Defining Uncertainty for Lags

[G&G]

What are the Low, Base and High fields used for in the Predecessor tab?

[Intaver Support]

The Predecessor tab, which is located in the Task Information dialog box, is the central view for defining task predecessors. As well as defining predecessor link (Task ID, Name, and Type) you can also define the lag between the predecessor and successor as a 3pt uncertainty.
To add the uncertainty to a lag, open the Task Information > Predecessor tab. Enter in a low, base (most likely), and high estimates in days and select a statistical distribution from the Distribution drop-down list.