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CHP 8: Network Scheduling Technique - Coggle Diagram
CHP 8: Network Scheduling Technique
PERT
Advantages
Extensive planning
Can determine the probability of meeting deadlines by
development of alternative plans
Ability to evaluate the effect of changes in the program
Disadvantages
Decision-making ability reduced
Lacks functional ownership in estimates
Time and labor intensive
GERT
Advantages
can easily show that if a test fails
can select one
of several different branches to continue the project
Disadvantages
¯_(ツ)_/¯
Terms
Duration: The total time required to complete the activity.
Activity: The element of work that must be accomplished.
Event: Equivalent to a milestone indicating when an activity starts or
finishes.
Effort: The amount of work that is actually performed within the
duration. For example, the duration of an activity could be one month
but the effort could be just a two-week period within the duration
Critical Path: This is the longest path through the network and
determines the duration of the project. It is also the shortest amount of
time necessary to accomplish the project.
Difference between PERT and GERT
PERT uses three time estimates (optimistic, most likely, and pessimistic) to
derive an expected time. CPM uses one time estimate that represents the
normal time (i.e., better estimate accuracy with CPM).
PERT is probabilistic in nature, based on a beta distribution for each activity
time and a normal distribution for expected time duration. This allows us to
calculate the “risk” in completing a project. CPM is based on a single time
estimate and is deterministic in nature.
Slack Time(SL)
Slack can be defined as the difference between the latest allowable
date and the earliest expected date
Slack time = Latest Time - Estimated Time
Basic types of interrelationships
Discretionary dependencies
External dependencies
Mandatory dependencies