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Scheduling

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  1. MGMT 483 Week 8 Scheduling

  2. Background • A schedule is the conversion of a project action plan into an operating timetable • It serves as the basis for monitoring and controlling project activity • One of the major project management tools • Work changes daily so a detailed plan is essential • Not all activities on a project need to be scheduled to the same level of detail Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  3. Scheduling tools • Most scheduling is based on network diagrams • The diagram shows activity and event relationships and graphically portrays the sequential relationship between the tasks in a project • Clearly shows precedence – tasks that must come before or after other tasks Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  4. Network Scheduling Advantages • Consistent framework for planning, scheduling, monitoring and controlling the project • Shows interdependence of tasks • Shows when resources are needed • Ensures proper communication between parties to the project • Determines expected completion date • Identifies critical activities and those with slack Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  5. Network Scheduling Techniques • Around since the 1950s – 2 approaches initially • Critical Path Method (CPM) • Program Evaluation and Review Technique • Microsoft Project (and other software) have blended CPM and PERT into one approach Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  6. Terminology • Activity - A specific task or set of tasks that are required by the project, use up resources, and take time to complete • Event - The result of completing one or more activities • Network - The combination of all activities and events that define a project • Drawn left-to-right • Connections represent predecessors Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  7. Terminology Continued • Path - A series of connected activities • Critical - An activity, event, or path which, if delayed, will delay the completion of the project • Critical Path - The path through the project where, if any activity is delayed, the project is delayed • There is always a critical path • There can be more than one critical path Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  8. Terminology Continued • Sequential Activities - One activity must be completed before the next one can begin • Parallel Activities - The activities can take place at the same time • Immediate Predecessor - That activity that must be completed just before a particular activity can begin Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  9. The two types of network diagrams • PERT / ADM: Activity on Arrow - Arrows represent activities while nodes stand for events • CPM / PDM: Activity on Node - Nodes stand for events and arrows show precedence Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  10. AON and AOA Format Figure 8-2 Figure 8-3 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  11. Constructing the Network (AON Version) • Begin with START activity • Add activities without precedents • There will always be one • May be more • Add activities that have those activities as precedents • Continue until all activities are added Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  12. Some practice • A simple example • Question 1 – page 374 • Question 7 – page 374 (do an AON diagram) Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  13. Microsoft Project AON Network Figure 8-12 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  14. Solving the Network Table 8-1 This table shows a simple project with 10 activities and their predecessors, plus 3 time estimates for completion of the activities. Draw the AON diagram – without the time estimates Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  15. The AON Network from Table 8.1 Figure 8-14 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  16. Calculating Activity Times Expected time • The next step is to calculate expected activity completion times from the data in Table 8-1 • a=optimistic time estimate • b=pessimistic time estimate • m=most likely time estimate Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  17. The Activity Expected Time Results Table 8-2 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  18. Critical Path and Time The nodes now show the activity, plus the Expected time, followed by the Variance Treating the expected times as certain - how long will it take to complete the project? What is the critical path – ie the longest path through the project Figure 8-15 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  19. The critical path • The project will take 43 days (this is the shortest time it can possibly take) • The critical path is a – d – j • If any of these activities take longer than the expected time, the project will be late Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  20. Critical path problem • Question 8 – page 375 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  21. Critical Path and Time – ES, EF, LS, and LF shown on the network diagram ES = Earliest Start EF = Earliest Finish LS = Latest Start LF = Latest Finish Figure 8-16 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  22. Slack • Slack (aka, Float) – In the previous section, the earliest possible dates for each activity were determined. • By starting the analysis at the end of the network and working through it backwards, the latest possible dates for each activity can be determined. • The difference between the early dates and the late dates is float or slack. • Activities on the critical path have zero float. Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  23. Slack Values Table 8-3 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  24. An example AON diagram showing ES, EF, LS,LF, slack and activity duration Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  25. Problem – calculating ES,EF, LS, LF, slack, and duration • Problem 19 on page 377 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  26. Precedence Diagramming • Precedence Diagramming – The Precedence Diagram Method allows for additional relationships to be established between activities. They are: • Finish to Start – The successor activity cannot begin until the predecessor finishes. This is the most common relationship depicted in networks. • Start to Start – The successor activity cannot begin until the predecessor begins. • Finish to Finish – The successor activity cannot finish until the predecessor activity finishes. • Start to Finish – The successor activity cannot finish until the predecessor activity starts. This relationship is rarely used. Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  27. Precedence Diagramming Conventions (MS Project) Figure 8-17 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  28. MS Project Gantt Chart version of the project described in Table 8-1 (page 344) Figure 8-18 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  29. Same data presented as an AON Network in MS Project Figure 8-19 Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  30. Uncertainty of Project Completion Time • The chance of completing a project within a given time period can be calculated. • The project activities are assumed to be statistically independent • The variance of a set of activities is equal to the sum of the variances of the individual activities • We are particularly interested in variances on the critical path Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.

  31. Uncertainty of Project Completion Time - example • The chance of meeting a particular project duration can be calculated as: D = the desired project completion time µ = the critical time of the project, the sum of the TEs for activities on the critical path = the variance of the critical path, the sum of the variances of activities on the critical path Z = the number of standard deviation of a normal distribution (the standard normal deviate) Meredith & Mantel (2009) Project management: a managerial approach. 7th ed. Wiley.