Psychology9 min read8 July 2026

Why STAR Uses the Big Five and Not MBTI

The most popular personality test in the world is not the most accurate. Here's why that matters — and what we built instead.

David Chadderton
David Chadderton
Behavioural scientist · Creator of the STAR Framework

The most popular personality test in the world is not the most accurate. Here’s why that matters — and what we built instead.

There are two personality tests that dominate the world of human behaviour.

The first is the Myers-Briggs Type Indicator, or MBTI. It is the one most people have heard of. The one that tells you whether you’re an INTJ or an ESFP. The one that shows up in team-building workshops, LinkedIn bios, and dating app profiles. Two million people take it every year. Fifty million have taken it since the 1960s. It is, by any measure, the most famous personality test on the planet.

The second is the NEO Personality Inventory Revised, or NEO-PI-R. It is the one most researchers use. It measures the Big Five: Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism. It has 240 items, 30 facets, and four decades of empirical validation. It is the gold standard of personality assessment in academic psychology.

These two tests are not the same. They are not even close. And a major study published in 2023 — using nearly 10,000 working adults — shows exactly how far apart they are.

The Study

Adrian Furnham, one of the most prolific personality researchers in the world, published a study in SCIRP’s Psychology journal examining the relationship between the 30 NEO-PI-R facet scores and the four MBTI dimensions. The sample was large: 7,538 males and 1,949 females, all employed, average age 36, drawn from British assessment centres over a period of 10 to 16 years. This is not a student sample. This is the real world.

The findings were striking.

The MBTI’s Extraversion-Introversion dimension correlated with the Big Five’s Extraversion at r = .20. That means the two tests share about 4% of their variance on this dimension. Ninety-six percent of what one test measures, the other does not.

The MBTI’s Sensing-Intuition dimension correlated with Agreeableness at r = .05. That is barely above zero.

The MBTI’s Thinking-Feeling dimension correlated with Agreeableness at r = −.35. This was the strongest overlap in the study — and even here, the two tests share only about 12% of their variance.

The MBTI’s Judging-Perceiving dimension correlated with Openness at r = −.16. About 3% shared variance.

The factor analysis was even more revealing. When both tests were analysed together, they produced four factors — but the factors did not map onto each other. The MBTI and the Big Five occupied different regions of factor space. They are not two ways of measuring the same thing. They are measuring different aspects of personality.

What This Means

If you’ve ever taken the MBTI and felt that the result was… not quite right, this is probably why. The MBTI is not measuring what the Big Five measures. It is measuring something else — something less reliable, less nuanced, and less predictive of actual behaviour.

The problems with the MBTI are well-documented:

It converts continuous data into binary categories. You are either Extraverted or Introverted. Either Sensing or Intuitive. But most people are not extremes. They cluster in the middle of the distribution. The MBTI takes your score, chops it at the midpoint, and assigns you to a category. This is like saying anyone taller than 5’8” is “tall” and anyone shorter is “short.” You lose the nuance. You lose the data.

It misses Neuroticism entirely. The MBTI has no dimension for emotional stability or instability. This is not a minor omission. Neuroticism is the single strongest predictor of mental health outcomes, stress reactivity, and emotional behaviour. It is one of the most replicated findings in personality psychology. The MBTI simply does not measure it.

It is based on Jungian theory, not empirical evidence. The MBTI is “loosely based on Jungian theory,” as the study delicately puts it. Jung’s descriptions of personality types include traits that, empirically, do not covary. The MBTI includes a scale (Judging-Perceiving) that is not part of Jung’s original theory. The theoretical foundation is inconsistent, and the empirical validation is thin compared to the Big Five.

Its reliability is lower. The MBTI’s test-retest reliability is lower than the NEO-PI-R. People who take the MBTI twice, a few weeks apart, get different results at a rate that should concern anyone using the test for serious decisions.

Why STAR Uses the Big Five

The STAR Framework uses the Big Five (OCEAN) as its personality substrate — Level 2 of the psychological stack. This was not an arbitrary choice. It was a deliberate decision based on exactly the kind of evidence this study provides.

STAR is built on seven psychological theories. Each theory captures a different aspect of human behaviour. Together, they form an integrated architecture — a psychological stack that moves from universal biological drives at the base to applied professional archetypes at the top.

The seven pillars are:

  1. Self-Determination Theory (SDT) — The motivation engine. Autonomy, competence, relatedness.
  2. The Big Five (OCEAN) — The personality substrate. Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism.
  3. Dual Process Theory — The cognitive tempo. System 1 (fast, intuitive) and System 2 (slow, deliberate).
  4. Regulatory Focus Theory (RFT) — The directional compass. Promotion focus and prevention focus.
  5. Social Identity Theory (SIT) — The relational filter. Belonging, group identification, collective roles.
  6. Cognitive Bias Theory — The distortion filter. The systematic errors in human judgement.
  7. Appraisal Theory of Emotion — The emotional filter. How our evaluation of events generates our emotional states.

The Big Five sits at Level 2 because it captures the stable personality traits that shape how motivation, cognition, and emotion are expressed. It is the structural chassis of the system.

Why not MBTI? Because the evidence says so. This study, and the decades of research it builds on, demonstrates that:

STAR chose the instrument that works, not the instrument that’s popular.

The STAR Archetypes: Trait Thinking, Not Type Thinking

One of the most common criticisms of the MBTI is that it forces people into boxes. You are an INTJ. You are an ESFP. The type becomes an identity, and the identity becomes a constraint. People start describing themselves as their four letters, and the letters start limiting how they see themselves.

STAR’s archetypes work differently. They are blends, not categories.

The four primary types in STAR are:

Each person has a primary and a secondary type. The blend creates one of twelve archetypes:

This is trait thinking, not type thinking. The Inventive Pathfinder is not “an Adventurer” in the way that the MBTI would say someone “is an Extravert.” The Inventive Pathfinder is a person whose primary motivational orientation is autonomy, secondary orientation is competence, and the blend creates a specific profile: someone who builds new systems because the existing ones are not good enough.

The Big Five’s facet structure makes this possible. When Furnham’s study looked at the facet-level correlations between the MBTI and the NEO-PI-R, it found that MBTI dimensions correlate with specific facets within Big Five domains, not the domains as a whole. The Thinking-Feeling dimension correlated with Agreeableness’s Tendermindedness, Trust, and Altruism facets — but not equally with all six.

STAR’s archetypes are, in effect, facet-level profiles. They capture the nuance that broad personality dimensions miss. And they do it without forcing anyone into a binary category.

The Neuroticism Gap

This deserves its own section because it is the MBTI’s most consequential omission.

Neuroticism — the tendency toward negative emotionality, anxiety, stress reactivity, and emotional instability — is one of the most powerful predictors of human behaviour. It predicts mental health outcomes, relationship satisfaction, job performance, physical health, and longevity. It is the dimension of personality that matters most when the stakes are high.

The MBTI does not measure it.

This means that two people who score as INTJs on the MBTI could be radically different in their emotional stability. One could be calm under pressure, resilient in the face of setbacks, and emotionally steady. The other could be anxious, reactive, and prone to emotional spirals. The MBTI treats them as identical. The Big Five distinguishes them clearly.

STAR includes Neuroticism through the OCEAN layer. This allows the framework to account for how emotional sensitivity shapes the expression of the other types. A high-Neuroticism Thinker and a low-Neuroticism Thinker are both Thinkers — but they process stress, uncertainty, and social threat very differently. The archetype descriptions account for this variation. The MBTI cannot.

What This Means for Practitioners

If you are using the MBTI in your organisation, your team, or your coaching practice, this study should give you pause.

The MBTI is not measuring what you think it is measuring. Its dimensions do not map cleanly onto the Big Five. Its categories lose data. It misses an entire dimension of personality. And its reliability is lower than the alternatives.

This does not mean the MBTI is useless. It is a conversation starter. It gives people a language for talking about differences. It is accessible and non-threatening. These are real advantages.

But if you are making decisions — about hiring, about team composition, about leadership development, about consumer segmentation — you need a tool that measures what it claims to measure. The Big Five does that. The MBTI does not.

STAR was built on the Big Five because the evidence says it is the right foundation. This study, with nearly 10,000 working adults, is one more data point in a very long line of evidence. The MBTI is popular. The Big Five is valid. When you have to choose, choose validity.

The Bottom Line

The most popular personality test in the world is not the most accurate. That is not a controversial statement. It is an empirical fact. And the framework we built reflects that fact.

David Chadderton is the creator of the STAR Framework and the author of The STAR Framework: Rewriting the Rules of Consumer Engagement (NYC Big Book Award 2025), The STAR Operating System, and Dear Algorithm, It’s Not Me, It’s You. He writes about human behaviour, AI, and the psychology of decision-making on The Unoptimised Human.

References

The STAR Framework

If you enjoyed this essay, you'll find the full argument — and the framework behind it — in the book.