had to scrap their own supposedly superior system. But neither system corresponds to anything real. These are just correlations. Description, not explanation.

And the Big Five dimensions also have decades of respectable support for their validity.

And that's without either the Big Five or MBTI dimensions demonstrating a bimodal distribution.

The FFM only claims to be measuring degrees of one construct, so we would not expect a bimodal distribution for FFM. MBTI inserts two constructs without any justification whatsoever. If you are 60% you become 'T' instead of 'F'. The use of two constructs is unforgivable and unjustified.

"Validity" basically has to do with whether the theoretical constructs are found to significantly correlate with real-world stuff that goes beyond the specific things that the applicable test asked the subjects about. To the extent that a personality dimension demonstrates that, it has validity, regardless of what the shape of the distribution curve (in terms of weak and strong preferences) may turn out to be.

My definition of validity I explained somewhere else. Your definition cannot be satisfied by anything in a soft science.

In the spoiler are membership stats for TC and Personality Café. For each type, the first percentage is the percentage of that type at the forum, the second percentage (in parentheses) is the estimated "general population" percentage from the official MBTI folks (from this page), and the final number on the right is the self-selection ratio for that type — i.e., the ratio of the forum percentage to the general population percentage.

Assume for the sake of discussion that the relevant typings were all "official MBTI" typings. In that case, those would unquestionably be a strongly supportive set of results from the standpoint of the validity of the MBTI E/I and S/N dichotomies. The MBTI doesn't ask people if they use internet forums (or the internet), and it doesn't ask them if they're interested in personality (or psychology). But the type frequency pattern at both forums (involving relatively large samples) is almost perfectly in line with a type-related explanation that says that (1) an N preference has a very large impact on the likelihood that someone will participate in personality-related internet forums, and (2) introversion also has a substantial impact (but not as large as an N preference).

And as far as that validity support is concerned, the distribution curve of mild and strong preferences is irrelevant.

But I can't assume that. Those numbers and those 'type-related explanations' are insufficient. A type-related explanation can be generated for anything and everything; anyone who has worked with type on these forums knows that. Only if these explanations have predictive power are they valid, and I haven't seen them tested.

The Forer effect probably unbelievably warps perception of the types. It would not be surprising if the vast majority of people type as IN.

Having been on PerC myself, if you read the old threads you see that a huge number of people change type.

You brought up in your linked post how a retest change of type by just one letter counts as a fail, and treated this as if it gave the test more validity. It does the opposite. Type descriptions totally transform with the change of just one letter. That is the fundamental problem and error of having types at all; there is tremendous pressure to 'be' one type or another, whereas few people are 'one type'.

Unlike the Big Five, which measures degrees of one trait, MBTI introduces radical divides on a spectrum which are not justified.

There is no good reason to think that people can judge their own character, beyond this, which calls all personality tests into question. Even if people did test and retest consistently, this does not mean that others would sort them the same way. I know this from my own experience, as well as conceptually.
 

BlackDog

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[MENTION=20829]Hard[/MENTION], I'm definitely tracking with your logic. Just because they match does not mean they are both correct. They could be wrong, or mis-measuring the same thing. All of my Psych professors HATE the MBTI. They don't think it's valid, or internally consistent. None of them are terribly keen on any personality inventories for the same reason.

Do your Psych professors have anything else to offer? Because as far as I was aware, the Big 5 is as ambitious a categorizer as exists in modern psych. If psych has simply given up on measuring something like personality then that makes sense as well, but if the Big 5 is still the best they have to offer, then I think my definition of validity as it relates to personality inventories is right. That may well be a good reason to reject personality inventories period . . . is that what you are saying at the end?
 

reckful

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But I can't assume that. Those numbers and those 'type-related explanations' are insufficient. A type-related explanation can be generated for anything and everything; anyone who has worked with type on these forums knows that. Only if these explanations have predictive power are they valid, and I haven't seen them tested.

Wow, LION4!5. Do you really not understand what "assume for the sake of discussion" means? I could care less what you think about whether the Big Five and MBTI are sufficiently supported at this point in the validity department. That's well established as far as I'm concerned, and I've discussed the reasons why (with supporting links) in other threads.

That was not the issue under discussion in that "assume for the sake of discussion" paragraph. That paragraph related to the main point of my post, which involved correcting your misunderstanding that the validity of the MBTI was somehow tied to the shape of the distribution curve.

As I said, that is not a matter on which reasonable people can disagree, and my post explained why.
 

BlackDog

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Wow, LION4!5. Do you really not understand what "assume for the sake of discussion" means? I could care less what you think about whether the Big Five and MBTI are sufficiently supported at this point in the validity department. That's well established as far as I'm concerned, and I've discussed the reasons why (with supporting links) in other threads.

That was not the issue under discussion in that "assume for the sake of discussion" paragraph. That paragraph related to the main point of my post, which involved correcting your misunderstanding that the validity of the MBTI was somehow tied to the shape of the distribution curve.

As I said, that is not a matter on which reasonable people can disagree, and my post explained why.

I was expanding the scope of the post. I had already dismissed the argument that the validity of MBTI was not tied to the shape of the distribution curve. As I said before, you have absolutely no reason to argue for dichotomies based on a normal distribution. It doesn't refute it, I agree, but it also doesn't support it.

I suggested that if the converse was true, that would be evidence for the dichotomies. The absence, by its silence, suggests that they are superfluous.
 

Little_Sticks

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I remember looking into Big 5 because everyone was saying how it put things on a curve and was somehow more accurate. But it seems to measure the same dichotomies with the exception of neuroticism.

O; Openness to experience: (inventive/curious vs. consistent/cautious) - Some argue this is an N/S divide in disguise
C; Conscientiousness: (efficient/organized vs. easy-going/careless) - This is covered under P/J in MBTI
E; Extraversion: (outgoing/energetic vs. solitary/reserved) - obviously MBTI related I/E
A; Agreeableness: (friendly/compassionate vs. analytical/detached) - T/F in MBTI
N; Neuroticism: (sensitive/nervous vs. secure/confident) - Neurotic types

So it's not really anything special to me. The only real addition seems to be the neurotic component, so you could translate to MBTI and describe neurotic types from healthy ones. But then again, Jung covered that as well; so you could ditch MBTI and Big 5 and use Jung and get a more powerful theory to frame people in. Besides, typing isn't supposed to be easy. It requires a lot of awareness of how other people are, as well as a lot of self-awareness of your own nature. When that's missing the types don't really illuminate anything by themselves because they aren't supposed to define people, but give an intellectual framework to begin to understand someone's nature.
 

Showbread

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Do your Psych professors have anything else to offer? Because as far as I was aware, the Big 5 is as ambitious a categorizer as exists in modern psych. If psych has simply given up on measuring something like personality then that makes sense as well, but if the Big 5 is still the best they have to offer, then I think my definition of validity as it relates to personality inventories is right. That may well be a good reason to reject personality inventories period . . . is that what you are saying at the end?

Yeah, most of them are just generally not fond of personality inventories. The Big 5 is used in research way more often than the MBTI, probably because there are a lot less subtypes. It's essentially a sliding scale.
 

INTP

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Ya, I'm sure the real, underlying introverty thing that the MBTI E/I dimension is tapping into and the real, underlying introverty thing that the Big Five E/I dimension is tapping into are two different things.

Thank goodness we've got both typologies, eh? We wouldn't want to miss either of those introversions! :alttongue:

And the point is...

The fact that the MBTI and Big Five may differ significantly (and they do!) in the way they theoretically characterize what the dimensions are all about doesn't mean that, if you switch your focus from the theoretical level to the underlying-biology level, the real, underlying (and at least somewhat hardwired) personality dimensions the typologies are tapping into aren't the same.

McCrae and Costa (the leading Big Five psychologists) certainly think that's the case, and so do most respectable sources, as I understand it.

The only real underlying thing for psychology is the neurology which accounts for certain type of thought patterns, or well, you could go even deeper than neurology by looking at how your genes interact with the environment to create these certain types of neural networks which account for I/E. Some of these underlying "real things" are the same with both MBTI and big 5, as I/E is on eysencks model for example(which has really similar I/E to big 5). One example that has been studied on the eysencks model that most likely effects I/E of MBTI(, jungian and big 5) as well is that they found that extraverts send more signals towards visual cortex from other parts than whats coming from eyes and less out of it than introverts. It might sound backwards at first, but if you look at it this way: when the visual cortex gets signals elsewhere(than eyes) it is sort of creating expectation for perceptions and can more quickly adjust to what comes from the eyes because it allows for less processing from the other parts and the signal is "ready" faster for it to be processed consciously.
But then there are things in big 5 that are most likely tapping on different fundamentals, like in big 5 activity levels are seen as one subscale of E/I, while it is not on MBTI. However MBTIs I/E does correlate with this as well, but its more like extraverts are on average more active than introverts, rather than being one of the definitions of I/E. But big 5 looks more of the behavioristic side of things, while MBTI looks at cognitive side of things and defines I/E more based on cognitive aspects.

I think the problem with big 5 is that its based on adjectives.. If you werent aware of this, big 5 was made up from analyzing adjectives that say something about human character and then abstracting them to lowest possible number of scales that are different from each others and they ended up with 5 scales.

Ps. big 5 isnt a typology :D
 

reckful

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I think the problem with big 5 is that its based on adjectives.. If you werent aware of this, big 5 was made up from analyzing adjectives that say something about human character and then abstracting them to lowest possible number of scales that are different from each others and they ended up with 5 scales.

"Big Five" is an umbrella term for a bunch of different typologies (using that term in a broader sense than you apparently do) that gradually converged as personality psychologists came to something like a consensus that they were all basically tapping into the same underlying clusters. If you're tracing back the Big Five to find its various roots, somebody could certainly take the position that those lexical (word-based) studies deserve to be called the "original source," but that's just historical trivia at this point. The current umbrella "Big Five" is really a combination of a variety of different perspectives and bases — which is a good thing.

If you're interested, you can read more about the history of the Big Five here.
 

lunalum

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Recent studies have confirmed that the MBTI and Big 5 are testing the same thing. So the test must be valid, right?
I would say, yes, the MBTI and the Big 5 are both an attempt to get at the same thing (with the exception of the limbic/calm of the Big 5). But the approach is different, making what they ultimately come up with different. The original psychological types of Jung are way out in left field as the most abstract approach, MBTI is somewhere in the middle, and the Big 5 is almost completely behavioristic. They aren't similar enough in approach for one's "validity" to prove the validity of the other. Needless to say, I don't take the validity of the Big 5 very seriously.


On the other hand, it has also been demonstrated that the dichotomies don't exist; traits fall on a bell curve.

This is interpreted to mean that the dichotomous types cannot exist.

Well, even assuming the Big 5 approach is at all close to the mark, dichotomies could still exist. Each data point still falls to one side of the bell curve or the other.

I do believe a normal distribution to be accurate for this sort of thing.... for many people to be in the middle and not at the extremes of the preferences. Even cognitive type itself is often not that expressed, for the majority of people just a slight flavoring. But it's still a distinct flavoring.
 
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