Page 45 -

Chapter 4
Different Modelling Purposes

Bruce Edmonds

Abstract How one builds, checks, validates and interprets a model depends on
its ‘purpose’. This is true even if the same model is used for different purposes,
which means that a model built for one purpose but now used for another may
need to be rechecked, revalidated and maybe even rebuilt in a different way. Here
we review some of the different purposes for building a simulation model of
complex social phenomena, focussing on five in particular: theoretical exposition,
prediction, explanation, description and illustration. The chapter looks at some of
the implications in terms of the ways in which the intended purpose might fail. In
particular, it looks at the ways that a confusion of modelling purposes can fatally
weaken modelling projects, whilst giving a false sense of their quality. This analysis
motivates some of the ways in which these ‘dangers’ might be avoided or mitigated.

Why Read This Chapter?
This chapter will help you understand the importance of clearly identifying one’s
goal in developing and using a model and the implications of this decision in terms
of how the model is developed, checked, validated, interpreted and described. It
might thus help you produce models that are more reliable for your intended purpose
and increase the reliability of your modelling. It will help you avoid a situation
where you partially justify your model with respect to different purposes but succeed
at none of them.

B. Edmonds ( )
Centre for Policy Modelling, Manchester Metropolitan University, All Saints Campus, Oxford
Road, Manchester, M1 6BH, UK
e-mail: bruce@edmonds.name

© Springer International Publishing AG 2017 39
B. Edmonds, R. Meyer (eds.), Simulating Social Complexity,
Understanding Complex Systems, https://doi.org/10.1007/978-3-319-66948-9_4