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Can you really trust personality tests?

Updated: 6 days ago

Personality tests are extremely popular tools to help you explore your individual traits, facilitate self-awareness, enhance your personal and professional development, and even serve as a means for entertainment and social interaction. 

But how accurate are they, really?

Recently, we ran studies aimed at measuring the predictive accuracy of the most popular personality test frameworks (MBTI-style/Jungian, Big Five, and Enneagram) for predicting life outcomes, and then created a single, efficient test that could measure all of these simultaneously - we call it the Ultimate Personality Test. We were also excited to release this research in Scientific American last week!

In today's article, we want to lay out some key takeaways we learned from these studies, for you to consider when doing personality tests. If you are interested in the details of how we designed and conducted the study, you can read our detailed report by clicking here

The broad strokes of our method are as follows: We measured the personalities of over 500 people in the U.S. using all three of the most popular personality systems, and then used each system to try to predict 37 "life outcomes" of those people. We measured how accurate the predictions were in each case. These life outcomes included things like:

  • how many close friends a person has, 

  • how satisfied each person says they are with their life, 

  • and whether they receive promotions at work, 

among many other things.

Here are some of the most interesting findings:

Key takeaways from our study 

  • Big Five Superiority: The Big Five personality test framework outperformed the other two frameworks that we tested - Jungian (MBTI-inspired) and Enneagram in predicting life outcomes.

accuracy of personality tests

  • Neuroticism's Impact: Removing Neuroticism from the Big Five resulted in a substantial drop in predictive accuracy.

  • Continuous vs. Binary: Continuous scores in the Jungian (MBTI-style) framework predicted outcomes substantially better than binary categories (which is important since MBTI-style tests are usually presented in a categorical form)

accuracy of personality tests
  • Trait Distribution: Most personality traits approximately formed bell curves, meaning that most people fall near the middle on each trait, suggesting binary categorization (as is typical with MBTI-style tests) might introduce substantial noise.

accuracy of personality tests
  • Jungian (MBTI-style) Limitations: The Jungian 4-letter framework showed less predictive accuracy than the Big Five, mostly due to its use of binary types (splitting participants into letters like I vs. E and N vs. S) and its failure to measure Neuroticism. By adapting the Jungian framework to give continuous scores (rather than categories) and excluding Neuroticism from the Big Five, then the predictive gap between the two frameworks narrows. However, even with these adjustments, the Big Five (without Neuroticism) still slightly outperformed the modified Jungian test (with continuous scores, not binary types).

  • Cross-framework Relations: Almost every Jungian trait correlated with a specific Big Five trait: the Jungian Extraversion/Introversion aligned with Big Five’s Extraversion, Intuition/Sensing with Openness, and Feeling/Thinking with Agreeableness. However, the Judging/Perceiving trait was associated with three of the Big Five traits.

  • Integration Ineffectiveness: Combining the Big Five and Jungian test results didn't improve prediction accuracy over using just the Big Five alone. This suggests that the Jungian test does not add significant predictive value beyond what is already captured by the Big Five.

  • Enneagram's Surprisingly Good Performance: Despite its simplicity, the Enneagram binary (using only the 1-digit Enneagram variable - e.g., Type 9) performed better than the binary Jungian Type at predicting life outcomes. However, the Enneagram still underperformed the Big Five.

  • Participant Perception: Despite the Jungian test’s lower predictive accuracy, participants felt better after reading their Jungian assessments than their Big Five assessment, likely due to the Jungian test's positive framing — it feels better to be called “Thinking” than someone “with low Agreeableness”.

In short, our study suggests that if you care about how well a personality test can predict outcomes in your life (or other people's), then the Big Five test is likely superior to a Jungian (MBTI-style) and Enneagram approach. It also suggests that dichotomizing traits into binaries (rather than using continuous scores) substantially reduces predictive accuracy for these tests.

If you have some extra time, you also may find it interesting to read the piece we published in Scientific American,  "Personality Tests Aren’t All the Same. Some Work Better Than Others", and watch Spencer Greenberg's video about our research (the first ever video on Spencer's new YouTube channel!). 

Would you like to see your own personality results using the Big Five, Jungian, and Enneagram frameworks?

1 Comment

David Palmer
David Palmer
Mar 15

Have you examined how people make good use of personality test results?

Personality is such an interesting topic, but I've generally be really skeptical about the utility of taking personality tests. I suspect a high rate of desirability bias or simple self-deception when these are self-administered.

While I think self-knowledge is an important pursuit, and understand the Big-five personality model reliably identifies persistent traits, my intuition is that understanding our personality provides less value than things such as schemas, or domain-specific self-efficacy.

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