Visualization and model formulation: an analysis of the sketches of expert modellers

We report on an exploratory study of the use of sketches by experts engaged in the formulation of operational research models, We outline a methodology to identify sketches, link them to text in an associated verbal protocol, classify them, and relate their use to the modelling process. We found that use of sketches is part of the personal modelling style of experts, that sketches are used more when the focus is on model structure or realization than on model context or assessment, that sentential sketches tend to be started sooner than diagrammatic sketches, and that sketching generally begins earlier on more difficult problems. We expect that such descriptive studies of expert behaviour will be useful in developing a science of modelling and in teaching novice modellers.