The required confidence level is the probability (confidence) required by the VSP user that the decision rule used will correctly indicate that the required fraction of values is less than the action level. For example, if the required confidence level is specified to be 0.95 (95%) and the required fraction of the population that must be less than the action level is 0.90 (90%), then the VSP user requires that the probability be at least 0.95 that at least 90% of the population values are less than the action level when that decision is made using the upper tolerance limit. Conversely, the VSP user is willing to tolerate at most a probability of 0.05 (5%) that less than 90% of the population values will be less than the action level.