How Personality Tests Work

The Secret to Personality Tests' Success
In 2017, Goldman Sachs started giving personality tests to internship candidates Ramin Talaie/Corbis via Getty Images
In 2017, Goldman Sachs started giving personality tests to internship candidates Ramin Talaie/Corbis via Getty Images

Some companies have nixed personality tests or specific test questions, after they caused instances of discrimination or just proved ineffective. Research shows personality tests alone don't predict job performance well. But workplace personality testing is estimated to bring in $500 million annually, and the industry is growing every year [source: Weber and Dwoskin, Meinert]. Just how successful is the MBTI? Publisher CPP provided the following statistics:

  • An estimated 50 million people have taken the Myers-Briggs assessment, and approximately 2 million people take it each year.
  • At least 89 of the Fortune 100 companies use the MBTI.

CPP declined to provide any financial data, but a 2012 Washington Post article reports that the MBTI and the various materials, certifications and training sessions related to it bring in $20 million annually. It isn't just used by corporations, either: Universities and government agencies, including the Environmental Protection Agency and the Department of State, give the assessment to their employees. According to the Society for Industrial and Organizational Psychology, 13 percent of U.S. employers use personality tests.

The reasons for this widespread success include some of the very flaws critics point out. The MBTI's positivity means that no one walks away from the test feeling bad about themselves. (CPP doesn't like it to be called a test, by the way, because "there are no incorrect answers — it's an indicator," Segovia said.) There's even a name for this: the Forer effect, first described in an experiment in which students who took a personality assessment all rated the resulting identical, positive personality profiles as highly accurate descriptions of themselves. Some of the other psychometric tests that do incorporate negative elements, like five-factor model tests, are seen as more valid by psychologists, but are less popular in workplace settings. Segovia even said that asking employees about their negative traits would be unethical and overly intrusive.

The relative simplicity of putting people into categories, rather than using a sliding, continuum-based system, also contributes to the popularity of the MBTI and similar questionnaires. "People like being told what type they are. My students snooze when I talk about the Big Five and how each trait is independent, but as soon as I say INTJ they get so excited," Shulman said.