Enterprise environmental factors in this context refer mainly to historical information and databases as base for analogous estimates (comp. PMBOK3, page 140).

• And Organizational process assets in this context refer to specific collections of generalized data as base for analogous estimates (comp. PMBOK3, page 140).

(3.4) Activity Duration Estimating

(3.4.1) Process Input

... generated by predecessor processes

... introduced by external units

  • Enterprise environmental factors
  • Organizational process assets

(3.4.2) Process Definition

Activity duration estimating is the process for "[...] estimating the number of work periods that will be needed to perform each schedule activity" (comp. PMBOK3, p. 123). Duration can be estimated in units being freely defined by the project. And the durance often is also influenced by the power of the resources and vice versa. Therefore resource estimating und duration estimating as processes should be connected. This includes, that " the duration estimate is progressively elaborated" (comp. PMBOK3, p. 139).

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

(3.4.3) Tools and Techniques

PMBOK Mentioned Methods

  • Expert judgement is used to determine how long an activity might be.
  • Analogous estimating is a method for estimating by comparing the actual unit with similar already realized / executed units. Therefore "analogous estimating uses historical information and expert judgement".
  • Parametric estimating computes the durances by formulars which operates on more or less unsure values
  • Three-point estimating is a method which estimates not only one value (here: of durance), but the value, which most likely will be reached, and an optimistic value and a pessimistic value. And on the base of these estimated values the method computes variances and probabilities
  • Reserve analysis is the process of computing a reserve into the estimated results. These reserved buffers and the method for computing it are explicetely documented and not hidden.

(comp. PMBOK3, p. 142)

Open Source Tools

  • myPmpsFactory offers a structured template for activity lists which allows to insert the durations (work 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 durations of the activities.

(3.4.4) Process Output

  • Activity Duration Estimates are estimated durances for each activity given as values (ranges are indicated by +...- addons or percent failure values)
  • Updates of Activity Attributes are evoked by this process, because the estimated durance of an activity is an attribute of the activity and must be documented.

(comp. PMBOK3, p. 142)

(3.4.5) Output Using Successor Processes

Successors using the initially generated output as own input(1):

Processes using the updates as input(2):

  1. For details see FAQ::Q001:1
  2. For details see FAQ::Q001:2