Personality Tests: MBTI vs. Big Five, Validity and Use

Name: Are Personality Tests Accurate? This One Is & Here's Why You Should Do It
Uploaded: 2019-07-06T15:00:00+00:00
Duration: 11 min 23 s
Channel: Med School Insiders
Description: Summary and key takeaways on Personality Tests: MBTI vs. Big Five, Validity and Use, covering Origins of Personality Testing Personality assessments first

Med School Insiders

Jul 06, 2019

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11 min video

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2 min read

YouTube video ID: 1ycNtfy1f34

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Personality assessments first appeared as tools for personnel selection in the armed forces. Early developers aimed to identify soldiers best suited for flying military aircraft. Most of these early tests reflected the creators’ subjective feelings rather than rigorous scientific protocols.

The Myers‑Briggs Type Indicator (MBTI)

Isabel Myers and Katharine Briggs created the MBTI without formal training in psychology. The instrument measures four pairs of opposing preferences—Extraversion/Introversion, Sensing/Intuition, Thinking/Feeling, and Judging/Perceiving—and combines them into 16 distinct personality types. Its binary, easy‑to‑understand structure and the “tribal” identity it offers explain the test’s widespread popularity. Critics note that “the insights of the MBTI are comparable to tarot cards or palm reading,” and that “most personality tests tell us less about the individuals who take them and more about the individuals who devised them.”

The Big Five and HEXACO Models

Scientists developed the Big Five by compiling every possible personality‑related word, constructing questionnaire items, and applying statistical clustering to reveal five coherent dimensions: Extraversion, Conscientiousness, Agreeableness, Neuroticism, and Openness to experience. HEXACO extends this framework with a sixth factor, honesty‑humility. Unlike the MBTI’s forced binaries, these models place individuals along continuous spectra, offering a more nuanced portrait of personality.

Scientific Standards: Validity and Reliability

Validity describes how well a test measures what it claims to measure; reliability indicates whether the test yields consistent results over repeated administrations. The MBTI scores poorly on both fronts. Retest studies report that 24–61 % of participants receive different type results, with one study showing 50 % changing after only five weeks. Moreover, the MBTI omits emotional stability and treats “thinking” and “feeling” as mutually exclusive, further undermining its scientific credibility.

The Utility of Self‑Reflection

Even with limited predictive power, personality tests can serve as conversation starters and tools for introspection. They help individuals spot blind spots and recognize strengths. True personal growth, however, often stems from external feedback from friends and family rather than test results alone. Genetics accounts for roughly 40 % of personality variation, while the remaining 60 % derives from environmental influences. As one speaker put it, “a personality test can only tell you what you tell it,” and “you have far greater power over your own personality than you’d expect.”

Takeaways

Early personality assessments were created for military personnel selection and relied on developers’ intuition rather than scientific methods.
The MBTI, built by Isabel Myers and Katharine Briggs without formal psychology training, assigns people to 16 binary types, a design that fuels popular “tribal” identity but scores poorly on validity and reliability.
Scientific models such as the Big Five and HEXACO emerge from statistical clustering of trait descriptors, producing five or six dimensions that reflect continuous spectra rather than forced binaries.
Validity measures whether a test assesses its intended construct, while reliability gauges consistency; MBTI retest studies show 24–61% of users receive different results, indicating weak reliability.
Personality tests can spark self‑reflection and highlight blind spots, yet lasting growth depends more on external feedback, and genetics accounts for roughly 40% of personality while the environment contributes the remaining 60%.

Frequently Asked Questions

Why does the MBTI perform poorly on validity and reliability?

The MBTI forces binary choices and was not built using empirical methods, so it fails to capture trait continuums. Retest studies show 24–61% of users receive different type results, and the test omits emotional stability, leading to low validity and inconsistent scores.

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Helpful resources related to this video

If you want to practice or explore the concepts discussed in the video, these commonly used tools may help.

The Big Five Personality Traits Book Recommended

Provides a scientifically rigorous alternative to popular personality tests, helping the reader understand personality through the lens of empirical psychology.

Amazon →

Journal For Self Reflection And Introspection

Facilitates the speaker's recommendation of using introspection and external feedback to identify personal strengths and blindspots.

Amazon →

Books On Psychology Of Personality Development

Explores the nature vs. nurture debate and how personality traits are formed, supporting the speaker's point about the 40/60 genetic-environmental split.

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Full Transcript YouTube

Are you an INFP or an ESTJ?
What about your Minnesota Multiphasic results,
or how did you do on your Rorschach test?
The Big Five?
There are dozens of personality tests and
assessments with varying degrees of utility.
Which tests are backed by science, and which
tests are more entertaining than helpful?
Let’s find out.
Dr. Jubbal, MedSchoolInsiders.com.
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While personality assessments and tests have
blown up in the past century, they originated
for a simple purpose – help with personnel
selection in the armed forces.
More specifically, the developers of these
tests hoped that by studying personality and
potential mental health issues, one would
be better able to determine which soldiers
were better or worse suited to fly military
aircraft.
Since then, dozens of personality assessments
have emerged, each with a different theory
on personality and how to best describe it.
Our understanding of personality and models
to describe and approximate it are purely
human inventions, not concrete sciences.
Each system has its own language and ideology,
theories and philosophies in determining which
traits are determinative and how to go about
assessing them.
How should we categorize traits?
Are they binary or plotted along a bell curve?
While seemingly based in science, few have
truly followed any resemblance of the scientific
method.
In fact, most assessments were built on the
creators’ subjective feelings about personality,
rather than rigorous scientific protocols.
For that reason, most personality tests tell
us less about the individuals who take them
and more about the individuals who devised
them.
For example, Hermann Rorschach was the Swiss
psychiatrist who turned a parlor game into
the iconic inkblot test.
Starke Hathaway was a Midwestern psychologist
who found it important to ask questions about
religious beliefs, sex life, and bathroom
habits in his Minnesota Multiphasic Personality
Inventory, or MMPI for short.
If you’ve gotten to your psych rotation
in medical school, you’ve likely heard of
the MMPI-2.
And of course, there’s Isabel Myers and
Katharine Briggs, the mother-daughter housewife
duo who studied Carl Jung’s texts and were
inspired to create a personality test despite
having zero background, training, or credentials
in anything psych related.
Myers and Briggs are credited for creating
the all too famous Myers Briggs Type Indicator,
or MBTI for short.
According to CPP, the publisher of the MBTI,
it “measures four pairs of opposing preferences,
which are inborn and value-neutral, to form
a person’s four-letter type.”
The assessment discerns between “Extraversion
(E) or Introversion (I),” “Sensing (S)
or Intuition (N),” “Thinking (T) or Feeling
(F),” and Judging (J) or Perceiving (P),”
resulting in 16 different personality types,
like ENFP or ISTJ.
A few decades after the birth of the MBTI, a group
of scientists began developing what would
become the Big 5 Personality Traits, or the
5-Factor Model.
Rather than relying on their intuition to
select criteria for their test, they compiled
every word that could be considered a personality
trait and created simple questions about them.
For example, on a scale of 1 to 5, would you
say you get upset easily?
Do you follow a schedule?
Based on these answers, the statisticians
grouped traits that seemed to cluster together,
such as talkative and sociable, in to five
basic categories: Extraversion, Conscientiousness,
Agreeableness, Neuroticism, and Openness to
experience.
Chances are that you’ve heard of Myers Briggs,
but maybe you weren’t aware of the Big 5
or its more recent derivative, the HEXACO
test.
Why is that?
Some suggest its because of the thousands
of people who have invested time and money
in becoming MBTI-certified trainers and coaches.
Others say it’s because the test focuses
only on the positive and therefore it seduces
test takers with an image of their own ideal
self.
I argue that the biggest reason for its success
is the neatly organized and binary manner
of the test.
There are four categories, each with a binary
option.
It’s easy to comprehend, easy to explain,
and you’re able to readily identify with
one of 16 tribes.
As as humans, we love our tribes.
Other personality tests, on the other hand,
are not binary and are more of a continuum,
which is less entertaining, less easily understood,
and less sexy.
But unfortunately for the Myers Briggs Type
Indicator, people and their personalities
are not binary, but are much more on a continuum.
You’re not a pure introvert or a pure extrovert,
but usually somewhere in the middle.
The insights of the MBTI are comparable to
tarot cards or palm reading – being generic
enough such that when you read your description,
you can certainly identify with parts of it,
but it’s not a truly accurate and comprehensive
depiction of who you really are.
When scientists look at such personality tests
and assessments, two primary elements come
to mind – validity and reliability.
Validity is a measure of how well a test measures
what it claims to measure.
Within validity, there are different types,
such as content validity, criterion-related
validity, construct validity, and face validity.
Reliability is a measure of whether the test
reliably indicates accurate results, meaning
you would get the same results if you took
the test more than once.
Unfortunately for the MBTI, it receives piss
poor scores on both fronts.
In one study, researchers found that 50 percent
of people received different results the second
time they took the test, even just five weeks
later.
Other studies have found similar results ranging
from 24-61% of people receiving different
results when taking the test multiple times.
The MBTI misses the mark in a few other ways,
including one key element of personality – emotional
stability versus reactivity, meaning the tendency
to stay calm and collected under stress or
pressure.
This is one of the most important predictors
of individual and group patterns of thought,
feeling, and action.
The judging-perceiving scale reflects whether
the test taker is more of a planner or the
spontaneous type, but it overlooks the industriousness
and achievement drive that accompany these
characteristics.
Together, they form a personality trait called
conscientiousness.
Lastly, in the binary system of the MBTI,
traits are mutually exclusive.
For example, under this model, thinking and
feeling are on opposite ends of a single spectrum,
meaning that if you are drawn to ideas and
data, you cannot also have a preference for
people and emotions.
But research has demonstrated the exact opposite,
that people with stronger thinking and reasoning
skills usually also demonstrate better emotional
intelligence, being able to recognize, understand,
and manage emotions.
While it’s a sad story for MBTI, there’s
good news for the Big Five.
The test was shaped by an empirical process
and while not perfect, most studies since
have demonstrated more acceptable levels of
validity and reproducibility.
So far, studies have demonstrated considerable
power in predicting job performance and team
effectiveness.
Some researchers have even mapped the big
five to relevant brain regions.
And while the Big Five model is far from perfect,
there’s growing support for a HEXACO model
of personality, which is essentially the Big
Five with an addition of a sixth trait: honesty-humility.
Despite the Big Five being far superior than
Myers Briggs from a scientific validity and
reproducibility standpoint, I don’t think
it will catch on, at least for lay people.
It’s just more catchy and easier to say
you’re an INTP than saying you’re 56%
on openness and 35% on neuroticism.
People sometimes expect personality tests
to tell them some hidden secrets to their
character.
But the truth is that a personality test can
only tell you what you tell it.
Accuracy with the test is entirely based on
how honest and self-reflective you are with
your answers.
If I told the test that I’m a super patient
and one to readily forgive, it would sure
make me feel good, but I would just be lying
to myself.
But I’d argue there’s still utility to
personality tests, even if they’re all far
from perfect.
And sure, entertainment should be one of the
top reasons.
Let’s be real, including your Myers Briggs
on your online dating profile makes for a
good conversation starter.
The real utility is in that it facilitates
the process of introspection and reflection.
Taking a personality assessment helps someone
consider some of their strengths and weaknesses,
and begin having some important but difficult conversations.
The most insightful realizations I’ve had
in my own behavior, in my own ways of possible
growth, wasn’t from seeing the results of
a personality test, but from speaking with
close friends and family about areas of improvement.
A personality assessment is by no means a prerequisite,
but it can definitely help you get started.
For those who are newer to self-reflection,
personality tests can help you consider possible
blindspots.
While Gretchen Rubin’s Four Tendencies is
far from a perfect model, it helps one consider
what external and internal factors motivate
them to behave in certain ways.
I even made a video applying her model to
student life, helping you determine how to
understand your personality tendency and use
a variety of strategies and hacks to force
yourself into being a better student based
on that tendency.
Now were the four tendencies a scientifically valid and reproducible model?
The data is lacking, and I wouldn’t put
my money on it, but hundreds of comments from
students who successfully implemented and
improved their performance is good enough
for me.
Other critics are quick to stay that your
personality is fixed and resistance is futile.
It’s a waste of effort.
Why even try to change or improve yourself?
Speaking from personal experience, I’d say
you have far greater power over your own personality
than you’d expect.
It’s just that most people fail to make
any significant changes because they don’t
put in the proper effort in changing their
systems.
In fact, a recent meta-analysis demonstrated
that approximately 40% of a person’s personality
is due to genetic influence, while 60% can
be attributed to environmental effects.
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