[kplato] PERT distribution/risk
Jim Sabatke
jsabatke at gmail.com
Thu May 11 19:50:26 CEST 2006
Dag Andersen wrote:
> Hi, need some guidance on this.
>
> I find the following in the requirement spec:
> <quote>
> Durations are calculated for a task based on the resources assigned to
> it. The following factors need to be taken into account:
> The effort required from each resource
> The risk associated with the resource/task pairing
> The availability schedule of each resource
> The other task commitments of resources
>
> Note [Jim Sabatke]
> Allow task durations to be calculated from the following columns:
>
> "Optimistic Hours"
> "Pessimistic Hours"
> "Expected Hours"
> "Risk"
> "Duration"
>
> The "Duration" would be calculated like:
>
> "Risk" = Low Duration = (OH + 4EH +PH) / 6
> "Risk" = High Duration = (OH + 4EH + 2PH) / 7
> "Risk" = None OH = EH = PH = "Duration"
>
> If Duration is entered, then OH, PH, EH all will be set to
> "Duration" and "Risk = None"
> </quote>
>
> It's the Risk that makes me uncertain. AFAICS it's a way to handle the
> fact that some people are created more equal than others and hence,
> that the time it takes to complete a task is dependent on the
> specific resource(s) assigned to do the work.
>
> Selecting a "High" risk thus effectively says: I don't think the
> people assigned to this task is able to finish it within the normal
> estimate, so I increase the estimate.
>
> Also I think the risk must be interpreted to be for "resources
> (plural)/task pairing" and not for "resource/task pairing" as stated
> above? (Maybe what was meant anyway?)
>
> IMHO it's not the estimate that should be modified but the efficiency
> of the resource. To register this may be sensitive, though, and might
> even be illegal in certain countries?
>
Oh, one more thing. High risk is not necessarily a reflection of the
resources abilities. It could involve many other considerations, like:
- suspected inadequate design because of client uncertainty (client
expectations)
- suspected inadequate design because of client lack of experience
(client expectations)
- new technology to either the resources or the company
- new, unproven versions of software
- and etc.
Jim
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