Three-point estimation
Also called: PERT estimate, Three-point estimate
Estimating a task with an optimistic, a most likely and a pessimistic value, often combined with the PERT formula.
Definition
Instead of one number, each task gets O (optimistic), M (most likely) and P (pessimistic). The PERT formula (O + 4M + P) / 6 gives a weighted expected value, and the sums of O and P give a range for the whole job.
In practice
Test design takes 3 h at best, 4 h most likely and 7 h at worst: (3 + 16 + 7) / 6 ≈ 4.3 h.
Learn it in context
Lessons that use this term.