Three-point estimating is one of the techniques in the management of a project to increase the precision of estimating durations or costs in the completion of a task by adding the dimension of uncertainty or potential risk. Three-point estimates include the following.
Optimistic (O): What may happen if all goes right
Pessimistic (P): In case the worst thing happens, consider challenges that may appear.
Most Likely (M): In case things happen according to normal standards.
The formula used in giving the final estimate is:
Estimate=6(O+4M+P)
It will lead to a weighted average and, therefore, support better planning and control of project expectations.
For Example:
Let's say you estimate the number of days it would take to finish a design activity for a given project.
Optimistic (O): If all goes well, the task could be completed in 3 days.
Negative (N): Assuming that all the delays are significant, then it would take them about 9 days.
M Most Likely: In the typical probability, it would take about 5 days.
Using the Three-Point Estimating formula:
Estimate=(O+4M+P)6\text{Estimate} = \frac{(O + 4M + P)}{6}Estimate=6(O+4M+P)
Adding the values:
Estimate=(3+4×5+9)6=(3+20+9)6=326≈5.33 days\text{Estimate} = \frac{(3 + 4 \times 5 + 9)}{6} = \frac{(3 + 20 + 9)}{6} = \frac{32}{6} \approx 5.33 \text{ days}Estimate=6(3+4×5+9)=6(3+20+9)=632≈5.33 days
