Introduction This paper reports on the development of a scale to measure intrapersonal factors (IPF) that may influence speaking up behaviour in the operating room.

Methods Participants were postgraduate year 2, 3, and 4 anaesthesiology residents and practising faculty anaesthesiologists at a large quaternary care academic hospital. Based on a literature review, the authors constructed the initial scale. Exploratory factor analysis was conducted to identify the underlying factor structure for the scale. A set of one-way ANOVAs and multiple ordinal regressions were carried out to provide additional validity evidence for the new scale.

Results Exploratory factor analysis indicated a three-factor solution accounting for 73% of the variance. The self-efficacy subscale included four items (Cronbach’s α = 0.86), and the social outcome expectations (Cronbach’s α = 0.86) and assertive attitude (Cronbach’s α = 0.67) subscales contained three items each. The effect of training level was significantly associated with self-efficacy (p < 0.001) and assertive attitude subscale scores (p < 0.001). Multiple ordinal regressions indicated that IPF predicted participants’ likelihood of speaking up in various hypothetical scenarios.

Discussion Our analyses provided initial evidence for the validity and reliability of a 10-item IPF scale. This instrument needs to be validated in other cohorts.