Background The field of paramedicine continues to advance in scope. Simulation training is frequently used to teach and evaluate students. Simulation examinations are often evaluated using a standardized global rating scale (GRS) that is reliable and valid. However, the effects of differential rater function over time (DRIFT) have not been evaluated on the GRS during simulations. This study aimed to assess if DRIFT exists during a GRS.

Methods Data was collected at Collège Boréal, Sudbury, Ontario, Canada during the 6 simulation evaluations within the scholastic year. Raters were randomly assigned to evaluate several students at the same station. Each station lasted 12-minutes in length and there was a total of 11-stations. A model to test the scores of DRIFT was created and was tested against both a leniency and perceptual model to explain DRIFT.

Results Amongst the explored alternatives, a model that included students, the rater, and the dimensions had the greatest evidence (-3151 Bayes Factors). This model was then tested against leniency (K= -9.1 dHart) and perceptual models (K= -7.1 dHart) suggesting a substantial finding against DRIFT, however, the tested models used a wide parameter, therefore, the possibility of a minor effect is not fully excluded.

Conclusion DRIFT was not found; however, further studies with multiple centres and longer evaluations should be conducted.