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What is Critical Chain?

written by: Ronda Bowen • edited by: Michele McDonough • updated: 7/6/2011

This article, from the beginner's standpoint, looks at the term "Critical Chain."

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    Critical Chain is a project management method intended to speed up the process, and improve the rate of meeting due dates. The principle of the critical chain is a sequence requiring precedence and resource-dependent tasks mapped. These factors assist the team in estimating potential places where production may slow down. For more information on Critical Chain benefits take a look at Misty Faucheux’s article and at this DRM Associates Article.

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    How does Critical Chain work?

    The first step in critical chain is to determine the dependencies. There are two types of dependencies in a critical chain. The first dependency is a hand-off dependency. A hand-off dependency is something where the first task must be complete in order to provide the second task with required material. For example, one must perform research and have the research before writing a journal article. The second dependency type is resource dependency. This is where there is a delay of a task until a given resource finishes work on another task. For example, Jane needs to write code for the program, but right now, she is drowning in preliminary research and experimentation on another project. Jane cannot move on to the new task until this other task has been finished.

    Once dependencies have been determined, then buffers must be inserted. Buffers are time “padding" in order to ensure the success of a project. There are several different kinds of buffers:

    · The Project Buffer inserts at the end of the project to allow for the possibility that the project will take longer than scheduled.

    · Feeding Buffers take into account the potential for lost time within the chain. For example, if the research takes a week longer than planned, and no buffer has been inserted, then the whole team is now behind. If, on the other hand, there is a buffer, then this possibility has accounted for.

    · Resource Buffers take into account that some resources are dependent upon others to do their leg of the work. For example, Jim might be waiting for Jane’s part of the program so that he can check it for bugs. He cannot start, until Jane has finished the code and handed it off to him. These buffers ensure that tasks will be delivered on time.

    Once these buffers have been placed, careful buffer management ensures that the project stays on schedule. Buffer management involves checking in daily to adjust the time required to complete tasks.

    Multi-tasking is discouraged with this method of project management. What happens when utilizing critical chain methods is that task predecessors are delayed, creating a longer wait-time for completion of the dependencies. From this point of view, multi-tasking slows the team down.

    Critical Chain speeds the process of getting things done up. It allows more predictability and productivity in your project team.