Why You Should Never Use Myers-Briggs or the DISC for Recruitment

The Myers-Briggs Type Indicator (MBTI) and DISC assessment have been widely used in corporate settings for decades. Many job candidates mention these tests when discussing their past experiences. However, despite their popularity, these assessments have significant shortcomings and should never be used to make recruitment decisions for the following reasons:

They Are based on Outdated Science: Types vs Trait Based Approach

The MBTI was originally developed during WW2 and is based on Carl Jung’s typological theory of personality, while the DISC assessment was developed in the 1920s and is based on the DISC theory of personality developed by psychologist William Marston in the 1920s.

The MBTI and DISC divide certain elements of human personality into binary categories, or types. The problem with this old approach is that contemporary psychological research clearly shows that human personality cannot be accurately divided into discrete types, and tests that use this model tend to lack both reliability and validity.

The study of personality has come a long way since the MBTI and DISC were developed and the recent research tends to support a “trait over type” approach to personality and views personality traits like introversion/extraversion as dimensions or continuums rather than as binary absolutes. The concept of personality "traits" measured on a continuum is now widely accepted and has superseded the older personality "types" model that originated with Jung.

As an example, a type-based test might categorise you as a conscientious type, while a trait spectrum test might determine that you are in the 74^th percentile. There’s a big difference in specificity between these two outcomes and, as a result, tests that attempt to categorise people into types tend to lack both reliability and validity when compared to percentile tests.

Another downside to using the DISC in the hiring process is that it is not a normative assessment. Normative tests can compare one person’s scores with the scores of others in a larger population. That’s how normative personality tests can provide you with percentile scores – scoring in the 74^th percentile in extroversion means you are more extroverted than 74% of the people in the normative or reference group. The ability to compare one individual's personality to others is the critical missing piece needed to validate a personality test's ability to predict anything at all.

MBTI and DISC Lack Reliability

A study on the MBTI demonstrated that when a sample group took the MBTI and then took the test again 5 weeks later, about 50% of people received different results. Because the test separates people into types, a person who does not have a strong inclination for one type over the other may be just a few questions away from being placed into an entirely separate category. This demonstrates that the test has poor test-retest reliability.

MBTI and DISC Do Not Predict Job Performance

Studies have consistently demonstrated that the tests fail to predict job performance in any meaningful way. If the main reason to use a pre-employment test is to predict job performance, then a test that lacks this predictive validity is essentially useless as an employee selection device.

MBTI and DISC Publishers Discourage Their Use in Hiring

The Myers & Briggs Foundation very clearly state that “it is not ethical to use the MBTI instrument for hiring or for deciding job assignments.” This is because the test is not predictive of job performance.

One of the leading publishers of the DISC states on their website that the “DISC is not recommended for pre-employment screening because it does not measure a specific skill, aptitude or factor specific to any position” and that the “DISC is not a predictive assessment so assumptions should not be made regarding an applicant's probability of success based solely on their style.”

Apparently, the MBTI and DISC are useful for team building, although I am aware of a few better ways to improve a team’s performance. If an organisation wants to do a team building exercise using a personality profile I would recommend using the NEO-PI-3, which is the five-factor model and has significantly better validity and reliability than the MBTI and DISC. Why use something that is old, outdated and invalid when there are contemporary and statistically sound profiles on the market. It’s ironic that many organisations talk about innovation yet use old and outdated profiles.

Better Alternatives Exist

If you are looking for an effective and scientifically valid personality test for hiring, consider trait-based assessments that provide percentile scores and compare candidates to a normative sample.

Some reliable options include:

• Big Five Personality Assessments (e.g., NEO-PI-3)
• Employee Personality Profile (EPP)
• Hogan Personality Inventory (HPI)

These tests offer greater reliability, validity, and predictive power, making them far superior choices for hiring.

Personality tests are valuable tools to help find the best talent in your applicant pool, and using tests that produces meaningful, predictive results in the hiring process is the key to getting the most out of testing. For recruitment, I would recommend using the Employee Personality Profile from Criteria. An excellent profile with good reliability, validity and job prediction utility.  

Fermion specialises in psychometric testing for recruitment. Please contact Fermion to discuss how a test of IQ, EQ and a personality profile, or any other psychometric test, can help with you your recruitment decisions.