Uniform Distribution


The uniform distribution is typically used where there is quantity uncertainty only (no scope uncertainty) and there is no standard rate or expected cost for the work.


A uniform distribution has a constant level of probability from one end of the range to the other, and zero probability outside the range.


Modelling a cost as $10,000 -10%/+20% with a uniform distribution indicates a belief that the actual cost will be in the range $9,000 to $12,000, with no particular preference for any cost within this range.


Using this distribution also indicates a belief that under no circumstances will the actual cost be outside the specified range.