The DISC test is one of the most widely used personality assessments, but it shouldn’t be used for making hiring decisions. Why? Simply put, it’s not predictive of job performance.
DISC assessments are based on the DISC theory of personality developed by psychologist William Marston in the 1920s. Most DISC tests measure personality along with four traits that make up the DISC acronym: Dominance, Influence, Steadiness, and Conscientiousness.
The DISC sorts people into categories based on self-reported answers. For instance, the DISC might categorize you as a blend of the D and I traits, which are then used to describe your behavioral tendencies. The DISC does have a lot of value as a tool for improving self-knowledge and facilitating teamwork within an organization. However, when it comes to pre-employment testing, the DISC’s use of discrete trait categories is one of its main weaknesses.
Like the Myers-Briggs Type Indicator (which you should also never use for making hiring decisions ), the DISC classifies people into types of buckets instead of describing traits across a spectrum. This goes against trends in modern psychology – recent research tends to support a “trait over type” approach to personality, which views personality traits as continuums rather than as binary absolutes.
So for instance, a type-based test might categorize you as a Conscientious type, while a trait spectrum test might determine that you are 74th percentile in conscientiousness. There’s a big difference in specificity between these two outcomes and, as a result, tests that attempt to categorize 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 are able to compare one person’s scores with the scores of others in a larger population. That’s how normative personality tests are able to provide you with percentile scores – scoring 81st percentile in extroversion means you are more extroverted than 81% of the people in the norming group. And for many normative personality tests, these sample populations are often massive, and as a result, more reliable.
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. Normative personality tests, such as the EPP, use percentiles to find correlations between personality traits and job performance. For instance, a consistent correlation has been found between high competitiveness (i.e. people with higher percentiles in the Competitiveness trait) and job success in a sales role. This information can then be used by employers to make an informed hiring decision – when a job candidate takes a normative personality test, the employer can see how the candidate’s competitiveness percentile compares with those who typically excel in a sales role.
DISC assessments lack this predictive ability, and that’s the main reason why they aren’t recommended for pre-employment testing. One of the leading publishers of the DISC even 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.”
So while many organizations may find value in this personality test as a tool for improving self-awareness and fostering team communication, this assessment should NOT be used for making hiring decisions.