In two-stage estimate, used orthogonal transformation to estimate aggregate average and fitting constants method to estimatevariance which was unbiased.
Suppose the estimated duration of a task is 3 months, and the variance of the estimate is 1 month.
假设估算的任务持续时间是 3 个月，并且估计的方差是 1 个月。
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In particular, the team can estimate the three values — lowest, nominal, and highest estimations — assuming that the risk was removed, and then apply these values to reestimate the project variance.