Measurement properties of the Inventory of Cognitive Bias in Medicine ICBMReport as inadecuate

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BMC Medical Informatics and Decision Making

, 8:20

First Online: 28 May 2008Received: 05 November 2007Accepted: 28 May 2008


BackgroundUnderstanding how doctors think may inform both undergraduate and postgraduate medical education. Developing such an understanding requires valid and reliable measurement tools. We examined the measurement properties of the Inventory of Cognitive Bias in Medicine ICBM, designed to tap this domain with specific reference to medicine, but with previously questionable measurement properties.

MethodsFirst year postgraduate entry medical students at Flinders University, and trainees postgraduate doctors in any specialty and consultants N = 348 based at two teaching hospitals in Adelaide, Australia, completed the ICBM and a questionnaire measuring thinking styles Rational Experiential Inventory.

ResultsQuestions with the lowest item-total correlation were deleted from the original 22 item ICBM, although the resultant 17 item scale only marginally improved internal consistency Cronbach-s α = 0.61 compared with 0.57. A factor analysis identified two scales, both achieving only α = 0.58. Construct validity was assessed by correlating Rational Experiential Inventory scores with the ICBM, with some positive correlations noted for students only, suggesting that those who are naïve to the knowledge base required to -successfully- respond to the ICBM may profit by a thinking style in tune with logical reasoning.

ConclusionThe ICBM failed to demonstrate adequate content validity, internal consistency and construct validity. It is unlikely that improvements can be achieved without considered attention to both the audience for which it is designed and its item content. The latter may need to involve both removal of some items deemed to measure multiple biases and the addition of new items in the attempt to survey the range of biases that may compromise medical decision making.

AbbreviationsICBMInventory of Cognitive Bias in Medicine

ICBM22Original 22 question version 13

ICBM1010 question-version found by authors in an earlier study

ICBM1717 question-version based on iterative removal of those items with the lowest item-total correlation

ICBMs1Scale 1 identified through factor analysis

ICBMs2Scale 2 identified through factor analysis

REIRational Experiential Inventory.

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Author: Ruth M Sladek - Paddy A Phillips - Malcolm J Bond



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