reckful
New member
- Joined
- Jul 6, 2013
- Messages
- 656
- MBTI Type
- INTJ
- Enneagram
- 5
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.
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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.