critical chain
DESCRIPTION
critical chainTRANSCRIPT
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Practical Critical Chain Scheduling
Primavera User ConferenceDecember, 2000
Rob NewboldProChain Solutions Inc.
(703) 490-8821 www.prochain.com
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
1. Introduction
BackgroundAgenda
Critical Chain Scheduling (Readers Digest) Practical Recommendations
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Practical Methodology
When managing projects in a business context, methodology is how we do what we do to ensure high quality, repeatable results.1
The question isnt how we schedule projects, its how we solve business problems.
Practical business solutions must integrate tools, procedures and rules.
* The M-Word Explored, Tony Nish, PM Network, September 1999, p. 67.
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
2. Critical Chain Scheduling
Single Project SchedulingMultiple Project Scheduling
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Step 1: Create the Project Network
5:Design 2:Dev
2:Dsn 3:Proto 4:Dev 2:Tst
Must be reasonableChallenge all assumptions, such as
resources, dependencies, durations Ideally, use average touch time for task
durations: no allowance for uncertainty
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Estimating Task Times
3 wks
50%
6 wks
90+%
Add an allowance for uncertainty
10 wks Add an allowance for other projects
These are the estimates that usually go into our project schedules
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
5:Design
2:Tst
Step 2: Identify The Critical Chain
B.) Then identify the Critical Chain
The Critical ChainThe longest path through the network considering
both task and resource dependencies
A.) First, eliminate resource contention
2:Dsn 3:Proto 4:Dev
2:Dev
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Focused Cycle Time Reduction
Iterate until the Critical Chain is acceptable in length and content
Identify the Critical Chain
Challenge the assumptions alongthe Critical Chain
Change thenetwork to reflect new assumptions
Levelthe
Load
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Step 3: Deal with Uncertainty
2 Dev
2:Dsn 3:Proto 4: Dev 2:Tst 6.5: Project Buffer
5:Design 2 Dev
2:Dsn 3:Proto 4: Dev 2:Tst
5:Design
Feeding Buffer
The Project Buffer protects the project due date from disruptions along the Critical Chain.
6.5: Project Buffer
Feeding buffers protect the Critical Chain from disruptions in non-Critical Chain tasks.
2: FB
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Shorter Project
The Difference
10:Design 4:Dev
4:Tst4:Design 6:Proto 8:Dev
2 Dev
2:Dsn 3:Proto 4: Dev 2:Tst 6.5: Project Buffer
2: FB5:Design
Better Protected
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
2 Dev
2:Dsn 3:Proto 4: Dev 2:Tst 6.5: Project Buffer
2: FB5:Design
Today
Design: We completed the 2-day task, but we still have 4 days to go on our other task
Projected task times
Buffer consumptionProjected task time
Proto: We havent had a chance to get to our task"
Project ReportCC Complete: 15%PB Consumed: 30%
Updating Tasks
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Multi-Project Scheduling
2 Dev
2:Dsn 3:Proto 4: Dev 2:Tst 6.5: Project Buffer
2: FB5:Design
1
2
1. Set projects at their due dates
3. Collect drum resource tasks5. Reschedule projects
DrumSchedule 2 Dev4: Dev 2 Dev4: Dev
2: FB5:Design 2 Dev
2:Dsn 3:Proto 4: Dev 2:Tst 6.5: Project Buffer
4. Resolve drum contention
6. Make necessary adjustments2. Select the drum resource(s)
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
3. Practical Recommendations
Strive for Task EngagementManage BuffersDevelop Repeatable ProcessesGate Your Projects
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Task ATask BTask C
Tasks assigned to a resource
3 days3 days3 days
Should happen: Task A Task B Task C3 days 3 days 3 days
Problem: Multitasking
Does happen:
8 days
A CB CA B CA B CA
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Problem: Interruptions
Phone callsConversation in the next cubicleEmailA knock on the door . . .
Minimize interruptions on key tasks!
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Recommendation:Strive for Task Engagement
Minimize multitasking with clear, stable priorities
Find ways to minimize interruptions Identify key tasksPromote complementary work rules
Task Engagement: the need to focus on a task and work it to completion before being interrupted for other activities.
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Recommendation: Manage Buffers
Use average but credible task durationsUse up to 50% buffer sizingCreate project buffers as explicit tasksTrack buffer consumptionReport based on buffer status
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Project % Complete
Project
Buffer % Used
Project Due Date
CompleteProject Early Finish
Planning Threshold
Action Threshold
Executive Decision Support
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Recommendation:Develop Repeatable Processes
Scheduling processes Credibility Risk management Buffer management
Tracking and reporting processes Buffer analysis and reports Clear, stable task priorities Cost analysis if appropriate
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Copyright 2000 by ProChain Solutions, Inc.http:/ /www.prochain.com
Recommendation: Gate Your Projects
Project charterPhase/gate processesTake into account capacity (drum resource)Maintain credibility
Typically, the company has in process twice as much work as it can staff effectively. This means that half the work is sitting idle somewhere, and each project takes twice as long as it needs to.
Preston Smith, Saying No to Customers, Across the Board, March 1994