As with the assessment of likelihood, a valuable way of assessing impact would be the creation of categories of impact as follows:
Negligible. No risk of injury, low $ loss, small delays, no reputation impact
Easily remedied, medium $ impact
High $ loss, capability impaired, moderate impact on reputation
Major $ loss, major impact on reputation
Extreme $ loss (bankruptcy), huge political impact, total loss of reputation
The end result of the evaluation process would be to classify each event with a probability figure (1 to 5), and an impact figure (A to E).
Just as it is critical to involve as many people as possible in the identification phase, a variety of people should be involved in the evaluation phase. Not everyone has the same views of whether a particular event is likely to occur, or the impact that event would have on the business. By getting a number of viewpoints a truer picture of the risk invariably arises.