Confusing Terms

Concepts and Terms to be known for the Exam

Topic covered:
• Change Control vs Configuration Control
• Critical Path Method vs Critical Chain Method

Change Control vs Configuration Control

Perform integrated change control process main purpose is to control changes on the project. To prevent scope creep and missed requirements. Well defined Change management involves Change Control and Configuration Control. Both terms are unique have specific meaning.

Change Control: In project management, change control is the process to identify, document, approve/reject and communicate changes to the baselines of the project (e.g.: scope, schedule and cost)
• The exact steps of change control are specified in the Change Management Plan by using the Change Control System.
• Changes need to be proposed in written format as Change Requests which will be analyzed and approved/rejected by Change Control Board (CCB).
• Change Control ensures all changes to the project are authorized which prevents scope creep and gold plating.

Configuration Control: Configuration control is about managing the specifications of the deliverables and processes with appropriate documentation throughout the lifecycle of the project from the very beginning to the closure of the project.
• The project configuration provides the information of the latest version of all the approved product and related documents/components and an archive of all previous versions.
• All the items under Configuration Control are known as Configuration Items (CI).
• Configuration Control is facilitated by the Configuration Control System.
• The exact details of Configuration Management are documented in the Configuration Management Plan, which is a subsidiary plan of the Project Management Plan.
• Configuration Management activities usually include: configuration identification / configuration status accounting / configuration verification / audit to ensure the latest configuration is adopted and delivered

The PMIS (Project Management Information System) is a tool that facilitates both the Configuration Control System as well as the Change Control System.

Both processes aim to protect the project from:
Change Control: protecting the project from undocumented changes to the project baselines by additional/changing requirements, etc.
Configuration Control: managing the specifications/versions of the deliverables, processes and related documents throughout the lifecycle of the project.


Both terms are part of Plan Human Resources Management process. Both RACI and RAM are tools used to ensure each project activities have responsible individual of the project team assigned for each activity.

RACI: RACI is a form of RAM (Responsibility Assignment Matrix) that defines project individuals / stakeholders as responsible, accountable, consult and inform statuses for different project activities
• Responsible — those who actually carry out the work to achieve the task objectives.
• Accountable — the one individual who is ultimately accountable for the success of a task and will approve the work created by those Responsible. There is ONE and ONLY ONE Accountable for a specific task / deliverable.
• Consulted — those who would have opinions that need to be considered / take into account / weighted in for the task / deliverable and be kept updated of the progress
• Informed — those who would need to be updated on the task progress

“Best Practice”: in the project, a role may be performed by many individuals while a person can perform many roles. However, for each task / activity, it is advisable to have a person assigned to one role only.

RAM: it stands for Responsibility Assignment Matrix; it is a grid-like responsibility assignment chart that shows assignment of project resources to individual work package.
. RAM clarifies the roles and responsibilities of project resources
. RAMs can have different levels, the higher levels for programs / project phases while the lower levels for project activities
. RACI Matrix and Linear Responsibility Chart (LRC) are two popular examples. The PMBOK® Guide describes RACI in more details as a type of RAM.
. Project managers are advised to involve team members when creating the RAM / RACI Chart.

Critical Path Method vs Critical Chain Method

In Project Schedule Management, the most important scheduling methods mentioned in the PMBOK® Guide are Critical Path Method and Critical Chain Method.

Critical Path Method (CPM): the most popular scheduling method in the Exam which involves the calculation of early start (ES), early finish (EF), late start (LS) and late finish (LF) through forward and backward passes in the project schedule network diagram. This will facilitate the project manager to estimate the floats (buffers) or the lack of for individual activities on the schedule network path.
• The Critical Path Method focuses on the sequence of activities/tasks to allow the project team to visualize the overall flow of the tasks.

Critical Chain Method (CCM): it builds on the Critical Path Method by considering the resource availabilities and their dependencies along all the task chain and adding buffers to the end of the chain, in order to protect the project schedule from slipping. This may result in a new Critical Path to be identified instead of the one found in Critical Path Method.
• The Critical Chain Method is derived from the “Theory of Constraints”, it focuses on resource availability and dealing with uncertainties/changes.
• It focuses on managing the overall buffer of all the activities on the chain. This will allow the project schedule to be in better control (instead of micro-managing individual schedule activities).
• If used correctly, the CCM will achieve higher efficiency by removing implicit buffers of individual tasks and lower schedule risks.
• There are 3 types of buffers:
o Project Buffer: placed at the end of the project, the project buffer provides contingency for the critical chain activities
o Feeding Buffer: placed at the end of non-critical chains in order to match the duration of critical chain
o Resource Buffer: placed on the critical chain to allow rooms for the designated resources to work on the critical chain tasks

• The Critical Path Method allows the project team to easily visualize the sequence of tasks and the estimated duration of individual tasks in a straight-forward manner. However, since there are no overall buffers to be added to the critical path, project team members may, while estimating for the duration of individual tasks, try to add “implicit buffers” to each task with a view to protect the overall schedule. This may result in “too much” buffers added to the critical path and make the estimation not efficient. The project manager needs to monitor closely the progress of individual tasks as one task progresses at a slower than expected will affect the whole project schedule.

• The Critical Chain Method just put the tasks together in a chain by considering the minimal time needed for individual tasks. An overall “project buffer” is added to the end of the chain which provides some protection against the project schedule. This may result in higher efficiency of the buffer estimation by combining the individual implicit buffer for an explicit buffer. Project team members would be able to provide a more aggressive schedule for each task as there is an overall buffer to protect the project schedule. The project manager will focus on managing the overall buffer during the executing and monitoring processes.

How to identify whether the Exam question is asking about Critical Path Method or Critical Chain Method?

The easiest way is to look carefully for the terms used:

• Terms used in Critical Path Method: Forward Pass, Backward Pass, Early Start, Late Start, Early Finish, Late Finish, Slack / Float, Total Slack / Float, Calculate the Duration, Critical Path
• Terms used in Critical Chain Method: Project Buffer, Feeding Buffer, Resources Buffer, Critical Chain, Resource constraints

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