How can appraisal methods deal with uncertainty?
Uncertainty can arise in the scenarios against which strategies are being tested (Section 3), the structure, timing and sequence of the elements of the strategy (Section 11), the predicted impacts of the strategy (Section 12 ), and the weights to be assigned to the individual indicators (see above). One of the simplest ways of treating appraisal is sensitivity and robustness testing. A strategy is tested against variations in a scenario, or with the model assumptions varied, or with differing weights. If the performance of a strategy is very sensitive to these changes, it is less robust, and therefore more risky. If other strategies (or schemes) perform better than it when the assumptions are varied, it may be better to select them. As with other elements of appraisal, there are more complex ways of analysing uncertainty.
