When I worked as a consultant using the MBTI®1, there was one type of call I dreaded: the calls from firms who wanted to start using the assessment in their hiring process. They’d heard about the MBTI® and its popularity in organizations. Maybe they’d even assessed some of their existing employees, with inspiring results. Now, how great would it be if they could use it to weed out all the undesirable candidates in their hiring pool?

Hiring is a time-consuming and often overwhelming process, and we’d all love a quick fix to separate the wheat from the chaff. Wouldn’t it be great if there was a simple, easy to understand tool that could tell us how an employee would perform? Of course it would. But personality type assessments are not that tool. And because I’ve had to dissuade so many of these potential clients, I’d like to give you four reasons why:

1. It doesn’t work.

You cannot tell from an individual’s personality type whether they will be suited for a particular job. This is confusing, because there is a lot of evidence to suggest that certain personality types tend to choose some occupations over others. We know, for example, that if we assess a bunch of CEOs, we’ll probably find lots of ENTJs and very few INFPs (or none at all). But if there is an INFP in the mix, does that mean she’s not cut out for her job? No. Not at all. She may be a great executive particularly because she takes a different approach from the rest of the crowd.

Anecdotes aside, there’s absolutely no data to suggest that certain personality types perform better in certain jobs than others. People may choose a job partially because of their type, but if they make an atypical choice, that’s not a recipe for disaster.

2. No, really, it doesn’t work.

Wait, didn’t we already go over that? Yes, but this is different: personality type assessments like the MBTI® and TypeFinder® literally do not work when the person taking them is under duress.

Most people who are taking a personality assessment during the hiring process want to put their best foot forward, and for that reason, assessments designed for hiring include what’s called social desirability scales: special questions intended to weed out people who are painting a bit too rosy a picture of themselves. These scales typically include statements like “I have never broken the law”—statements that overeager candidates may claim are accurate, but any truly honest person would have to admit aren't quite true.

Personality type assessments based on Briggs Myers theory are not built with any sort of indicator to red-flag candidates who are “faking good.” They also tend to include questions that are pretty transparent to the examinee. Thus, all you’re really assessing is whether the candidate understands what a good employee’s personality looks like and whether they're able to fake it.

3. It won’t warn you of real trouble.

If you’ve had the misfortune of making a really bad hire—someone who turned out to be a total nightmare for the company, for one reason or another—you might be wondering if a personality assessment could have warned you of some red flags. While there are certainly tools that can be helpful, personality type assessments are not among them.

The Briggs Myers theory is strengths-based, which means that no type is considered better than any other, and nothing potentially damning is assessed. So if you have a candidate who is dishonest, or litigious, or just plain unstable, a personality type assessment won’t pick up on any of it.

4. Even in the best case, it doesn’t tell you what you really need to know.

Personality type is an indicator of work style and core motivations, but not of skill. Even assuming that your candidate is completely open and candid with their assessment, and you get a report that accurately describes their type, all you really know is how they are likely to approach their work—not how good they are at it.

For example, most profiles of ENTJ types describe them as natural leaders. In fact, our recent research found that on average, ENTJs do tend to manage more people and earn higher salaries. You might assume, then, that if you’re looking to fill an executive position an ENTJ would fit the bill. But while a candidate’s ENTJ profile might tell you that they’ll be eager to be in charge (I’ve yet to meet an ENTJ who wasn’t), what it doesn’t tell you is whether they’ve actually gained the skills and abilities to be an excellent leader. This is a whole separate issue, and one you won’t gain any insight into with a personality type report.

Is there ever a good reason to use personality type assessment in hiring?

If you’ve been paying attention, you might have noticed that the title of this post contained a qualifier. Personality type assessment is a bad idea in hiring—most of the time. So what’s the exception?

If done correctly (and by correctly I mean with great care and consideration) a personality type assessment can be implemented during the hiring process as a useful conversation starter. That is, you may use the results of the assessment to get the candidate talking about his or her strengths, work style, motivations, and hopes for the future. You can use the framework of personality type as a starting point to structure the discussion (i.e. “We work in an open office here. How do you think that might mesh with your Introverted style?").

To do this, you must make it absolutely clear to the candidate that you are not looking for a particular result, that there are no right or wrong answers, and that the results will be discussed between the two of you as a touchpoint to your getting-to-know-you process. The key here is that you are still letting the candidate tell you about himself or herself; you are simply using the assessment to spark the discussion.

Personality type assessments sometimes get a bad rap in organizations, and I’m afraid this is partly because they are misused during the hiring process. If you love using personality type assessment with your team, do your future colleagues a favor and use it responsibly and judiciously when hiring. I promise, your team will be better for it.

What do you think about using personality type assessment during the hiring process? Have you done it? Do you have any advice for organizations who want to implement this as a standard procedure?

1MBTI® is a registered trademark of the The Myers & Briggs Foundation, which is not affiliated with TypeFinder.com.

Molly Owens
Molly Owens is the founder and CEO of Truity. She is a graduate of UC Berkeley and holds a master's degree in counseling psychology. She began working with personality assessments in 2006, and in 2012 founded Truity with the goal of making robust, scientifically validated assessments more accessible and user-friendly. Molly is an ENTP and lives in the San Francisco Bay Area, where she enjoys elaborate cooking projects, murder mysteries, and exploring with her husband and son.