The short answer
Insight Metrics uses the 16-type framework that goes back to Carl Jung’s Psychological Types (1921) and the Myers-Briggs model built on it. Four scales, E/I, S/N, T/F and J/P, give 16 types; every letter is reported with a strength; and a type describes preferences, never ability, health or worth. The extra -A and -T letters are not part of it.
On this page
DefinitionWhat Is the Insight Metrics Personality Framework?
In shortOur framework describes personality as 16 types built from four pairs of preferences. It follows Carl Jung’s theory of psychological types and the Myers-Briggs model built on it, and it reports every letter with a strength, as a starting point for self-understanding rather than a label.
A personality framework is the set of ideas a test and its reports are built on: what is measured, how results are described and where the limits are. Ours is the type framework most people know from the Myers-Briggs Type Indicator (MBTI): four scales, two letters on each, and 16 personality types from their combinations. Every page on this site, from the type guides to the compatibility chart, uses the same definitions set out here.
Five rules our framework follows
- Preferences, not abilities. A type describes what comes naturally to you, not what you can or cannot do.
- Every letter has a strength. 52% and 90% are both “Introvert”, but they are not the same result.
- Four letters, eight functions, four groups. The letters are the summary; functions and groups explain how the parts work together.
- A type is a likely fit, not a verdict. One sitting is an indication. You decide whether the description fits you.
- Sources and limits on the page. Where research disagrees with type theory, we say so in the same section.
The four scalesThe Four Preference Scales Behind the 16 Types
In shortThe four scales are Extraversion or Introversion (E/I), Sensing or Intuition (S/N), Thinking or Feeling (T/F) and Judging or Perceiving (J/P). Your type is your side of each one, for example INFJ or ESTP.
Each scale asks one question about how you prefer to work. The table gives the question, what each side means and one real statement from our free test for each side, so you can see how the scale is measured. The last column shows how common each letter was in the US national sample used for the MBTI Manual.
| Scale | The question | First letter | Second letter | Share of people |
|---|---|---|---|---|
| E / I | Where do you get your energy? | E Extraversion: From people, activity and talking things through “I feel energized after spending time with a group of people.” | I Introversion: From quiet, reflection and thinking things through first “I need time alone after social events to recharge my energy.” | 49.3% · 50.7% |
| S / N | What kind of information do you trust first? | S Sensing: Facts, details and what has been tried “I trust concrete facts and data more than gut feelings.” | N Intuition: Patterns, meanings and what could be “I naturally see patterns and connections that others tend to miss.” | 73.2% · 26.8% |
| T / F | How do you make decisions? | T Thinking: By logic, consistency and fairness rules “I make decisions based on logic rather than personal feelings.” | F Feeling: By values, empathy and the effect on people “I consider people's feelings carefully before giving feedback.” | 40.3% · 59.7% |
| J / P | How do you handle plans and the outside world? | J Judging: With plans, closure and decisions made early “I like to plan things in advance rather than leave them open.” | P Perceiving: With options left open and plans adapted as you go “I work best when I can be flexible and spontaneous.” | 54.1% · 45.9% |
Two letters are easy to misread. Judging does not mean judgemental: it means preferring decisions and closure. Perceiving does not mean perceptive: it means preferring to keep options open. In the same way, Feeling types think, and Thinking types feel; the scale is about which one leads when you decide.
Two letters from four scales give 2 × 2 × 2 × 2 = 16 combinations, which is why there are exactly 16 personality types. For what each combination is like, see the 16 type guides; for how common each one is, see the rarest personality types.
StrengthPreferences, Not Boxes: How Strong Is Each Letter?
In shortEach letter comes with a strength from 50% (an even split) upward. A strong preference shows up in most situations; a letter near 50% means you use both sides and a retake may flip it.
Type theory says you prefer one side of each scale, the way most people prefer one hand. It does not say you never use the other side. That is why our results show a percentage for each letter rather than the letter alone.
Read the strength like this: above about 75%, the letter is clear and usually stable; between 60% and 75% it is a real but moderate preference; under 60% it is slight, and you may relate to parts of two types. If one of your letters is borderline, read both type guides, for example INFJ and INFP, and keep the one that describes you better.
The example bars above are an illustration, not a real result. Our guide to how our tests work shows exactly how the percentages are calculated.
Get Your Four Letters and How Strong Each Is
The free personality test reports every letter with its strength, so you can see which preferences are clear and which are borderline. Free to take · Free summary · Full report optional.
Type dynamicsThe Eight Cognitive Functions and Type Dynamics
In shortJung described eight cognitive functions: Sensing, Intuition, Thinking and Feeling, each turned outward (extraverted) or inward (introverted). Every type uses all eight, but in a fixed order of preference called its function stack, such as Ni, Fe, Ti, Se for INFJ.
The four letters are a summary. Type dynamics is the older idea underneath them: that your type is an order of mental processes, led by one dominant function and supported by an auxiliary one. The J or P letter tells you which of your two middle letters you show to the outside world, and the E or I letter tells you whether the dominant one faces outward or inward.
- NiIntroverted Intuitionbuilds one deep, long-range picture from patterns
- NeExtraverted Intuitionjumps between possibilities and connections
- SiIntroverted Sensingcompares the present with tested past experience
- SeExtraverted Sensingtakes in the live, physical moment
- TiIntroverted Thinkingchecks ideas for inner logical consistency
- TeExtraverted Thinkingorganises facts, steps and results in the outside world
- FiIntroverted Feelingweighs choices against personal values
- FeExtraverted Feelingreads and tunes in to the needs of the group
| Type | Dominant | Auxiliary | Tertiary | Inferior |
|---|---|---|---|---|
| INTJ | Ni | Te | Fi | Se |
| INTP | Ti | Ne | Si | Fe |
| ENTJ | Te | Ni | Se | Fi |
| ENTP | Ne | Ti | Fe | Si |
| INFJ | Ni | Fe | Ti | Se |
| INFP | Fi | Ne | Si | Te |
| ENFJ | Fe | Ni | Se | Ti |
| ENFP | Ne | Fi | Te | Si |
| ISTJ | Si | Te | Fi | Ne |
| ISFJ | Si | Fe | Ti | Ne |
| ESTJ | Te | Si | Ne | Fi |
| ESFJ | Fe | Si | Ne | Ti |
| ISTP | Ti | Se | Ni | Fe |
| ISFP | Fi | Se | Ni | Te |
| ESTP | Se | Ti | Fe | Ni |
| ESFP | Se | Fi | Te | Ni |
Function stacks are a theory, not something any short questionnaire measures directly. If you want to see how you lean on each of the eight functions, take our cognitive functions test; each type guide also explains its own stack in plain language.
Type groupsThe Four Type Groups: Analysts, Diplomats, Sentinels, Explorers
In shortThe 16 types fall into four groups of four. Intuitive types are grouped by their T or F letter (NT Analysts, NF Diplomats); sensing types by their J or P letter (SJ Sentinels, SP Explorers).
Why not group everyone the same way? Because type theorists found that the second letter changes what matters most. For intuitive people, the deciding letter (T or F) shapes their goals; for sensing people, the way they deal with the outside world (J or P) does. The same four-way split appears in David Keirsey’s temperaments, where the groups are called Rationals, Idealists, Guardians and Artisans.
Group shares: US national sample, MBTI Manual (3rd ed., 1998). The group names are the ones used across this site, including the menu and the compatibility chart.
-A and -TWhat Do -A and -T Mean in a Personality Type?
In short-A (Assertive) and -T (Turbulent) are a fifth letter added by one popular free test, 16Personalities, to show how self-assured or stress-prone someone is. They are not part of the original Myers-Briggs types, and our 16-type test does not score them.
A result like INFJ-T or ENTP-A comes from an extra “Identity” scale. It is close to what personality research calls emotional stability, the opposite end of the Big Five trait Neuroticism: Turbulent types worry and self-criticise more, Assertive types recover from setbacks faster. That trait is real and well researched, but it sits outside type theory, which describes preferences rather than how much stress you feel.
So we keep it separate. Our 16-type result shows four letters and the strength of each. If you want to measure emotional stability properly, our Big Five personality test reports Neuroticism and its six facets against a large norm group. Each type guide also explains its -A and -T versions, for example INFJ-A vs INFJ-T, and our article on high neuroticism explains the trait behind the T.
HistoryWhere the 16 Personality Types Come From
In shortThe 16 types come from Carl Jung’s 1921 book Psychological Types, which Katharine Cook Briggs and Isabel Briggs Myers turned into a questionnaire in the 1940s. The Myers-Briggs Type Indicator was first published with a manual in 1962.
- 1921Carl Jung publishes Psychological Types in German (English, 1923): the attitudes Extraversion and Introversion and the four functions.
- 1920s–1940sKatharine Cook Briggs and her daughter Isabel Briggs Myers study Jung, then begin writing a questionnaire during the Second World War, adding a fourth scale, Judging or Perceiving, to Jung’s three.
- 1962Educational Testing Service publishes the Myers-Briggs Type Indicator with its first manual.
- 1978David Keirsey and Marilyn Bates publish Please Understand Me, grouping the 16 types into four temperaments.
- 1980Isabel Briggs Myers’ book Gifts Differing appears, the classic description of the 16 types.
- 1989Robert McCrae and Paul Costa compare the MBTI with the Big Five and find that four of the five traits line up with the four scales.
- 1998The MBTI Manual, 3rd edition, publishes the US national sample whose type shares our type guides quote.
MBTI and Myers-Briggs are trademarks of The Myers-Briggs Company. Insight Metrics is not affiliated with it; our tests are our own and use the widely known 16-type model.
Type and traitsHow the 16 Types Relate to the Big Five
In shortAll four type scales line up with one of the Big Five traits each: E/I with Extraversion, S/N with Openness, T/F with Agreeableness and J/P with Conscientiousness. The Big Five trait Neuroticism has no type scale.
The Big Five is the trait model most personality researchers use. When McCrae and Costa gave both questionnaires to the same adults in 1989, the type scales correlated with four of the five traits. That matters for how you read a result: a type describes the same personality differences as the traits, but sorts them into two boxes per scale where the Big Five keeps a continuous score.
| Type scale | Big Five trait | Link found | What it means |
|---|---|---|---|
| E / I | Extraversion | strong (about 0.7) | the same idea under the same name |
| S / N | Openness to experience | strong (about 0.7) | Intuitive types score higher on Openness |
| T / F | Agreeableness | moderate (about 0.45) | Feeling types score higher on Agreeableness |
| J / P | Conscientiousness | moderate (about 0.5) | Judging types score higher on Conscientiousness |
| — | Neuroticism | no matching scale | the gap that -A / -T tries to fill |
Link sizes are correlations reported by McCrae and Costa (1989), rounded; 1.0 would be a perfect match. If you want trait scores rather than a type, take our Big Five test.
LimitsWhat a Personality Type Can’t Tell You
In shortA personality type cannot tell you how intelligent, talented, healthy or successful you are, and it should not be used to hire people. It also shifts for many people on a retake, mostly on letters near 50%.
- Not a diagnosis. A type says nothing about mental health. If something is weighing on you, talk to a qualified professional, not a test.
- Not ability. No type is smarter, more creative or more capable than another. Preferences are not skills.
- Not a hiring tool. Even the publisher of the official MBTI says it should not be used to select job candidates. We agree.
- Not fixed to the decimal. Studies of the official questionnaire found that between a quarter and a half of people get at least one different letter when they retake it a few weeks later, mostly on scales where they scored near the middle.
- Boxes versus scales. Most people are not clearly one side or the other on every scale. Trait research finds scores pile up near the middle, not in two separate camps, which is why we always show the strength.
What the research says
Reviews of the MBTI find good evidence that its scales measure real personality differences (they match the Big Five traits above), and weaker evidence for the claim that people fall into 16 distinct types. Type is most useful as a shared language for differences, which is how we use it.
Pittenger (2005); McCrae & Costa (1989)
Our rulesHow We Apply the Framework on This Site
In shortEvery Insight Metrics page uses the same definitions, quotes one named sample for type shares, calls a famous person’s type a likely type, and is written and reviewed by a named editor.
- One set of definitions. The scales, functions and groups on this page are the ones used in all 16 type guides, the type comparisons and the careers by type guides.
- One sample for numbers. Type shares come from the US national sample in the MBTI Manual (1998), with the sample named next to the figure.
- Likely types only. On famous people pages, a type is always a likely, unofficial typing, and we do not type living politicians.
- Compatibility is theory. Our compatibility chart describes type theory, not a prediction about any couple.
- Named people. Each page names who wrote it and who reviewed it; see the editorial team.
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QuestionsFAQ
What framework does Insight Metrics use?
We use the 16-type framework that goes back to Carl Jung’s Psychological Types (1921) and the Myers-Briggs model: four preference scales (E/I, S/N, T/F, J/P), each reported with a strength, eight cognitive functions and four type groups.
Is the Insight Metrics test the official MBTI?
No. MBTI and Myers-Briggs are trademarks of The Myers-Briggs Company and we are not affiliated with it. Our test is our own and uses the widely known 16-type model.
What do the four letters of a personality type mean?
Each letter is your side of one scale: E or I (where you get energy), S or N (what information you trust first), T or F (how you decide) and J or P (how you handle plans).
How many personality types are there?
There are 16 personality types: two options on each of four scales gives 2 × 2 × 2 × 2 = 16 combinations.
What are the four personality type groups?
Analysts (NT: INTJ, INTP, ENTJ, ENTP), Diplomats (NF: INFJ, INFP, ENFJ, ENFP), Sentinels (SJ: ISTJ, ISFJ, ESTJ, ESFJ) and Explorers (SP: ISTP, ISFP, ESTP, ESFP).
What do -A and -T mean?
-A means Assertive and -T means Turbulent. They come from an extra Identity scale used by 16Personalities, close to the Big Five trait Neuroticism, and are not part of the original Myers-Briggs types.
Does your test give -A or -T?
No. Our 16-type test reports your four letters and the strength of each. To measure emotional stability, take our Big Five test, which scores Neuroticism and its facets.
What are cognitive functions?
Cognitive functions are the eight mental processes in Jung’s theory: Sensing, Intuition, Thinking and Feeling, each extraverted or introverted. Each type uses them in a fixed order called its function stack.
Is personality type theory scientific?
Partly. The four scales match well-researched Big Five traits, but the idea that people fall into 16 separate types has weaker support. Type works best as a shared language for real differences.
Can your personality type change?
Your core preferences tend to be fairly stable, but a letter you score near 50% on can change between sittings, and how you use your preferences grows with age and experience.
SourcesSources
- Jung, C. G. (1921/1923). Psychological Types (H. G. Baynes, Trans.). London: Kegan Paul.
- Myers, I. B., with Myers, P. B. (1980). Gifts Differing: Understanding Personality Type. Palo Alto, CA: Davies-Black.
- Myers, I. B., McCaulley, M. H., Quenk, N. L., & Hammer, A. L. (1998). MBTI Manual (3rd ed.). Palo Alto, CA: Consulting Psychologists Press.
- Keirsey, D., & Bates, M. (1978). Please Understand Me: Character and Temperament Types. Del Mar, CA: Prometheus Nemesis.
- McCrae, R. R., & Costa, P. T. (1989). Reinterpreting the Myers-Briggs Type Indicator from the perspective of the five-factor model of personality. Journal of Personality, 57(1), 17–40.
- Pittenger, D. J. (2005). Cautionary comments regarding the Myers-Briggs Type Indicator. Consulting Psychology Journal: Practice and Research, 57(3), 210–221.
