It’s Not Just a Matter of Opinion

Evidence as to why Type criticisms are misguided and how we can respond

by Penny Moyle and John Hackston

IT’S NOT JUST A MATTER OF OPINION: EVIDENCE AS TO WHY TYPE CRITICISMS ARE MISGUIDED AND HOW WE CAN RESPOND PENNY MOYLE (ENTJ) AND JOHN HACKSTON (INTP)Ever heard or read criticisms of type instruments, in particular the MBTI® assessment? It’s a rhetorical question; the MBTI® is regularly damned in both academic literature and the popular press. Last summer we experienced a new spate of negative press triggered by the publication of a biography of Isabel and Katherine by Merve Emre[i]. This included claims that the MBTI® is not reliable and that “it is a well-known fact that the type indicator is not scientifically valid” (page xv). Book reviews repeated and amplified this assertion.

Yet if the MBTI® is so flawed, why is it the most famous personality questionnaire in the world, taken by millions of people every year? Have tens of thousands of practitioners and millions of their clients been taken in by a scam, or is something else going on? Though the long history and popularity of the MBTI® make it a target, most of these criticisms could equally be levelled at type assessments more generally, and even other personality questionnaires.

In 2018, we published a scholarly article[ii] responding to these questions, in the well-respected peer-reviewed Journal of Personality Assessment. In our Conference session we will draw on this, demonstrating why many common criticisms of type assessments are either unfounded or misguided, including:

  • Trait versus type: the claim that personality is better described by continuous, normally distributed traits than by discontinuous types. We’ll show how this criticism is rooted in misunderstandings and stereotyping of type theory and the concept of preference.
  • Poor reliability, especially test-retest reliability. We’ll present evidence that the MBTI® in fact has very good reliability and show where the misconception of “poor reliability” comes from.
  • Lack of predictive validity. We’ll identify and refute three misconceptions that have led to this criticism and show how validity has been amply demonstrated.
  • Poor factor structure, neglecting neuroticism. We’ll discuss why the absence of neuroticism is a spurious criticism, and touch on other evidence for and against the factor structure of the MBTI®.
  • Responses to the MBTI® can be faked, like all self-report questionnaires. We’ll show why this is not a problem for the MBTI®, used exclusively for personal development.
  • Barnum effects: the MBTI® is often criticised for being overwhelmingly positive, with type descriptions seeming insightful but applying to everyone. We will share evidence that this is not the case.

There is a common theme behind many of these criticisms; academics and other reviewers use validity and other criteria developed to assess the suitability of assessments for use in selection, but these do not describe the whole picture in establishing the validity of instruments intended for use in development. Assessments like the MBTI®, designed only for developmental use, therefore, often get a bad press in the academic literature. We’ll show how traditional criteria, especially regarding validity, need to be adapted for development use, and lay out additional criteria, such as simplicity and positivity, that are not typically discussed in academic reviews. In particular, we will describe the new concept of ‘experiential validity’, the extent to which an assessment achieves the desired outcome for the end-user, calling for more research on this previously neglected aspect of validity.

In presenting this session at the BAPT Conference, we know that we will be talking to an experienced and informed group of practitioners. So this won’t just be a presentation; we will make it as interactive as possible, and include opportunities for you to share your views with us and other participants.  We hope you will leave the session, not only with a better understanding of the issues, but equipped to respond to them when they arise in the course of your work with type.

[i] Emre, M. (2018): What’s Your Type:  The Strange History of Myers-Briggs and the Birth of Personality Testing. London: William Collins.

[ii] Moyle, P. and Hackston, J (2018): Personality assessment for employee development: Ivory tower or real world. Journal of Personality Assessment. 100 (5), 507-517

About the Authors

Penny Moyle (ENTJ) 

Dr Penny Moyle
Dr Penny Moyle

Penny is a business psychologist, combining a background in both academic and commercial research with decades of consulting and training experience, as well as hands on experience of management, including as CEO of OPP Ltd (2011-2017). The MBTI® has been her assessment of choice for employee development for over 20 years. Email:

John Hackston (INTP)

John Hackston
John Hackston

John is Head of Thought Leadership at The Myers-Briggs Company. He is a Chartered Psychologist with over thirty years of experience in helping clients to use psychometric tests and questionnaires. He carries out research to bring personality assessments, in particular the MBTI®, to life, helping practitioners and end users apply the insights they gain both inside and outside work. Email:

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