This paper describes how simulations can be used to reason about the impact of user interface design features in exploring the effect of different contexts of use on the occurrence of technology-induced errors. The paper describes our approach in several phases, using an example from the analysis of technologyinduced errors in medication administration. In the initial phase a clinical simulation is conducted to gather baseline data on the occurrence of technologyinduced error using the technology under study. In this phase of the study, data arising from the clinical simulation are collected and then analyzed using qualitative and quantitative approaches to assess the relationship between aspects of interface design (i.e. usability problems) and rates of technology-induced error. In the next phase, the base rates for error associated with specific types of usability problems (from the initial phase) form the input into computer-based mathematical simulations. This approach links clinical simulations with computer-based simulations and demonstrates the potential impact of aspects of interface design and contextual factors upon medical error along with the implications for correcting interface design issues.