I think Bottom Up estimation technique is most appropriate, but it also depends on circumstances, I am agree with Deepesh, that using multiple/combination/hybrid approach will definitely help in build most realistic estimation. Saving Changes...
Mahabubur RahmanProject Manager Structures-Bridges| Department of Infrastructure, Government of Nothwest TerritoriesYellowknife, Northwest Territories, Canada
I agree with Deepesh. Most probably, bottom-up could be a good approach if you have enough time and a detail WBS along with similar project experience. Saving Changes...
Paul VisserProject Manager, PMP, ITIL, TMForum| Huawei TechnologiesMadrid, Spain
Agree with Deepesh, a combination is the best solution, using a combination of techniques and to benefit form available information and experience. Saving Changes...
Bottom up estimation usually provides most accurate estimates. Still, as Deepesh mentioned, you can use a combination of estimation techniques. Saving Changes...
I can see some specific cases where parametric would work well - once you have a very good handle on what it takes to install one server for example, doing multiple servers of the exact same configuration might be estimated in that manner. Otherwise, as the others indicated a combination of top-down and bottom-up methods would be recommended.
Kiron Saving Changes...
Stéphane ParentSelf Employed / Semi-retired| Leader MakerPrince Edward Island, Canada
Parametric can be invaluable for estimating material resources, like server sizes/number, network bandwidth, and so on . It becomes a little less useful for estimating infrastructure activities such as preparation, installation and testing.
The one exception is when the infrastructure team is always the same and available. Saving Changes...
Anish AbrahamPrivacy Program Manager| University of WashingtonAuburn, Wa, United States
I would go with bottom-up, but the combination of top-down and bottom-up would be the ideal choice, as suggested by all. Saving Changes...
