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Editorial on ‘Assessing the association between thinking dispositions and clinical error’
  1. Philip D Welsby
  1. Correspondence to Dr Philip D Welsby, 1 Burnbrae, Edinburgh EH12 8UB, UK; Philipwelsby{at}

Statistics from

Thinking that you might be wrong

The paper ‘Assessing the association between thinking dispositions and clinical error’ reminds us of our potential fallibilities.1 

The authors use a simple and simplistic task to determine Type 1 thinking preference (drug A+drug B=110 mg. Drug A is 100 mg more than drug B. What are doses of each?). i The results of these tests were compared with self-reported instances of clinical error. Only 59% of 153 clinicians reported making a clinical error in the previous 3 months. The conclusion, given several caveats, was that there was not a significant relationship between Type 1 thinking and the propensity to make clinical errors. The numbers studied were small and the test conditions were not specified.

Correct clinical decisions entail more than correct thinking. Problems have to be perceived correctly and there should be reflection with feedback.

Perceptions may be fallible

Perceptions may be fallible.2 There are three eye problems. (1) We wrongly assume we observe everything within our visual fields as if it were a detailed photograph, (2) efferent optic nerve fibres (20%) may programme the retina to influence what it informs our brains and (3) we are unaware of our blind spots. There are seven brain problems. (1) Our brains often misinterpret information presented to them, (2) occurrences seen by our non-dominant eye may be relatively neglected, (3) unexpected images (presumably those that a clinician should be particularly interested in) may be suppressed,ii (4) brains ignore substantial changes in scenarios,iii (5) we overestimate our multitasking skills, (6) our knowledge of what is normal may be limited and (7) people who are incompetent are often unaware of their incompetence as part of their incompetence—the Dunning Kruger effect.3

Thinking may be fallible

Type 1 …

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  • i The incorrect Type 1 answer (given by 67%) is 100 mg and 10 mg. The correct Type 2 answer is 105 mg and 5 mg.

  • ii Daniel Simons. 10 Mar 2010. Selective attention test [video]. (70% fail in this task).

  • iii Quirkology. 28 Apr 2007. Colour changing card trick [video].

  • iv Type 1 thinking suggests you need not change because the money is still in the same box. But you should change. When you made your choice the chance of the money being in your chosen box was one-third and the chance it was in the other two boxes was two-thirds. When Monty Hall opens the one (empty) box from the two you did not choose the chance that the remaining unopened box contains the money becomes two-thirds. So you should change. The situation of the money has not changed but the information you have has changed. When Marilyn vos Savant, whose IQ is apparently about 200, gave the correct answer ‘You should change’ in an American Journal she received considerable insulting erroneous rebuttals from so-called experts stating that she was wrong and she should leave such matters in the hands of experts like them. Nearly, the same as ‘Trust me I’m a doctor.’

  • v In England and Wales in each year, there were 30–50 homicides per million children less than 1 year old between 1982 and 1996 and this, very approximately is one in a million and therefore the chances of two infant murders, according to the previous reasoning, were 1 in 1 000 000 000 000. So the possibility of double infanticide was much more remote. In such rare situations, statistics are often useless and may be dangerous.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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