• There seems to be an hen and egg problem in the PMBOK®: This process Activity Resource Estimating requires the Resource Availability as input, which is generated by the processes Acquire Project Team and Select Sellers. But these both processes themselves require the output of Cost Budgeting which itself requires the output of the process Activity Duration Estimating and also the output of this process Activity Resource Estimating. Hence there exists a loop. By breaking our own rule for discovering the sequential structure of the project management process we assume, that the processes Acquire Project Team and Select Sellers which are members of the Executing Process Group shall be the successors because normally the execution follows the planning.

Enterprise environmental factors in this context refer to the "infrastructure resource availabilty information"  (comp. PMBOK3, page 136).

• And Organizational process assets in this context refer to the "[...] policies of performing organization regarding staffing and the rental or purchase of supplies and equipment that are considered during activity resource estimating" (comp. PMBOK3, page 136)

• Resources are not only materials but also human beings who execute the task dissipating the materials. Sometimes the durance of a task is inversely proportional to the number of acting people. Therefore activity resource estimating and activity duration estimating are two processes which initially may be executed parallely while the intermediary results will be interchanged

(3.3) Activity Resource Estimating

(3.3.1) Process Input

... generated by predecessor processes

... introduced by external units

  • Enterprise environmental factors
  • Organizational process assets

(3.3.2) Process Definition

Activity Resource Estimating is the process for "[...] estimating the type and quantities of resources required to perform each schedule activity" (comp. PMBOK3, p. 123): one has to determine, "[...] what resources (persons, equipement, or materiel) and what quantities of each resource will be used"  (comp. PMBOK3, pp. 135f)

The subject Time operates on the base of other time concerning concepts

(3.3.3) Tools and Techniques

PMBOK Mentioned Methods

  • Expert Judgement is used for determining which material and which skills and how many of them are necessary to execute an activity.
  • Alternatives analysis tries to find other solutions.
  • Publishing estimating data contains published information about production rates and so on.
  • Project management software is often used to plan resource pools, to develop resource estimates, to organize resource breakdown structures and to offer resource calendars to the project manager.
  • Bottom-up estimating is the method, by which a global unit (here the activity) is decomposed into smaller pieces, which can be reasonable estimated and whose single values can be added bottom up to the searched global value.

(comp. PMBOK3, p. 137)

Open Source Tools

  • myPmpsFactory offers a structured template for activity lists which allows to insert the costs (man days) of the activities. This template can be edited by Open Office 3 (Calc).
  • Planner offers a project schedule file which also allows to insert the costs (man days) of the activities.

(3.3.4) Process Output

  • Activity Resource Requirements document the resource requirements for all activities, which than "[...] can be aggregated to determine the estimated resources for each work packages".
  • Updates of Activity Attributes will surely be evoked, because the estimated resource requirements are activity attributes and must therefore be integrated into those documents.
  • The Resource Breakdown Structure "[...] is a hierarchical structure of the identified resources by resource category and resource type"
  • Resource Calendars will be generated or updated. They list working periods, availiability periods and idle periods of the resources
  • Requested Changes might be necessary in comparing scope and other parts of the project management plan with the reality of the resources.

(comp. PMBOK3, p. 138)

(3.3.5) Output Using Successor Processes

Successor processes using the initially generated output(1)

Successor processes using the updated output(2)

  1. Each of these successor (sub-)processes is connected to the (sub-)process of this page by a specific acyclic path of other sub-processes. These links constitute the main structure of the whole project management process as directed graph.
  2. Each of these successor (sub-)processes is connected to the (sub-)process of this page by a maybe cyclic path of other sub-processes. Therefore these successor could also be predecessors of this process. These type links constitute the necessary loops in the whole project management process.