1. Critical Path Method(CPM)

2. Critical Path Method (CPM)
A project planning and scheduling technique
CPM is part of group of techniques called Network Models
CPM is broken into:
Creating Work Breakdown Structure
Creating a Network Diagram of the Project
Computing Activity Times and Activity Total Float
Computing the Project Duration and Critical Path
Creating an Activity Schedule Table
Creating a GANTT Chart Schedule

3. Work breakdown structure (WBS)
Figures Work breakdown structures

4. Product breakdown structure (PBS)
Figures 8.5 – 8.8 Product breakdown structures

5. Product flow diagram
Figure 8.9 PRINCE2® product flow diagram

6. Quality/completion criteria Can add:
Product description
Purpose
Composition
Derivation
Quality/completion criteria
Can add:
Format
Related products
Review methods

7. Work packages
Figure Work packages for a training course

8. Linear responsibility chart
Figure Linear responsibility chart

9. Establishing Activity Precedence
Code
Activity
Immediate Predecessors A
Draft Req. Catalogue B
Review Req Catalogue C
Draft data flow diagram D
Interview Notes E
Agreed data flow diagram
Some activities must be down before others

10. Network diagram (activity-on-arrow)
Figure Network diagram (activity-on-arrow format)

11. Network with durations & critical path
Activities if delayed will delay the whole project (the activities with the longest path)
Figure Network diagram with durations & critical path added

12. Activity Times
Activity Earliest Start Time (EST)
Activity Earliest Finish Time (EFT)
Activity Latest Start Time (LST)
Activity Latest Finish Time (LFT)

13. Network diagram (activity-on-node)
EFT
Activity Name
EST
Activity Duration
LST
LFT
Figure Network diagram (activity-on-node format)

14. Effort and elapsed time
Effort = total volume of work
Elapsed time depends on effort and also:
How many resources are available
What proportion of their time is available to the project
Delays outside the team’s control (eg lead times for hardware)
Dependencies on others

15. Activity Total Float
Is the amount of time that an activity can be delayed without affecting overall project duration
Formula: Activity Total Float = Activity LST –Activity EST
Activities with total float 0 cannot be delayed without delaying the whole project
Activities with some total float give some leeway in rescheduling them without delaying the whole project
However, when we use up the total float on an activity, it may cause later activities to be delayed and this will reduce their total floats

16. Components of Total Float
Free float:
Part of total float whose usage will not cause subsequent activites to be delayed and thus will not affect total float
Interfering float:
Part of total float whose usage will cause subsequent activities to be delayed and thus will affect their total floats

17. Free Float
The delay activity without affecting the total float of subsequent activities
Formula:
Free Float = min. EST of Activity’s successors – Activity EFT
J,4
TF= FF=3
Free Float= min(23 and 24) -20 20
G,1
G,1

18. Use of Activity Float
I ffor certain reasons you were force to delay some activities in a project, you would first choose to delay activities with free float. Once you have run out of such activities, you would then delay activities with interfering float.
In delaying such activites you would have to recompute the total float of all subsequent activities as they may have disappeared
Choose to delay activities without any total float only as a last resort as doing so would cause the project to be delayed

19. Project Duration and Critical Path
The shortest possible project duration is equal to the EST of the END activity
The critical path is the path comprising all activities with zero total float. Delays in any of the activities in the critical path will result in delaying the entire project. We can identify the critical path by looking for all activities with zero total float
The critical path is also always the longest continuous path activities in a network diagram from the beginning to the end of a project. The duration of the critical path is always equal to the shortest possible project duration
It is usual to label the critical path by coloring, highlighting it or by drawing two small strokes across all activities in the critical path

20. “End of Date”: Day 0 means “End of Day 0”
Timing Convention
“End of Date”: Day 0 means “End of Day 0”
“Start of Date”: Day 1 means “Start of Day 1”
If use “Start of Date” for start dates and “End of Date” for finish dates, and activity starting on Day 1 and ending on Day 2 has a duration of 2 (and not 1) days

21. Activity Scheduling A Activity Duration EST EFT LST LFT Total Float
Free Float A

22. Network diagram
Figure Dependency network with activity durations

23. Gantt Chart Schedule (Bar chart)
EST
Duration
Figure Schedule for two-person team showing parallel activities

24. Bar chart with milestones added
Figure Bar chart showing project milestones

25. Bar chart with ‘overhead’ task added
Figure Bar chart showing project management as continuous activity over project

26. Bar chart and resource histogram
Figure Bar chart with resource histogram

27. The project and other plans

28. PRINCE2® plans
Figure PRINCE2® plans

29. Contents of PRINCE2® project/stage plan
Figure Contents of PRINCE2® project and stage plans

30. Project budget
Figure Example budget for an IT project