Untangling Personality Tests

Personality tests, and personality psychology in general, are topics fraught with disagreement and controversy. In fact, it was only after much deliberation that we decided Retexo should offer personality assessments at all. One thing that helped us get comfortable with that decision was realizing that — as with many issues — much of the difficulty arises when we conflate different ideas without realizing it. When we disentangle these concepts, we ask better questions, and much of the conflict and confusion simply evaporates.

Theory or test?

Consider three well-known names in personality testing, DISC, the “Big Five,” and Myers-Briggs.

• The Big Five, or Five Factor Model (FFM) is a theoretical model of personality. There are tests that measure the Big Five traits, but the FFM is the underlying theory, not a personality test, and thus asking if the Big Five is better than DISC is like asking if length is better than a ruler. They are apples and oranges.
• The Myers-Briggs Type Indicator (MBTI) is a personality test developed by Katharine Cook Briggs and her daughter, Isabel Briggs Myers. Myers and Briggs based their work on the theoretical model of Carl Jung.
• DISC (generically) is also a theoretical model of personality proposed by William Marston in his 1928 book Emotions of Normal People (as if any of us are “normal!”). But when someone tells you they took a DISC assessment, they could be referring to any one of the many assessments that are based on the DISC model, including DiSC® (registered trademark with a lower-case “i”). That is the particular DISC assessment Retexo offers, published by Wiley Education. Wiley’s original DiSC® Classic Paper Profile was the first assessment to measure DISC traits.

There are many theoretical models of personality, including the FFM, DISC, Jungian types, the enneagram, the six-dimensional HEXACO model, Raymond Cattell’s 16 personality factors (16PF), and others. All are good, but imperfect attempts to understand fundamental aspects of human nature.

Likewise, there are even more personality tests designed to measure the personality traits conceived in the various theoretical models. For example, the Revised NEO Personality Inventory (NEO PI-R) and the Big Five Personality Trait Short Questionnaire (BFPTSQ) both measure the Big Five traits. In some cases, the developer of the theory was also involved in the creation of a test, but more often they were not. Marston never created or published a DISC test instrument. The DiSC® assessments offered by Retexo are based on Marston’s core ideas, but after decades of additional research, they bear little resemblance to the original work of the 1920s.

Which one is right?

Assuming we are asking which theory of personality is “right,” then the answer is an academic rabbit-hole in which you will find little consensus. In our view, there is no such thing as a “correct” theory of personality. Personality itself is a concept we humans invented, and as with all human behavior, the patterns of preferences, drives, and styles we call personality are the result of complex interactions of genetics and our environment that are unlikely to ever fit perfectly into any theoretical model.

A better question: Is it useful?

Instead of asking if a personality theory is right, we might be better off asking if it is useful. Neils Bohr’s theoretical model of the atom is not “right.” We now know that atoms do not really look like the Bohr model. Nonetheless, the Bohr model has proven extremely useful and has led to an untold number of scientific advancements. Likewise, we do not consider the DISC model to be right. The Big Five might provide a more nuanced and comprehensive view, but we still find DISC to be extremely useful, especially given the intended application. The question, “is it useful?”, after all, can only be answered in the context of “useful for what?” For academic research, the Big Five or others might be a better choice. But for use in personal development by lay-people, DISC can be quite valuable, easier to interpret, and lends itself much better to practical application.

Which test is most accurate?

Again, we must be more specific. Accuracy is only meaningful relative to the thing we are trying to measure. Any given personality test instrument can only be evaluated against the dimensions it is intended to measure. Even tests designed to measure traits from the same theoretical model may not measure exactly the same dimensions.

When comparing psychometric instruments, it is more appropriate to ask about validity and reliability. Validity asks if the test measures what it is intended to measure, and is often assessed by comparing results to other well-accepted tests that measure the same thing. Reliability asks whether the results are consistent and repeatable, and can be evaluated by comparing results of multiple tests taken over time. There are a variety of accepted statistical measures for both.

Ask instead, is it accurate for me?

No psychometric instrument is perfectly valid or reliable. Wiley’s DiSC assessments are backed by over four decades of research and development, and score well in tests of validity and reliability*. That’s one reason we chose to offer DiSC over other options, but for use as a personal development tool, we would encourage people not to get too hung up on small variations in validity and reliability. The MBTI, for example, is often criticized for lack of statistical robustness and for deviating from Jung’s theory, yet millions of people have found it helpful.

Ultimately that is what matters most. If a person gains new awareness from MBTI that makes their life experience and their relationships better, is that result not real if the test-retest repeatability of the MBTI is below an arbitrary statistical threshold? Conversely if your DISC report has a result you disagree with, you are not required to accept it just because it came from a well-validated test. It is simply an opportunity for reflection. If you give real consideration to that result and still disagree, ignore it and move on. But more often than not, high-quality assessments like DiSC® and others can help us gain valuable insights, and we believe that is what makes them worth doing.

Finally, like most tools, there are good and bad uses for personality tests. Increasing self-awareness and compassion are good uses. Pigeon-holing people and deciding which jobs they can or cannot do are really bad uses. We worry about these things, and that is why we wrote our Personality Test Pledge. Check it out before you use DiSC, or any other assessment.

*Check out the Everything DiSC Research Report if you want all the details.