Impact is the result of the occurrence of an event on the project either positive or negative. (This could include a schedule delay due to a specific event that may have a high negative impact; increased access to a construction site due to early departure of occupants in an office space may have a positive impact on a project).
The impact columns represent the cost impact as a result of the risk occurring, and are assessed on 10th percentile, typical and 90th percentile.
If there were a hundred projects, the 10th percentile would represent the average impact of the 10 projects with the lowest cost impact as a result of the risk occurring.
The 90th percentile would represent the average of the 10 projects with the highest cost impact as a result of the risk occurring.
The Typical column represents the most likely cost impact of the remaining projects as a result of the risk occurring.