1. A Novel by Eliyahu Goldratt
Critical Chain
A Novel by Eliyahu Goldratt

2. Product lifetimes are diminishing fast
Projects to create new products must be shortened drastically
Consider Modems, cellular telephones, VCR’s, PC’s,

3. Frequently projects go awry
Budget overruns
Time (schedule) overruns
Compromising functionality or content

4. Questions What is student syndrome? What is multitasking?
What is safety?

5. More Questions What about measurements?
What about early start vs. late start?
Of how much value is a project status report?
What about project planning tools like MS project?
What are some of Goldratt’s recommendations?

6. Task Duration Probability -- a Beta distribution
Actual Task
Estimated Time
Safety

7. Everybody overestimates the time required to do their task
According to Goldratt
This is called SAFETY
Does anybody want to talk about how much safety they put into their estimates?
Is this true in software development?
It is if you have an expert doing the estimating, who really knows how long it will take him

8. What happens after that--a possible scenario
The team leader adds safety time to the task to cover his responsibilities
The project leader adds more safety time
The project manager may add still more safety time

9. Conclusion>>>
Most of the time we have built into our projects is …..
Safety

10. Safety
Safety is however much time is added on to a task beyond its mean time of completion

11. What about IT Types
IT Types tend to underestimate the time it takes them to do tasks, because
They have never done the task before
They tend to be intuitive/thinkers—MEANING THEY ARE OPTIMISTS
They have not been told to take their estimates and double them
Especially when the task is new to them
IT developer productivities vary by as much as 10 to 1

12. Probabilistic task durations
Late durations tend to accumulate and may increase the length of the project
Early durations do not show up
Recall Parkinson’s Law and all the reasons for it
This explains why safety disappears

13. More Measurements -5 A -5 B E -5 C
+15 D

14. Other problems with safety
Is wasted by the “student syndrome”
Basically, this is procrastination
Is wasted by multitasking (a person who works on several tasks at the same time)
With each change of task, a set up is required
Is wasted by dependencies between steps
These dependencies cause delays to accumulate, but advances are wasted
Delays get passed on; advances don’t

15. Problems other than safety
Early start vs. late start
Existing measurements are not very useful because they are based on a cost world mentality
Goldratt does not like EV, PV, AC, BCWP, BCWS, ACWP, CV, SV, CPI, SPI, BAC, EAC, etc.

16. Multitasking Task A Task B Task C Task D A B C D A B C D A B C D A B C
A finishes A B C D A B C D A B C D A B C D
A finishes

17. Early Start vs. Late StartB 5 A 5 E 10 D 10 C 10

18. How much Safety is there likely to be?
Will project professionals admit how much safety they are putting into their estimates?
These professionals want to be 100% sure of getting finished on time
Therefore, the durations are likely to be twice as long as they should be
So CUT THEM IN HALF

19. Solutions
Take the safety out of the individual tasks and put it at the end of the critical path in the time buffer, called a project buffer
This means making the tasks roughly 50-60% as long as they would otherwise be.

20. Solution
Task A
Task B
Task C
Task D A B C D
Project Buffer

21. More solutions
At the point where each feeding path intersects with the critical path, place another time buffer, called a feeding buffer. The feeding buffer protects the critical path from delays occurring in the corresponding non-critical (feeding) paths.
You can now use a late start on all non-critical tasks, which Goldratt favors

22. Duration of Critical Path: 44 weeks
B/16
E/6
A/8
C/8
G/6
F/14
D/6

23. Goldratt: Put Safety in a Project Buffer at the end

24. B/8
E/3
FB/2
A/4
C/4
G/3
PB/22
FB/2
F/7
FB/2.5
D/3

25. B/8
E/3
FB/2
A/4
C/4
G/3
PB/22
FB/2
F/7
FB/2.5
D/3

26. A Different Network
B/8
E/3
FB/4
A/4
C/4
G/2
PB/22
FB/2
F/6
FB/2.5
D/3

27. More solutions
When resources are needed on the critical path, these resources are advised ahead of time (3 days??) exactly when they must make themselves available, through use of RESOURCE FLAGS. When that time comes, they must drop everything else and do the required critical tasks—no multitasking or student syndrome.

28. This is …..
Focus

29. The project manager must stay focused
Or the project will not be finished on time, within budget
This means applying the Pareto principle
80% of the benefit comes from 20% of the activities
By the time progress reports indicate something is wrong, its usually too late
Progress reports tell you that 90% of the project is finished in 90% of the required time.
However, another equal period of time is required to complete the remaining “10%,” in many cases

30. It is hard to stay focused when:
There are too many project paths on-going, in parallel
There are many critical or near critical paths

31. Figure 6-11. Example of Critical Chain Scheduling

32. Measurements are a major problem with projects
Measurements should induce the parts to do what is good for the system as a whole
Measurements should direct managers to the point that needs their attention
So often it occurs that we measure the wrong thing.
The wrong measure leads to wrong behavior
Tell me how you measure me and I will show you how I behave

33. More Measurements -5 -5 -5
+15

34. Measurements Goldratt likes UNUSED BUFFER DAYS as a measure
Goldratt does not like:
Lines of code created per hour
EV, PV, AC, BCWP, BCWS, ACWP, CV, SV, CI, SI
BAC (Budget at Completion), EAC (Estimated cost at completion)

35. Projects are like chains
Each task in sequence is a link in a chain
Each link has two things
weight, to which cost is analogous
strength, to which throughput is analogous

36. Cost vs Throughput
Goldratt maintains that management in the cost world is a mirage
efficiency becomes paramount
local improvements are necessary to get global ones
Goldratt suggests the managers should manage in the throughput world, a totally different paradigm
must find the constraint--the weakest link
concentrate on that
By the way, what is the ultimate constraint???

37. Remember the five steps of TOC
IDENTIFY the project constraint--the critical path
Decide how to EXPLOIT that constraint
SUBORDINATE everything to that decision
ELEVATE the systems’ constraint
Go back to step 1, and find another constraint

38. Which is not one of the five steps in the TOC?
IDENTIFY the project constraint--the critical path
Decide how to EXPLOIT that constraint
SUBORDINATE that decision to everything else
ELEVATE the systems’ constraint
Go back to step 1, and find another constraint

39. Conflicts Based on faulty assumptions
Use evaporating cloud to surface the assumptions
Then question every one of them
A bad assumption leads to a breakthrough solution or injection
When resources are needed on the critical path, these resources are advised ahead of time exactly when they must make themselves available. When that time comes, they must drop everything else and do the required critical tasks.

40. Measurement solutions
Measure progress only on the critical path; what percent of the critical path we have already completed. This is all we care about!!
Have a project leader measure progress on a non critical path in terms of unused buffer days

41. Shrinking the task time: Effects
There is less procrastination
There is much more focus
There is less multitasking

42. More Suggestions Put your “BEST” people on the critical path
Watch out for critical chains

43. What are the ramifications of a delayed software product, intended for commercial sale?
Less market share
Less profit; maybe no profit
Lower analyst profit expectations
Declining share price
Out of business?
How many firms has Microsoft driven out of business?
Ask the Borland founder what the implications of getting a product late to the marketplace are

44. What about Procurement
Most firms enter into LOSE/LOSE Strategies
A fixed-price lowest bidder contract is LOSE/LOSE Strategy
This forces Contractors to under bid their costs, hoping to make it back on the changes to the requirements that the customer will have to pay for
Instead, Contractors should be induced to deliver product on time, with as much functionality as possible
How would you do this?

45. What happened to Professor Silver?

46. Shrinking task time—upon further review???
Not recommended for creative activity
Some studies show that the added duress causes more frustration
More mistakes, more rework, more fixes
Source: “Deadline,” by Tom Demarco

47. Time Batching--Another Time Waster
Analysis paralysis
Approval cycles
Formal document release
Regularly scheduled meetings
Planning cycles
Work queues

48. Fast Tracking and Reduced Time Batching

49. Fast Tracking and Reduced Time Batching

50. That’s all, Folks