Type Tests, the Big Five and the Barnum Effect: Why You Recognize Yourself in Every Profile

Type Tests, the Big Five and the Barnum Effect: Why You Recognize Yourself in Every Profile

Most people who get into assessment start with a type test. Four letters or a colored quadrant, a label you can remember. You read the result and think: that is me. This feeling explains why type-based instruments rank first in large German companies. It says nothing about their predictive power.

Reading time: about 4 minutes

Four findings

MBTI and persolog lead the ranking. In the 580 largest German companies, two type-based instruments take the first two places.

About 5 percent use cognitive ability tests. The instrument with high predictive power is the rarest one in practice.

35 percent receive a different type. Four weeks later the result comes out differently.

Types are the exception. Only 2 of 129 tools in the PEATS database sort people into types.

Types are the oldest way of ordering personality

Sorting people into types is the oldest system of describing personality. It starts with Hippocrates and the four temperaments, runs through C. G. Jung and arrives at William Marston and the DISC model. Types emphasize similarities, meaning what people in the same group have in common. That makes them easy to grasp and easy to explain in five minutes. Two people with the same four-letter code count as similar in the model, even though their scores on every single scale can be far apart.

The most common instruments are the scientifically weakest

Rüdiger Hossiep, Jonas Schecke and Sabine Weiß surveyed the 580 largest German companies in 2015 (Psychologische Rundschau 66(2), 127 to 129). 120 companies responded, 80 of them use personality questionnaires. The first two places in the ranking are held by two type-based instruments, the Myers-Briggs Type Indicator and the persolog Personality Profile. The German personality questionnaire BIP follows only in third place.

The follow-up survey by Hossiep, Weiss, Netzer and Hossiep ran from May to October 2021 in Germany, Austria and Switzerland. Of 820 large companies, banks and insurers contacted, 115 responded, together employing around 3.2 million people. 75 percent of them use personality questionnaires, 71 percent in Germany, 79 percent in Austria and 93 percent in Switzerland. Here the BIP leads, with 18 companies using it for selection and 32 for development. DISG and persolog reach 6 and 26, Insights MDI 7 and 17.

Cognitive ability tests are the exception

Janina Diekmann and Cornelius König surveyed 166 German companies about their selection methods (2015, in Nikolaou and Oostrom, Employee Recruitment, Selection, and Assessment). Around 98 percent use the interview. Work samples come in at around 37 percent and assessment centers at around 35 percent. Personality tests are used by 15.1 percent, tests of cognitive ability by around 5 percent.

The two surveys paint a different picture. In Diekmann and König, the MBTI and the NEO do not appear among the tests used at all, while in Hossiep the MBTI and persolog sit at the top. The difference comes from the sample. Hossiep surveys the largest companies in the country, Diekmann and König a broader selection. Type-based instruments are therefore mainly a corporate phenomenon.

Sackett, Zhang, Berry and Lievens recalculated the predictive power of the common methods in 2022 (Journal of Applied Psychology 107, 2040 to 2068). The structured interview reaches .42, job knowledge tests .40, work samples .33 and tests of cognitive ability .31. The methods with the highest predictive power are the rarest ones in practice.

Jung's typology has no empirical support

Robert McCrae and Paul Costa examined in 1989 whether the MBTI measures what Jung's theory claims (Journal of Personality 57, 17 to 40). 267 men and 201 women rated themselves on the NEO-PI and were additionally rated by people who knew them. The data do not support the assumption of genuine dichotomies and qualitatively distinct types. The four indices capture aspects of four of the five major personality dimensions. On this finding, Jung's theory is either wrong or not adequately translated into a test.

David Pittenger summarized the evidence in 2005 (Consulting Psychology Journal 57(3), 210 to 221). If types exist, the distributions of the scores would have to show two peaks. They show one. Then there is the stability of the results. After four weeks, 35 percent of participants received a different four-letter type, and after five weeks half of them came out differently on at least one of the four scales. Evidence that such instruments explain anything beyond established methods is missing.

The Big Five emphasize the differences

The Big Five model works with traits. Every person sits somewhere on a scale on every dimension, and that is where the differences between people become visible. The dimensions are supported by factor analysis, and the model counts as the best established one scientifically. Newer instruments look more closely at observable behavior and at job-relevant traits. More on this in Personality vs. Performance Assessments: What’s the Difference – and When Does Each Fit?

Why simple instruments are so popular in HR

Type tests are simple, the results are easy to remember, and participants recognize themselves. That creates acceptance. On top of that, behavior can be learned and can be shown against your own inclination. This limits what a personality test can predict about later performance.

The Barnum effect

Martin Kersting described it in Personalmagazin 9/2015 under the title „Das beschreibt mich und andere“. Statements that are true of almost anyone feel personal. A report full of sentences that fit nearly everyone feels like a hit. A little Barnum creates trust, too much of it lowers the informative value of the test. The instruments with little Barnum are the ones most closely aligned with current scientific findings.

What the PEATS database shows

Type tests are part of the market, and in our database they are the exception. Of 129 active tools, only 2 sort people into types, the MBTI (Myers-Briggs Type Indicator) from The Myers-Briggs Company and CORE™ Potential from Human Edge with its archetypes. All the others work with scales, dimensions or scores. The reason is usually the missing scientific evidence for their predictive power. The full analysis of the market is in The Big Collection of Online Assessment Tools: What They Have in Common and What Sets Them Apart.

Conclusion

A type test is a usable entry point to the topic, because in ten minutes it shows you that personality can be described. For a hiring decision you need an instrument that maps differences and whose predictive power is documented. Anyone who still selects with a type test should know that a third of participants get a different type four weeks later. A result that changes without any reason behind it describes no job-relevant trait. It works for a conversation about yourself and it carries no selection decision.

Relevant Use Cases

T3: Cultural Fit in Teams

T4: Team Development and Teambuilding

Which online assessment tools come into question for these cases, and how they differ, is covered in the PEATS Guides.

Data basis: PEATS database, 129 active tools from 47 providers, as of November 9, 2026.