JTI is a Jungian type instrument developed in Norway, independently certified against the European standard for psychological tests, and built for the development of people, teams and leaders. This page sets out the evidence: what has been measured, how, and what it means in practice.
Carl Jung set out his theory of psychological type in Psychological Types (1921): two attitudes, extraversion and introversion, and four functions — two ways of perceiving, sensing and intuition, and two ways of judging, thinking and feeling. JTI adds a fourth dichotomy, judging–perceiving, which describes how a person prefers to deal with the outer world.
JTI was developed in Norway by the organisational psychologists Thor Ødegård and Hallvard E. Ringstad, and has been in professional use since the early 2000s. The aim throughout has been to stay close to Jung's own definitions. This shows most clearly in Thinking–Feeling: in JTI both are rational ways of reaching a decision — one analytic, one based on values — rather than a contrast between tough and tender.
Reliability asks two questions. Does a person get the same result when they take JTI again? And do the items within each scale measure the same thing?
240 adults in Norway took the online JTI twice, on average 9.5 months apart (from about one month up to two years). The analysis was carried out by Dr Iselin Reknes, University of Bergen, commissioned by Optimas, and formed part of the evidence DNV assessed in 2025.
| Measure | E–I | S–N | T–F | J–P |
|---|---|---|---|---|
| Correlation, all respondents (N = 240) | .86 | .83 | .79 | .80 |
| Correlation, retested after more than six months (n = 148) | .87 | .83 | .82 | .82 |
| Same preference on retest | 90 % | 91 % | 93 % | 91 % |
71 %
95 %
71 % got exactly the same four-letter type on retest, and 95 % matched on at least three of the four letters.
Source: Reknes, reliability analyses, 2025. Type agreement computed from the study's type-by-type table.
Across about 440,000 completed JTIs in all language versions, Cronbach's alpha is .80 to .84 for each scale.
| Measure | E–I | S–N | T–F | J–P |
|---|---|---|---|---|
| Cronbach's alpha (about 440,000 respondents) | .84 | .80 | .81 | .82 |
Source: OnlineJTI database analysis, 2026, all language versions.
Validity asks whether JTI measures what it sets out to measure. The evidence comes from the structure of the scales, from comparisons with established questionnaires, and from how preferences differ across occupations.
In an early study, the JTI scales correlated with the Big Five where theory says they should: extraverts scored higher on Extraversion, people preferring Intuition higher on Openness, and people preferring Judging higher on Conscientiousness.
Early study, NTNU, 2002 · N = 57 employed adults
77–84 %
In an early comparison, JTI and the MBTI placed people on the same side of each preference 77–84 % of the time. Correlations between matching scales were .72 (E–I), .82 (S–N), .81 (J–P) and .49 (T–F). The lower T–F figure reflects JTI's Jungian definition of Thinking and Feeling, which differs from the MBTI's.
Early study, around 2002 · N = 81
In our 2026 analysis of the full database, each of the four scales behaves as a single factor: the items in a scale reflect one underlying preference.
Own analysis, 2026 · about 440,000 respondents
The comparisons with the Big Five and the MBTI come from the instrument's early validation studies and are labelled with their year and sample size.
In a study of 41,522 respondents, people's preferences differed across occupations and vocational interests in the ways type theory predicts (all associations p < .001). Thinking–Feeling showed the strongest link (Cramér's V = .19 across RIASEC interests, .20 across industries): Thinking preferences were most common in Realistic and technical work, Feeling preferences in education, social and creative work. Sensing was over-represented in Realistic occupations and Intuition in artistic, creative and media work; Extraversion in Enterprising roles, business, finance, retail and sales, and Introversion in technology, engineering and Realistic work.
At the level of whole types, ISTJ was over-represented in Realistic work and in technology and engineering, INFP in artistic, creative and media work, INTP among people with Investigative interests, and ISFJ in education and research. Judging–Perceiving showed the weakest link (V ≈ .06–.08). Across the sixteen types and six RIASEC interest areas, χ²(75) = 2,398, V = .11.
RIASEC interest areas and industries. The dashed line marks the share across all respondents (61 %).
Occupation study, 2025, N = 41,522, Optimas database; re-analysed October 2026. Patterns are adjusted standardised residuals.
The effect sizes are small to moderate, as is typical for links between personality and occupation. This is evidence that JTI measures real differences between people; it does not mean that a type is suited or unsuited to any job, and JTI is not used to choose careers.
The EFPA Test Review Model was developed by the European Federation of Psychologists' Associations to evaluate psychological tests on their theoretical basis, documentation, materials, norms, reliability and validity. DNV certifies tests against this model; the assessment is carried out by two independent reviewers, who examine the documentation and the research behind it.
First certification
Full review against the EFPA model of the JTI documentation, materials, norms, reliability and validity. Certified for development use, not for selection.
Recertification
Documentation review; certificate renewed for three years. For the next review, the reviewers asked for a longer-interval retest study and criterion-related evidence.
New studies
At DNV's request, a 240-person retest study with an average interval of 9.5 months and an occupation study of over 40,000 respondents.
Recertification
Approved for personal development purposes. The current certificate is valid until 28 September 2028.
JTI is certified for work and occupational use and approved for personal development; it is used for personal, team and leadership development in work settings. It is not designed or certified for recruitment, selection or ranking people, and we do not claim that it predicts job performance.
A JTI result is a starting point for a conversation. In feedback, the respondent compares the description with their own experience and decides which type fits best.
JTI is administered and fed back by practitioners trained and certified through our distributors.
About certificationAhead of the next review in 2028, our research programme focuses on two areas.
Studies linking JTI results to measurable outcomes in development work, such as training effectiveness and team performance.
Data from a wider range of industries and regions, so that reference data reflect the full breadth of people who use JTI.
We will add new results to this page as they are completed.
The certificate and the research reports are available on request.
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