(v) Scenarios approach. Predictive models focus on predicting futures based on past
trends. These fail to recognize that the future is in many ways a result of the consequence
of present and future choices. The use of scenarios, which often relates to a backcasting
approach to decision making [10], recognizes that our society has significant control over
future outcomes, and suggests that decision making should take place in this context,
rather than viewing the future as an inevitable and hence predictable outcome. The
scenario-based approach used in the model also allows users to explore different
assumptions concerning human behaviours and values, institutions and technology, which
are seldom jointly considered in predictive models.
(vi) Address uncertainty. Models for exploring alternative futures need to address the
uncertainty surrounding the behaviour of systems in a manner that is transparent to the
user. The need to address uncertainty is especially relevant in scenario generation models
that include uncertainties from many different disciplines and that wish to consider time
frames far into the future. The scenario-based approach used includes the explicit ability
to examine how scenarios vary under different assumptions regarding specific aspects
of uncertainty, including human behaviours and values, institutions and technological
innovation. Using scenarios also provides a means to test the sensitivity of variables,
such as prices.