Estimating Types

Estimating Types

1.Bottom -up estimates
 -Start at the lowest level of the work breakdown structure
2.Analogous (Top-down)
-Historical data from previous similar projects
-Quicker -general idea of cost
-less accurate

3.Parametric modeling

-Mathematical
-Values


Bottom -Up estimating

1.Allowance for change
2.Best and worst case scenario
3.Most likely scenario


Three Point Estimate

O=best case Estimate
ml=most likely estimate
p=worst case estimate


e=(o+ml+p)/3


Program Evaluation and Review Technique (PERT)

O=Best case estimate
ml=most likely estimate
p=worst case estimate

e=(o+4*ml+p)/6


Estimating Work Hours

-Realistic Estimates
-Effort time
--Effort not duration
--Based on actual effort -uninterrupted
--Independent of availability
--Skills
--Named vs average resource
--Resource availablity
--75% -80%