Two experts in the field of delirium in older adults confirmed the validity of both the questionnaire and its correction so as to ensure that the concept of delirium was measured accurately. Following this validation, the questionnaire was pretested on three nurses with the same profile/characteristics as the RN population targeted for the study. The aim of this process was to be certain that the questions and also the structured clinical vignettes were sufficiently clear and that the sufficient time had been allocated to complete them. The nurses who took part in the pretesting were a part of the final sample for this research.