The use of mathematical models to support decision-making is proliferating in both the public and private sectors. Advances in computer technology and greater opportunities to learn the appropriate techniques are extending modelling capabilities to more and more people. As powerful decision aids, models can be both beneficial or harmful. At present, few safeguards exist to prevent model builders or users from deliberately, carelessly, or recklessly manipulating data to further their own ends. Perhaps more importantly, few people understand or appreciate that harm can be caused when builders...