Section: Volume B
Explanation:
6.6.2.3 Critical Chain Method
The critical chain method (CCM) is a schedule method that allows the project team to place buffers on any project schedule path to account for limited resources and project uncertainties. It is developed from the critical path method approach and considers the effects of resource allocation, resource optimization, resource leveling, and activity duration uncertainty on the critical path determined using the critical path method. To do so, the critical chain method introduces the concept of buffers and buffer management. The critical chain method uses activities with durations that do not include safety margins, logical relationships, and resource availability with statistically determined buffers composed of the aggregated safety margins of activities at specified points on the project schedule path to account for limited resources and project uncertainties. The resource-constrained critical path is known as the critical chain.
The critical chain method adds duration buffers that are non-work schedule activities to manage uncertainty.
One buffer, placed at the end of the critical chain, as shown in Figure 6-19, is known as the project buffer and protects the target finish date from slippage along the critical chain. Additional buffers, known as feeding buffers, are placed at each point where a chain of dependent activities that are not on the critical chain feeds into the critical chain. Feeding buffers thus protect the critical chain from slippage along the feeding chains.
The size of each buffer should account for the uncertainty in the duration of the chain of dependent activities leading up to that buffer. Once the buffer schedule activities are determined, the planned activities are scheduled to their latest possible planned start and finish dates. Consequently, instead of managing the total float of network paths, the critical chain method focuses on managing the remaining buffer durations against the remaining durations of chains of activities.

Figure 6-19. Example of Critical Chain Method

Explanation/Reference:
Explanation:
7.2.1.6 Enterprise Environmental Factors
Described in Section 2.1.5. The enterprise environmental factors that influence the Estimate Costs process include, but are not limited to:
Market conditions. These conditions describe what products, services, and results are available in the

market, from whom, and under what terms and conditions. Regional and/or global supply and demand conditions greatly influence resource costs.
Published commercial information. Resource cost rate information is often available from commercial

databases that track skills and human resource costs, and provide standard costs for material and equipment. Published seller price lists are another source of information.
Process: 7.2 Estimate Costs
Definition: The process of developing an approximation of the monetary resources needed to complete project activities.
Key Benefit: The key benefit of this process is that it determines the amount of cost required to complete project work.
Inputs
1. Cost management plan
2. Human resource management plan
3. Scope baseline
4. Project schedule
5. Risk register
6. Enterprise environmental factors
7. Organizational process assets
Tools & Techniques
1. Expert judgment
2. Analogous estimating
3. Parametric estimating
4. Bottom-up estimating
5. Three-point estimating
6. Reserve analysis
7. Cost of quality
8. Project management software
9. Vendor bid analysis
10.Group decision-making techniques
Outputs
1. Activity cost estimates
2. Basis of estimates
3. Project documents updates

Section: Volume E