To help them with hiring decisions, some employers are choosing to use quasi-personality tests developed by industrial/organizational psychologists. The creators of popular tests tout the correlation between test scores and job performance as being at or above industry averages. But are they, and within what limits? What do the numbers used to support their claims actually mean in the real world?
When test results and job performance prediction match perfectly, the correlation coefficient (often referred to as validity) is 1, or 100%, indicating a perfect prediction of job performance. Conversely, if there is no match, the correlation coefficient is 0. The better hiring tests, in their own literature report test validity as being between approximately 0.20 and 0.50. In other words, at best, they accurately predict the impact of any particular measured candidate attribute on future job success less than 50% of the time, i.e. no better than a coin flip!
Why is the validity so low? One reason is that it is only possible for these social science tests to accurately measure a small percentage of all the factors relative to job success. Hiring tests focus on the personality attributes of the applicant, but they do not factor in all the other variables related to success such as company or department culture or outside-of-work issues.
Is there any value then to using such tests? If someone scores low on a scale which is of particular relevance to a job, it does provide a suggestion that the employer may want to explore that issue further in a face-to-face interview. However, unless the employer can learn specifically how the scale was created, plus some of its statistical characteristics relative to the scores of others succeeding in very similar jobs, the information is not helpful.
Job success is consistently better predicted when the employer first identifies the critical behaviors and skills (as opposed to personality traits) needed to thrive in a specific job situation and then compares them to those possessed by an applicant during a strong behavioral interviewing process.