What Makes A Personality Test Reliable And Valid


Personality tests are fun, but do they actually capture who you are? Organisations and consultants view personality testing with much scrutiny. Unfortunately, due to the era of the ‘which character are you most like?’ testing made famous by the likes of Buzzfeed, the validity and reliability of personality tests are called into question. Commercially oriented personality tests now undergo rigorous validation and reliability testing to prove their accuracy. Now, the most valid personality tests provide remarkable insights into what makes a person tick. So, what makes a personality test reliable and valid?

Are Personality Tests Valid?

Personality tests can be fun and tell you which character you are most like in your favourite tv show or movie. But are these personality tests reliable and valid? The answer is most likely no. These tests are designed to provide entertainment rather than give you actionable insights to help personal and professional development. The gimmicky perception of these tests has seeped into the view of workplace personality tests. A New York Times article even likened personality tests to the “astrology of the office,” The article scrutinises the way organisations use personality tests in the workplace for recruitment, team building, and leadership development. 

So, are personality tests valid? Yes, there are personality tests that provide valid and accurate people analytics that inform talent and HR decisions. However, not all personality test applications have legs to stand on, and we need to be sceptical about what they claim to measure. When choosing a personality test, we strongly recommend evaluating factors, including validation and reliability statistics regarding the assessment. If the provider is unable to provide transparency in this area, remove it from your list. Researching the reliability and validity of your potential test provider will ensure you receive the most accurate and scientifically backed data. 

How Can You Prove The Validity Of Personality Tests Or What Proves The Validity Of Personality Tests 

When people discuss personality tests, they often ask how can you prove the validity of personality tests or what proves the validity of personality tests? Validity is a measure of how well an assessment measures what it claims to measure. For example, a test might claim to measure a personality trait. Instead, it may measure only one dimension of personality or emotions that reflect situational environments. A valid test ensures that the results are an accurate reflection of the dimension undergoing measurement. 

A robust validity study will also include a varied sample set of research participants of different ages, cultures, languages and genders. Providing a broad sample set of data ensures results apply to a vast range of cultures and populations. 

The validity of a personality test is not determined by a single test but by a body of research. The two most common validation methods are construct validity and criterion validity. 

Construct Validity

Construct validity proves that a test measures a construct rather than a skill or ability. Intelligence, motivation and anxiety are all examples of constructs, they exist in the brain, but we cannot directly observe them. For example, you can tell someone is anxious if they are trembling, sweaty and restless, but you cannot directly observe anxiety. When assessing the validity of a personality test, construct validity ensures that the test covers the full range of behaviours that make up the construct being measured, i.e. behaviours that contribute to the Type D Personality or a Type I Personality

Criterion Validity

Criterion validity is one of the most powerful ways to provide the validity of personality tests. Criterion validity measures how well a test correlates with an outcome. There are two types of criterion validity, and these are concurrent validity and predictive validity. Concurrent validity works by comparing test scores to an outcome to observe whether there is a correlation. Predictive validity is determined by measuring how likely a test score will predict the outcome. For example, if a personality test score correlates with actual behaviour, it is said to have high concurrent validity. If the personality test accurately predicts how well an employee will perform in the role, the test is said to have high predictive validity. 

What is the most valid personality test?

Extended DISC® is one of the most valid personality tests available. The Extended DISC profiling tool is validated and revalidated every two years. Scientifically backed through ReliaDATA our validation and reliability measures, Extended DISC® continually achieves the highest score across several validation and reliability measures. The Extended DISC® Assessment 2020 Validation Study was one of the largest yet. It included a population of 1,005,404 participants from 77 different languages and across several countries.

Construct validity refers to the extent to which a test measures what it claims to measure. The constructs measured in the Extended DISC® Assessment are the behavioural traits of Dominance, Influence, Steadiness and Compliance. The process compares the expected answers to actual answers in all 77 languages. The consistency of these scores was very high in the results from the 2020 Extended DISC® Validation Study and are supported in other studies from previous years. Extended DISC® Assessments have one of the highest construct validity scores and continue to achieve these in the two-yearly validation study.

The Extended DISC® assessment is an indicator of human behaviour. Therefore, the predictive validity analysis observes individuals’ own prediction of the dominant scale hits versus the outcome of the Extended DISC® questionnaire. According to these results, the proportion of ‘correct’ answers between the individuals’ own evaluations and the results of the Extended DISC® tool is 83.7 %. The results show the high predictive validity of the Extended DISC® Tool.