The schedule management plan
defines the method used and the level
of accuracy along with other criteria
required to estimate activity
durations including the project update
cycle.
Activity list
The activity list identifies
the activities that will
need duration estimates.
Activity
attributes
The activity attributes provide the
primary data input for use in
estimating durations required for each
activity in the activity list.
Activity resource requirements
The estimated activity resource requirements will
have an effect on the duration of the activity, since
the level to which the resources assigned to the
activity meet the requirements will significantly
influence the duration of most activities.
Resource calendars
The resource calendars influence the
duration of schedule activities due to the
availability of specific resources, type of
resources, and resources with specific
attributes.
Project scope statement
The assumptions and
constraints from the project
scope statement are
considered when estimating
the activity durations.
Risk
Register
. The risk register provides the list of risks,
along with the results of risk analysis and risk
response planning
Resource breakdown structure
The resource breakdown structure provides a
hierarchical structure of the identified resources by
resource category and resource type.
Enterprise environmental factors
The enterprise environmental factors that can
influence the Estimate Activity Durations process
include, but are not limited to: • Duration estimating
databases and other reference data, • Productivity
metrics, • Published commercial information, and
• Location of team members
Organizational process assets
The organizational process assets that can
influence the Estimate Activity Durations process
include, but are not limited to: • Historical duration
information, • Project calendars, • Scheduling
methodology, and • Lessons learned.
Expert judgement
guided by historical information, can
provide duration estimate information
or recommended maximum activity
durations from prior similar projects.
Expert judgment can also be used to
determine whether to combine methods
of estimating and how to reconcile
differences between them.
Analogous
estimating
Analogous estimating is a technique for estimating the duration or
cost of an activity or a project using historical data from a similar
activity or project. Analogous estimating uses parameters from a
previous, similar project, such as duration, budget, size, weight,
and complexity, as the basis for estimating the same parameter or
measure for a future project.
Parametric estimating
is an estimating technique in which an algorithm is used to
calculate cost or duration based on historical data and
project parameters. Parametric estimating uses a statistical
relationship between historical data and other variables
(e.g., square footage in construction) to calculate an
estimate for activity parameters, such as cost, budget, and
duration.
Three-point estimates
PERT uses three estimates to define an approximate
range for an activity’s duration: •Most likely (tM). .
•Optimistic (tO), . •Pessimistic (tP).
Group decision-making techniques
Team-based approaches, such as brainstorming, the Delphi or
nominal group techniques, are useful for engaging team members
to improve estimate accuracy and commitment to the emerging
estimates
Reserve analysis
Duration estimates may include contingency reserves, sometimes referred to as time reserves
or buffers, into the project schedule to account for schedule uncertainty. Contingency reserves
are the estimated duration within the schedule baseline, which is allocated for identified risks
that are accepted and for which contingent or mitigation responses are developed.
Contingency reserves are associated with the “known-unknowns,” which may be estimated to
account for this unknown amount of rework.
Activity duration estimates
Activity duration estimates are quantitative
assessments of the likely number of time
periods that are required to complete an
activity.
Project documents updates
Project documents that may be updated include, but
are not limited to: • Activity attributes; and •
Assumptions made in developing the activity duration
estimate, such as skill levels and availability, as well as a
basis of estimates for durations.