Accuracy of Estimates
Accuracy of Estimates
(OP)
Are there some rules of thumb for accuracy of estimates at various stages of engineering, like ballpark, back of envelope, preliminary engineering, detailed engineering, etc? Seems like I have seen figures from 250% going down to 10% as engineering effort is expended.





RE: Accuracy of Estimates
Type of cost estimation Usual reliability
1. Order -of-magnitude + ,- 30 to 60 %
2. Study + , - 30%
3. Preliminary + , - 20%
4. Definitive project control + , - 10%
5. Detailed estimate + , - 5%
As you know , we have 5 standard cost estimation.
Hope this help