How doctors conceptualise P values: a mixed methods study



Publication Details

Tam, C. Wah Michael., Khan, A., Knight, A., Rhee, J., Price, K. & McLean, K. (2018). How doctors conceptualise P values: a mixed methods study. Australian Journal of General Practice, 47 (10), 705-710.

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Royal Australian College of General Practitioners

Additional Publication Information

Abstract reproduced with permission from the RACGP


Background and objectives: Researchers and clinicians have been criticised for frequently misinterpreting and misusing P values. This study sought to understand how general practitioners (GPs) in Australia and New Zealand conceptualise P values presented in the manner typically encountered in a medical publication.

Methods: This mixed-methods study used quantitative and qualitative questions embedded in an online questionnaire and delivered through an Australian and New Zealand GP-specific Facebook group in 2017. It included questions that elaborated on the participant's conceptualisation of 'P = 0.05' within a scenario and tested their P value interpretation ability and confidence.

Results: There were 247 participants who completed the questionnaire. Participant conceptualisations of P values were described using six thematic categories. The most common (and erroneous) conceptualisation was that P values numerically indicated a 'real-world probability'. No demographic factor, including research experience, seemed associated with better interpretation ability. A confidence-ability gap was detected.

Discussion: P value misunderstanding is pervasive and might be influenced by a few central misconceptions. Statistics education for clinicians should explicitly address the most common misconceptions.

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