TOPIC: Differentiating between Activity resource estimates, Resource breakdown structure and Project staff assignments.

Hello everyone,

Can some one clarify me the differences between Activity resource estimates, Resource breakdown structure and Project staff assignments and where are they used.

- Activity Resource Estimates: This document estimates all resources (type and quantity) related to an activity (HR, equipment etc.).You will need the resource calendar (to know which human resources are available at what time), activity list and attributes for performing this activity. You will also use the Risk Register & cost estimates to line up adequate resources.
- RBS: Resources grouped together by categories. Note - thia is a hierarchical representation. Also tied to the organisation accounting system and to the work packages in the WBS.
- Project Staff assignments: These are the actual responsibilities allocated to the aquired team (in 'aquire team process')

My Question:
1) Project schedule is an input to 'estimate cost' process as per PMBOK
2) However the output of 'estimate costs' i.e resource calendars is an input to the 'estimate activity resource estimates' How is this possible.
Are we saying that the project schedule can be created without completing the 'Estimate Resource Activity' process ? Can someone please explain this ? thanks you

I believe you can create a project schedule, which may not be very accurate at the first iteration, until you carry out all the other processes, to fine-tune your schedule.

Aung,

My question is regarding these 3 as mentioned in subject. I am confused in cost estimation, as inputs, which of these 3 will be used at what situation. If I get the differences regarding application and differences of these 3 inputs, I will be having a clear idea.

Developing the plan is not typically achieved with a single iteration through the processes, rather the plan is progressively elaborated through iterations of the planning processes.

"Project schedule is an input to 'estimate cost' process as per PMBOK, However the output of 'estimate costs' i.e resource calendars is an input to the 'estimate activity resource estimates' How is this possible. .Are we saying that the project schedule can be created without completing the 'Estimate Activity Resources' process ?"
No, I don't think so... Output from the Estimate activity resources is needed to create the schedule since the type and quantity of resources selected will impact durations. Activity cost estimates and resource calendars (including resource availability) may be rough estimates on the first iteration of Estimate Activity Resources, but elaborated and improved in accuracy in subsequent iterations (after at least one iteration through Planning Schedule, Cost and Human Resources, etc.)





Are we saying that the project schedule can be created without completing the 'Estimate Resource Activity' process ? Can someone please explain this

Project Planning is iterative in nature and progressively elaborated.

Hence these loops are expected....

Review Rita Process chart.... After Risk planning next step is "go back"....