Hiring employees is one of the most difficult actions you can undertake. You work with little data and usually have to make a relatively quick decision that will have major implications for your company and cost you significant amounts of money on an ongoing basis. Few other things can improve or hurt your operations and bottom line so much.

It's understable then that you might turn to a personality evaluator like the Myers-Briggs Type Indicator (MBTI), which classifies people into 16 personality types, to hire the right employees for the right job. But that doesn't mean it's the right move.

What Myers-Briggs Can't Do

According to an email from Myers-Briggs, CPP, there are many people who misunderstand and misuse the MBTI. The first and probably largest fallacy is that the evaluation can tell you whether a person is a good fit for a particular role.

In fact, the firm says that using the MBTI as part of hiring is unethical. An assessment is supposed to be voluntary. If you force people to take a psychological test, you're essentially saying that you expect all aspects of their lives to be open to your scrutiny and use. It's a great way to tank morale and scare off many talented candidates you might otherwise attract.

Even more, the idea of predicting success in a job from a set of psychological inclinations is a bit crazy. As Myers-Briggs states: "Furthermore, people of many different types excel at the same job for different reasons. Individuals should not be pigeonholed based on their personality preferences."

For example, you might assume that introverts are poor candidates for stressful, high visibility jobs. Like Steve Jobs. Yes, the late CEO of Apple exhibited "behavior indicating a preference for introversion." The introverted/extroverted scale is not about whether someone is shy or gregarious. It addresses whether people gain energy from being by themselves or among others.

Myers-Briggs argues that the "MBTI tool can't tell you who to hire, but it can help you work with your team so that everyone gives his or her best performance." And there might be something to that. Understanding how people communicate, interact, and collaborate should help you better run your company.

There's just one problem. As the firm says, taking the test should be voluntary and the results belong to the test taker. So, if people are willing to take the MBTI and share their results, that's fine. However, if you coerce them into participation, you've got the same problem as using the evaluation as a hiring tool.

Plus, there has been significant criticism of the test by psychologists for years, including a significant chance that taking it twice could show different results. So maybe the best thing is to give up on the presumptions and get back to the hard work of trying to get to know an applicant the old-fashioned way.