11. Ideas — Discrete Types Versus Working Checklists

Overrated · the Myers-Briggs Type Indicator

The Myers-Briggs Company markets a fixed, innate "true type" among sixteen categories revealed by a short questionnaire. About 2 million people take the MBTI every year, including staff at 89 of the Fortune 100. Randy Stein and Alexander Swan reviewed the theory's evidence base in a 2019 paper. Arnau, Green, Rosen, Gleaves and Melancon tested in 2003 whether MBTI scores cluster into discrete types. They found no statistical support for discrete types — scores are continuously distributed, not bimodal. The Myers-Briggs Company's claim that newer versions fixed older reliability problems does not address that deeper finding.

Underrated · clinical checklists

Clinical culture before the mid-2000s patient-safety movement trusted expert judgement over any piece of paper. Peter Pronovost, Christine Needham, Sean Berenholtz and colleagues tested a five-step central-line checklist across 103 Michigan ICUs. The Keystone ICU project tracked 375,757 catheter-days over eighteen months, published in 2006. The median catheter-related bloodstream infection rate fell from 2.7 to 0 per 1,000 catheter-days within three months. The reduction held at 66% at sixteen to eighteen months, an incidence-rate ratio of 0.34. A near-costless checklist outperformed reliance on individual expertise.

The gap

A five-step checklist is invisible next to a personality test's sixteen codes and its corporate seminar culture. But the checklist's success is not simple: the WHO Surgical Safety Checklist, tested across eight hospitals from Toronto to Ifakara, Tanzania by Alex Haynes and colleagues in 2009, cut major complications from 11% to 7% and deaths from 1.5% to 0.8%. When David Urbach and colleagues mandated it across 101 Ontario hospitals in 2014, complications and mortality did not change significantly despite over 90% compliance — a real, published replication failure at population scale. MBTI's problem is an effect that isn't there; the checklist's is a real effect that can vanish at scale.

Example: A checklist drove US bloodstream infections to zero in Michigan but produced no measurable change in Ontario — the same idea, two outcomes, and only the second protects against overclaiming.

Verdict. MBTI's sixteen types have no statistical basis; checklists work, but not automatically everywhere, and Ontario proves it.

Overturned if: taxometric analysis found genuine bimodal clustering in Jungian-type scores, or a further population-scale trial replicated Michigan's reduction elsewhere.

Sources. 2019 · Randy Stein & Alexander B. Swan, "Evaluating the validity of Myers-Briggs Type Indicator theory," Social and Personality Psychology Compass — swanpsych.com · 2006 · Peter Pronovost et al., "An Intervention to Decrease Catheter-Related Bloodstream Infections in the ICU," NEJM — NEJM · 2014 · David Urbach et al., "Introduction of Surgical Safety Checklists in Ontario, Canada," NEJM — NEJM