Differential formal analysis: evaluating safer 5-key number entry user interface designs

Differential Formal Analysis (DFA) is an evaluation method based on stochastic simulation for evaluating safety critical user interfaces with subtle programming differences. This method enforces rigorous science by requiring two or more researchers to perform the analysis which in itself, raises important issues for discussion. This method is demonstrated through a case study on 5-key number entry systems which are a safety critical interface found in various popular commercial medical infusion pumps. The results of the case study are an important contribution of this paper since it provides device manufacturers guidelines to update their device firmware to make their 5 key number entry UIs safer, as well as a method that could be applied to other designs.