We have released our uncertainty index calculator so that stakeholders can monitor our measure of uncertainty. We use the uncertainty index to select a WACC point estimate. If our uncertainty index is within one standard deviation of the long term average, we select the midpoint of our range of WACC estimates. If the uncertainty index is more than one standard deviation from the long-term average, we would consider moving away from the midpoint WACC.Note that SPSS, MS Excel and proprietary data from Bloomberg and Thomson Reuters Datastream are required to calculate our uncertainty index.