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PERT and CPM are complementary tools, because "CPM employs one time estimation and one cost estimation for each activity; PERT may utilize three time estimates (optimistic, expected, and pessimistic) and no costs for each activity. Although these are distinct differences, the term PERT is applied increasingly to all critical path scheduling." [3]
In probability and statistics, the PERT distributions are a family of continuous probability distributions defined by the minimum (a), most likely (b) and maximum (c) values that a variable can take. It is a transformation of the four-parameter beta distribution with an additional assumption that its expected value is
The E and SD values are then used to convert the project time estimates to confidence intervals as follows: The 68% confidence interval for the true project work time is approximately E(project) ± SD(project) The 90% confidence interval for the true project work time is approximately E(project) ± 1.645 × SD(project)
Additionally, each task has three time estimates: the optimistic time estimate (O), the most likely or normal time estimate (M), and the pessimistic time estimate (P). The expected time (T E) is estimated using the beta probability distribution for the time estimates, using the formula (O + 4M + P) ÷ 6.
If the cost of each unit of time in the diagram above is $10,000, the drag cost of E would be $200,000, B would be $150,000, A would be $100,000, and C and D $50,000 each. This in turn can allow a project manager to justify those additional resources that will reduce the drag and drag cost of specific critical path activities where the cost of ...
John Kingman gave a formula for the mean waiting time in a G/G/1 queue, now known as Kingman's formula. [ 17 ] Leonard Kleinrock worked on the application of queueing theory to message switching in the early 1960s and packet switching in the early 1970s.
Budgeted cost of work performed (BCWP) also called earned value (EV), is the budgeted cost of work that has actually been performed in carrying out a scheduled task during a specific time period. [1] The BCWP is the sum of the budgets for completed work packages and completed portions of open work packages, plus the applicable portion of the ...
In project management, float or slack is the amount of time that a task in a project network can be delayed without causing a delay to: [1]: 183 subsequent tasks ("free float") project completion date ("total float"). Total float is associated with the path.