Risk assessments are not an exact science. Many influencing factors are unknown, requiring estimates to be made. As risk assessment is a cognitive problem, human risk perception should be considered. 

Since risk perception varies from one person to another, for an unbiased risk assessment a balanced team should be formed with several independent persons bringing in different perspectives and perceptions.

The risk manager aggregates the different opinions of the participants by averaging the various votes regarding risk impact and probability of occurrence.