The Full English Accompaniment – Psychometrics, Myers-Briggs and the pseudoscience of personality analysis

What’s piqued my interest this week?

I bloody hate the Myers-Briggs Type Indicator, the personality analysis ‘tool’ whose results I keep seeing all over the internet (1). The test beloved of HR departments, taken by 2.5 million people a year, used by 89 of the Fortune 100 (2). It seems to be used as shorthand for various perceived positive characteristics in some quarters, others try to find correlations with the FI movement, while paid-for articles use it to try to guide individuals to their ideal investments (3, 4, 5, 6). I’ve come into contact with it through work, when departments have told me my role in teams through it’s interpretation. Problem is, it’s a load of manure.

Test-retest reliability

The probability that if you resit the same test you will get the same result. Myers-Briggs own website gives figures from 75-90% for this (why the wide confidence interval?) (7). Those figures have been supported by independent research (8, 9). I can’t use a blood test, or any other scientific test, that gets the answer wrong 1/4 of the time on retest in clinical practice. Imagine if I’m checking for an infection, and tell you it’s one thing, only to retest next week and tell you it’s another. So why does it persist in public use? I’ve probably taken the MBTI four times in various setting, with three different results.

Construct validity

Myers-Briggs grew out of Jungian types in the ’40s. Jung’s theories about archetypes, types, synchronicity, the collective unconscious etc, continue to be taught today in psychology, but more as part of a history lesson and a way for people to understand themselves. They’ve been superseded and are considered by most psychologists to be unscientific, with no clear grounding of reproducible evidence (1, 10, 11). So while the Myers-Briggs sorts you into categories, there’s no actual evidence that those categories are based on anything other than theory.

Content validity 

A further flaw is the question methodology, often using black and white variables to identify which category a person falls into. Personality is not black and white. The dichotomous variables used to decide which category you fall into would be expected to result from a bimodal distribution of choices, with most people at either end of the scale. Instead we see a more normal distribution, with clustering around the middle (1, 10, 11). This invalidates the test variables; the reasons behind choices are not dichotomous, but informed by an interplay of your previous experiences, your taught and learnt behaviours and your biological wiring. The chicken crosses the road for multiple reasons, not simply to be on the other side. It’s an over-simplification of a complex construct.

 - Dilbert by Scott Adams

And that’s just for starters. There’s a huge list of criticisms and peer-reviewed rebuttals on Wikipedia (1). Much of the pro-MBTI literature is the product of poor methodology and limited scrutiny. It’s been largely sidelined by the professional community but persists in the mainstream consciousness (12). People want an easy way to understand a complex system, which is probably why HR teams around the world continue to use it, but personality is too complex to be reduced to 16 types. By all means use it as a methodology for personal reflection. Just stop trying to class others.

Have a great week,

The Shrink

Other News

Opinion/ blogs:

The kitchen garden:

What I’m reading (affiliate links):

Tombland – C.J. Sansom – I love the Shardlake series, detective novels set in the Tudor period with a crippled lead character. Beautifully written.

Food Of The Gods: The Search for the Original Tree of Knowledge: A Radical History of Plants, Drugs and Human Evolution – Terence McKenna – An ethnobotanist explores humanitys’ fascination with hallucinogenics, and the role of altered states of consciousness on the development of human society.

References

  1. https://en.wikipedia.org/wiki/Myers–Briggs_Type_Indicator
  2. https://www.psychologytoday.com/gb/blog/give-and-take/201309/goodbye-mbti-the-fad-won-t-die
  3. https://www.huffingtonpost.ca/krysten-merriman/myers-briggs-type_b_9877786.html?guccounter=1&guce_referrer_us=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_cs=-03q25v6JqVhVASPJTimXg
  4. https://www.reddit.com/r/financialindependence/comments/4gky1p/myersbriggs_of_fire/
  5. https://www.millennial-revolution.com/build/right-personality-fire/
  6. https://forum.mrmoneymustache.com/ask-a-mustachian/intj-folks-has-fire-been-the-answer/
  7. https://www.myersbriggs.org/my-mbti-personality-type/mbti-basics/reliability-and-validity.htm
  8. https://www.researchgate.net/publication/236111463_The_Myers-Briggs_Type_Indicator_Evidence_of_its_validity_reliability_and_normative_characteristics_for_managers_in_an_Australian_context
  9. https://journals.sagepub.com/doi/abs/10.1177/0013164402062004004
  10. https://www.psychologytoday.com/gb/blog/cui-bono/201603/are-scores-the-mbti-totally-meaningless
  11. https://www.theguardian.com/science/brain-flapping/2013/mar/19/myers-briggs-test-unscientific
  12. https://bit.ly/2Upya1b
  13. https://www.bbc.co.uk/news/business-47414916
  14. https://www.theguardian.com/politics/2019/mar/01/us-seeks-greater-access-to-uk-food-markets-after-brexit-trade-deal
  15. https://www.thisismoney.co.uk/money/mortgageshome/article-6742415/Mortgage-rates-begin-creep-lull-price-rises.html
  16. https://www.thisismoney.co.uk/money/bills/article-6760015/Bulb-Energy-shames-Big-Six-providers-exploitation-price-cap-cutting-prices.html
  17. https://www.thisismoney.co.uk/money/cars/article-6756471/Classic-car-experts-reveal-bangers-worth-banking.html
  18. https://moneyweek.com/502897/bond-yields-interest-rates-creeping-higher-why/
  19. https://www.bbc.co.uk/news/business-47452571
  20. https://www.cnbc.com/2019/03/01/msci-to-quadruple-weighting-of-china-a-shares-in-global-benchmarks.html
  21. https://www.theguardian.com/business/nils-pratley-on-finance/2019/feb/28/aston-martin-share-crash-shows-valuing-a-dream-takes-adjusting-to
  22. https://www.theguardian.com/business/nils-pratley-on-finance/2019/mar/05/brexit-wont-bother-the-city-but-everyone-else-should-worry
  23. http://diyinvestoruk.blogspot.com/2019/02/renewables-infrastructure-new-addition.html
  24. http://diyinvestoruk.blogspot.com/2019/03/the-uninhabitable-earth-review.html
  25. https://monevator.com/simple-maths-for-investors/
  26. https://monevator.com/the-gordon-equation-how-to-calculate-expected-returns-for-equities/
  27. https://monevator.com/robot-angels-automated-seed-investing-on-the-seedrs-crowdfunding-platform/
  28. http://www.mrmoneymustache.com/2019/02/27/how-to-create-reality/
  29. https://theescapeartist.me/2019/03/05/its-easier-without-children/
  30. https://theescapeartist.me/2019/03/09/financial-independence-is-for-everyone-part-2/
  31. https://cashflowcop.com/my-property-investment-journey-part-1-taking-in-lodgers/
  32. https://cashflowcop.com/fi-checkpoint-where-are-you-on-the-journey/
  33. http://www.frugalwoods.com/2019/02/28/this-month-on-the-homestead-when-your-internet-and-your-truck-conspire-against-you/
  34. https://www.ukvalueinvestor.com/2019/02/bae-systems-dividend-good-value.html/
  35. https://www.ukvalueinvestor.com/2019/03/buy-unilever-wake-up-rich.html/
  36. https://theescapeartist.me/2019/03/01/meet-up-friday-29-march/
  37. https://ditchthecave.com/save-the-world/
  38. https://thefemalemoneydoctor.com/ambitious-life-goals/
  39. https://thesavingninja.com/ew-betting-full-guide/
  40. https://thesavingninja.com/macro-enabled-matched-betting-spreadsheet/
  41. https://thesavingninja.com/bring-on-the-summer-savings-report-8/
  42. http://earlyretirementinuk.blogspot.com/2019/02/january-end-of-month-report.html
  43. https://www.iretiredyoung.net/single-post/2019/03/01/Early-Retirement-Costs—February-2019
  44. https://littlemissfire.com/february-2019-income-and-expenses-report-2019/
  45. https://gentlemansfamilyfinances.wordpress.com/2019/03/05/month-end-accounts-february-2019/
  46. https://gentlemansfamilyfinances.wordpress.com/2019/03/07/pension-payback-prevention/
  47. https://gentlemansfamilyfinances.wordpress.com/2019/03/09/house-price-inflation-friend-or-foe/
  48. https://gentlemansfamilyfinances.wordpress.com/2019/03/10/a-fire-argument-for-the-lisa/
  49. http://quietlysaving.co.uk/2019/03/09/meeting-up-in-manchester/
  50. https://tuppennysfireplace.com/best-frugal-foods-buy-broke/
  51. http://fiukmoney.co.uk/february-19-net-worth-and-monthly-update-7/
  52. https://drfire.co.uk/february-2019-income-expenses/
  53. https://indeedably.com/taxes-are-optional/
  54. https://indeedably.com/puppetry/
  55. https://indeedably.com/filiality/
  56. https://indeedably.com/financial-junk-food/
  57. https://youngfiguy.com/saving-sucks-or-why-you-need-a-savings-habit/
  58. https://youtu.be/BQovQUga0VE
  59. https://lovelygreens.com/pricking-out-tomato-seedlings/

2 thoughts on “The Full English Accompaniment – Psychometrics, Myers-Briggs and the pseudoscience of personality analysis

  1. Amen! I can take that test and produce any type I want, and have. Any one who is self aware can game the system to the point the test is nearly useless.

    Liked by 1 person

  2. Thanks for the shout out and another great set of links.

    I find the whole Myers Briggs thing very fascinating. That said, of course, you can’t really ‘shoe-horn’ the complexities of humans and their behaviours into just 16 categories!

    I’ve only ever done the test twice (with a 3-year gap in between) and I came out both times the same, ESTJ (the ‘Executive’). I am a little low scoring on the ‘E’ – closer to the I than to the extreme of E.

    This does make me different from the supposed norm of INTJ FI bloggers but I don’t mind being different! 🙂 Even though you consider it a load of manure, the ESTJ description is actually quite accurate for me – it describes how I work, my friendships, many of my strengths but alas also my weaknesses, some of which I only really came to recognise as I got older!

    As with many of these ‘tools’, it shouldn’t be used in isolation, only as a guide and as part of other assessment procedures.

    Liked by 1 person

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