What Is Critical Chain Project Management?

Critical Chain is a project management method based on Theory of Constraints proposed by Dr. Eli Goldratt.

Critical chain project management is based on methods and algorithms derived from constraint theory. The concept of CCPM was introduced in 1997 by Eliyahu M. Goldratt's book "The Key Chain". The application of CCPM is considered to achieve 10% to 50% of projects faster and / or cheaper than traditional methods developed in the 1910s to 1950s (ie CPM, PERT, Gantt, etc.).

According to a study by the Standish Group and other companies of traditional project management methods as of 1998, only 44% of projects are usually completed on time. Projects are usually completed at 222% of the original plan, 189% of the original budgeted cost, 70% of the projects fall short of the planned scope (delivered technical content), and 30% are cancelled before completion. CCPM attempts to improve performance relative to these traditional statistics.

Using traditional project management methods, 30% of the time and resources lost are usually consumed by wasted technologies such as poor multitasking (especially task switching), student syndrome, Parkinson's law, built-in delays, and lack of priority.

In a project plan, key chains are a sequence of priorities and resource-related tasks that prevent a project from completing in a shorter period of time, given limited resources. If resources are always available in an unlimited number, the critical chain of a project is the same as its critical path approach.

Critical chains are an alternative to critical path analysis. The main characteristics that distinguish critical chains from critical paths are:

1. Use (usually implicit) resource dependencies. Implied means they are not included in the project network, but must be identified by looking at the resource requirements.

2. Lack of search for the best solution-a "good enough" solution is sufficient because:

a. It is known that there is no analytical method for finding the absolute best value (ie, having the overall shortest critical chain).

b. The inherent uncertainty of the estimate is much greater than the difference between the best and near-optimal ("good enough" solution).

3. Identify and insert the buffer:

a. Project buffer

b. connection buffer

c. Resource buffering (companies are generally reluctant to provide more resources)

4. Monitor project progress and health by monitoring the buffer's consumption rate rather than the performance of the planned single task.

CCPM plans to roll up a lot of safety time added to the tasks in the project into a buffer-to protect the performance of due dates and avoid wasting these through the integration of poor multitasking, student syndrome, Parkinson's law and low synchronization Safety time.

Critical chain project management uses buffer management instead of earned value management to evaluate project performance. Some project managers believe that earned value management technology is misleading because it does not distinguish between the progress of project constraints (ie critical chains) and the progress of non-constraints (ie other paths). The event chain method determines the size of the project, feed, and resource buffers.

Why consider human factors and work habits

All project work is performed by people. If human factors are not considered, the goal will be difficult to achieve. In other words

The proposal of the key chain method is mainly based on two considerations:

(1) If a job starts early, there is often a certain amount of slack, time fluctuations, and safety margins, then the job is often delayed until the day it is finally allowed. The entire work during this period did not give full play to its efficiency, resulting in a waste of manpower and material resources. If the arrangements are made according to the latest time, there is no floating and safety margin, and the pressure on the staff working on this project is virtually imposed. He has no choice but to work as hard as possible to complete the scheduled tasks on time. This is an idea adopted by the key chain method.

(2) When project estimates are made, some hidden margins in individual estimates need to be eliminated.

Can improve project performance

In order to ensure that the project can be completed, we also need to arrange a margin in the work, that is, to tap the potential in the estimation. For example, if each work is reduced by 50%, the surplus time will be arranged according to 50% of the project duration. The work margin will still be started at the latest of the project. According to the time required for the completion of the project, the last one of the project will be arranged first. Work, and then determine the next work, long-term work, and finally arrange the initial work of the project. The entire work arrangement is reversed, and the project is arranged forward from the end of the project. Arrange safety margins at the end of the project's construction period.

Use the reverse method to sort. If the previous work has delayed the resources, the delay in time will be reflected in the final time margin. For example, the first stage of development is estimated to take 10 weeks, actually 15 weeks, and an increase of 5 weeks. These 5 weeks are actually the delay time, which is exactly the time allowed in the reserve.

Easy to focus on in project management

The second benefit is to seize the key points in project management and manage key tasks, instead of needing to be as comprehensive as traditional project management. It is necessary to regularly record the progress of work, analyze deviations and track the progress of the project for each task. . The key chain method only needs to pay attention to those projects and work that have been postponed. If the work is performed within the normal range, it can be placed in a slightly less important position in management work. At the same time, the overall management and control of the project's standby management and the overall progress of the project. This is a basic principle of the key chain method.

Complete the project ahead of time

One of the benefits of critical chain management is the completion of projects in advance. It is usually at least 1/3 ahead of the critical path method.

As the example just mentioned, if it is managed according to the critical path method, it may take 45 weeks. If two tasks are considered to be increased, for example, the development is postponed for 5 weeks, and the copywriting work is postponed for 5 weeks. At this time, the total project can be Completed within 35 weeks.

The main idea of the key chain method is how to consider people's work habits in management work, and adopt a new method to improve project performance in project estimation and project management according to local conditions.