Urban sustainability calls for a long-range perspective on an uncertain future. Policy analysis is a field fraught with many uncertainties. In the past decades scenario analysis has been developed as a scientific tool for coping with and managing long-run uncertainties in the policy-making process. A scenario may be defined as a possible, often hypothetical, sequence of events constructed in an internally consistent way for the purpose of focusing attention on casual processes and decision points (Kahn and Wiener, 1967). Consequently, a scenario consists normally of three parts: a description of the present situation; a description of future situations; a description of a number of events that may connect the present situation with future ones (the path) (see Nijkamp et al., 1997). The advantages of scenario methods over long-run forecasting tools are shown in Table 3.1. Progressive advantages of scenario approaches in policy analysis https://www.niso.org/standards/z39-96/ns/oasis-exchange/table">



Focus on quantified variables

More emphasis on details

Results determined by status quo

Deterministic analysis

Closed future

Statistical-econometric tests

From quantitative to qualitative

Single-track thinking

Reactive problem driven

Multiple implicit assumptions

Limited set of options

Model-determined mind

Focus on qualitative pictures

More emphasis on trends

Results based on future images

Creative thinking

Open future

Plausible reasoning

From qualitative to quantitative

Multi-track thinking

Proactive vision driven

Transparent simple assumptions

Open range of options

Alertness to signals of uncertainty

Source: Nijkamp et al. (1997)