Representations of equation-based models are not created equal

For equation-based modelling languages, modelling experts have many degrees of freedom when building a model from scratch. One of the most basic choices the expert faces is the mode of representation. The same system can be represented for instance as a block-diagram, by writing down the physical equations, by writing an algorithm, or by graphically connecting ready-made subcomponents. To give some guidance in this aspect, an experiment was conducted to measure the effects of different representations on various tasks. Participants had to identify models and predict their transient response. Both the time to execute the task and the correctness of the answer were measured. Participants also had to rate their confidence regarding the models. Results showed that tasks were executed much faster for graphical representations than for block-digrams. Equation-based and algorithm-based models can be grouped in the middle. The same results hold for rated confidence. Interestingly, the amount of errors was similar for all representations. Apparently, modelling experts largely compensate for difficulty by taking their time.