LAUSR

PURPOSE Uncertainty tolerance (UT) is increasingly valued as a medical graduate attribute, and broadly measured among medical student populations. However, the validity evidence underpinning UT scale implementation has not been summarised across studies. The present work evaluates UT scale validity evidence to better inform when, why, and how UT scales ought to be used, and to identify remaining validity evidence gaps. METHODS A literature search for psychometric studies of UT scales was completed in 2022. Records were included if they implemented one of the four most cited UT scales (i.e., Physicians' Reactions to Uncertainty scale 1990 (PRU1990) or 1995 (PRU1995), Tolerance for Ambiguity scale (TFA), or Tolerance of Ambiguity in Medical Students and Doctors scale (TAMSAD)) in a population of physicians and/or medial students and presented validity evidence according to the Standards for Educational and Psychological Testing framework. Included studies were rated and analysed according to evidence for test content, response processes, internal structure, relations to other variables, and consequences of testing. RESULTS Among the investigated scales, 'relations to other variables' and 'internal structure' were the most commonly reported forms of validity evidence. No evidence of 'response processes' or 'consequences of testing' was identified. Overall, the PRU1990 and PRU1995 demonstrated the strongest validity evidence, although evidence primarily related to physician populations. CONCLUSIONS None of the studied scales demonstrated evidence for all five sources of validity. Future research would benefit from assessing validity evidence for 'response processes' and 'consequences of testing' among physicians and medical students at different training/career stages to better understand UT construct conceptualisation in these populations. Until further and stronger validity evidence for UT scales is established, we caution against implementing UT scales outside of research settings (e.g., for higher stakes decision making).