A Novel by Eliyahu Goldratt Critical Chain A Novel by Eliyahu Goldratt

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

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

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

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?

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

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

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

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

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

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

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

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

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

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.

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

Early Start vs. Late Start B 5 A 5 E 10 D 10 C 10

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

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.

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

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

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

Goldratt: Put Safety in a Project Buffer at the end

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

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

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

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.

This is ….. Focus

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

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

Figure 6-11. Example of Critical Chain Scheduling

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

More Measurements -5 -5 -5 +15

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)

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

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???

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

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

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.

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

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

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

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

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?

What happened to Professor Silver?

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

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

Fast Tracking and Reduced Time Batching

Fast Tracking and Reduced Time Batching

That’s all, Folks