When several workstreams on a project come together into a single dependent activity, that dependent activity cannot start until all of the preceding workstreams have been completed. This means that if you have five workstreams all coming together for (for example) an end-to-end system test phase, then even if 4 of the 5 streams finished early, the testing will still start late if the fifth stream is delayed.

Dependencies

Given what we know of Student Syndrome and Parkinson’s law, adding contingency to tasks on a project simply results in the project delivering later. Often, contingency is mentally factored in by people working on the project, they will start fully applying later than normal when there is an understanding that contingency exists. This can end up with situations where adding contingency not only makes delivery later, but the contingency is actually over-run, and projects get even later. For this reason, CCPM usually requires specialist software to calculate and keep track of the time buffer.

Aggregating Contingency - Factoring in Considerations

Critical Chain Project Management is a project management methodology defined as a set of interlinked techniques and tools that work collaboratively to significantly improve the processes and operation of scheduling and execution in project, program, and portfolio environments.Eliyahu Goldratt developed CCPM. Goldratt had been working on improving factory efficiency and advocated identifying production bottlenecks and focusing on keeping production operating at maximum efficiency. Goldratt extended his work beyond factories and into project management, publishing ‘Critical Chain' in 1997.

Preamble

Tasks often take longer than the estimated time, but very rarely get delivered early. Goldratt cites three reasons for this: <ul><li>Student Syndrome</li><li>Dependencies</li><li>Parkinson’s Law</li></ul>

Key Problems that the CCPM Methodology Tackles

Attributed to C. Northcote Parkinson, Parkinson’s Law on the pursuit of progress states that work expands to fill the time available for its completion.

Parkinson’s Law

When using the CCPM, we avoid focusing on milestones for delivery. Instead, we focus on encouraging and rewarding behaviors that lead to the delivery of critical activities as fast as possible. This requires a change of reporting and a change in mindset. To avoid Parkinson’s law, we focus on delivering as fast as possible, rather than focus on milestone dates. Rather than getting updates in terms of percentage complete, we ask for estimates of ‘Remaining Duration’. Reporting in this way provides a more realistic picture of when activity is likely to complete and prevents late-emerging issues

Remaining Duration Reporting

CCPM is very clear on its views on multitasking. It advocates for strict discipline where no one working on a critical path activity should be working on anything else at the same time. Eliminating multitasking can have a significant impact on productivity.

CCPM on Multitasking

CCPM introduces a new type of chart to track projects, The Fever ChartThe fever chart plots the percentage of the Project Buffer that has been consumed against the percentage of the critical chain that has been completed. Progress is plotted as a line graph, giving a running commentary of how the project is performing. This can be applied in program and portfolio levels as well, as a diagnostic tool.

Fever Charts : Assessing Project Performance

This truism suggests that most people do not fully apply themselves to activities until at least half the time allocated has elapsed. This idea of planned procrastination has been backed by research and appears to be entirely normal behavior. But it does mean that any margin for error is removed, resulting in a tendency for work to be completed late, no matter how much time has been allocated.

Student Syndrome

Since the strength of a chain is determined by the weakest link, then the first step to improve an organisation must be to identify the weakest link.

The Critical Chain model introduces Feed Buffers for the noncritical chain. Feed buffers are not included in the overall Project Buffer but are used as a way of insulating the critical path of the project from non-critical workstream elements. By building in Feed Buffers, CCPM reduces the risk of projects overrunning due to dependencies.

Feed Buffers : Averting Dependencies

Dissecting the core of this business management novel : Critical Chain Project Management (CCPM) Methodology

This fast-paced business novel does for project management what The Goal and It's Not Luck have done for production and marketing. Goldratt's novels have traditionally slain sacred cows and delivered new ways of looking at processes which seem like common sense once you read them. Critical Chain is no exception. In perhaps Eli's most readable book yet, two of the established principles of project management, the engineering estimate and project milestones, are found wanting and dismissed, and other established principles are up for scrutiny - as Goldratt once more applies his Theory of Constraints. The approach is radical, yet clear, understandable and logical. New techniques are introduced, and Project Buffers, Feeding Buffers, Limit Multitasking, Improved Communications and Correct Measurements make them work. Goldratt even handles the complicated statistics of dispersed variability versus accumulated variability so deftly you won't even be aware of learning about them - they ll just seem like more common sense! Critical Chain is critical reading for anyone who deals with projects. If you use block diagrams, drawings or charts to keep track of your activities, you are managing a project - and this book is for you.

CCPM on Multitasking

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