Case Study 1: The $2 Billion MBTI Industry

The Scale

The Myers-Briggs Company (formerly CPP, Inc.) controls the MBTI. The assessment generates an estimated $2–4 billion annually through:

  • Assessment fees: Companies pay $15–40 per employee for the official MBTI assessment, with volume discounts for large organizations
  • Certification fees: Becoming a "certified MBTI practitioner" costs $1,700–$4,500, and thousands of practitioners are certified each year
  • Training materials and workshops: Licensed facilitator guides, team-building programs, and organizational development packages
  • Books and publications: The Myers-Briggs Company publishes and licenses extensive MBTI-related materials
  • Ongoing licensing: Companies must purchase new assessments for each administration; they cannot reuse materials

The financial ecosystem extends beyond the Myers-Briggs Company itself. Thousands of coaches, consultants, and trainers have built their practices around MBTI delivery. HR departments have trained staff in MBTI administration. This creates a network of people whose livelihoods depend on the continued perception that the MBTI is valid.

The Defense

When confronted with the psychometric criticisms, MBTI defenders typically make several arguments:

"It's not about the science — it's about the conversation." This is the most common defense: the MBTI's value lies in getting people to talk about personality differences, not in the accuracy of the type assignments. This argument concedes the psychometric point but claims the tool is useful anyway.

"The latest version has improved reliability." The Myers-Briggs Company has released updated versions of the MBTI (Step I, Step II, MBTI Global) with claims of improved psychometric properties. However, independent evaluations have not found substantial improvements in the fundamental problems — the type structure still doesn't appear in the data, and predictive validity remains weak.

"You have to use it correctly." This argument suggests that the MBTI's problems stem from misapplication (e.g., using it for hiring) rather than from the instrument itself. The official MBTI guidelines do warn against using it for selection purposes. But this defense doesn't address the core issues: types don't appear in the data, test-retest reliability is poor, and the instrument doesn't predict outcomes.

"Millions of people find it valuable." The popularity argument. As we discussed in Chapter 5, popularity doesn't equal validity. The Barnum effect ensures that MBTI descriptions feel accurate regardless of whether they are.

The Counter-Evidence

Pittenger (2005) review: "Cautionary comments regarding the Myers-Briggs Type Indicator" — comprehensive review finding no support for the type-based model and recommending against use in career counseling.

Boyle (1995): "Myers-Briggs Type Indicator (MBTI): Some Psychometric Limitations" — documented poor test-retest reliability and lack of construct validity.

National Research Council (1991): Committee on Techniques for the Enhancement of Human Performance concluded there was insufficient evidence for MBTI's use in career counseling.

Grant (2013): Demonstrated that continuous personality measures (like the Big Five) outperform type-based measures for predicting outcomes.

The Financial Incentive Problem

Consider the incentive structure:

  • The Myers-Briggs Company's revenue depends on organizations purchasing MBTI assessments
  • Thousands of certified practitioners have invested $1,700–$4,500 in their certification
  • HR departments have invested in MBTI training for their staff
  • Consulting firms have built MBTI-based programs into their service offerings

For all of these stakeholders, the finding that "the MBTI is not psychometrically valid" is not a neutral scientific conclusion — it is a direct financial threat. This doesn't mean they're being dishonest when they defend the MBTI. It means their evaluation of the evidence is being conducted under identity-protective cognition (Chapter 1), with the "identity" being their professional investment.

What Would Replace It?

If organizations moved away from the MBTI, evidence-based alternatives include:

  • Big Five assessments (e.g., NEO-PI-R, BFI-2, IPIP-NEO): Continuous dimensions, good reliability, predictive validity
  • Strengths-based assessments (e.g., CliftonStrengths): While also commercially driven, some have better psychometric properties than the MBTI
  • Structured interviews and work samples: For hiring, these outperform any personality assessment

The barrier isn't the availability of alternatives. It's the institutional momentum behind the MBTI and the human resistance to admitting that a $2 billion industry is built on a psychometric foundation of sand.

Discussion Questions

  1. If you were an HR director who had just learned that the MBTI is not psychometrically valid, what would you do? Consider the sunk costs, the practitioner network, and the organizational culture around MBTI.

  2. The "it's about the conversation" defense concedes the science but claims practical utility. Is this a reasonable position? Could any framework (including a random one) facilitate useful personality conversations?

  3. Should the MBTI industry be required to disclose the psychometric limitations of the instrument to purchasers? How would such disclosure affect the market?

  4. What parallels exist between the MBTI industry and other industries built on weak evidence (e.g., homeopathy, astrology services)?