1. MGMT 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
CPM
Renamed Precedence Diagram Method (PDM)
Uses Activity-on-Node (AON) network diagrams
PERT
Renamed Arrow Diagram Method (ADM)
Uses Activity-on-Arrow (AOA) network diagrams
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
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
Expected time
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 Figure 8-15
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.