9/26/2016
Presenter Intro: Al Rusnak, PMP
Sr. Principal Program Manager, Cadence
Specializing in:
–
–
–
–
Scheduling for Mega Programs
Risk Analysis
Semiconductor Program Management
Customer Program Management
Degrees:
– BS, Electrical Engineering
– MS, Electrical Engineering
Email: [email protected]
Tel:
408 914 6086
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Random Event-Driven Schedule Risk
Al Rusnak, PMP
PMISV - 2016 Annual Symposium,
Managing Uncertainty in Modern Projects: Risks in Your Project Are Closer than They Appear
Santa Clara Convention Center, Santa Clara, CA
October 3-4, 2016
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9/26/2016
Random Event-Driven Schedule Risk
Overview
• Problem definition
• Random arrival rate risk characteristics
• Identification of random arrival rate risks
• Statistical nature of random arrival risks
• Modeling and defining the impact
• Summary
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Problem Definition
Common project attributes:
−
−
−
−
Use the very latest technologies
Concurrent technical development
Careful and detailed planning
Some risks were not taken into account
Impact:
− Risks occurred as expected
− Plan was well beyond initial projections
− Resources issues
− Multi-tasking
− Working extended hours
− Resource allocation issues
− Delayed/lost business opportunities
Practice:
−
−
−
−
−
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Risks were known to exist
Projections would not be accepted
Beyond the control of the project
Re-adjust plan when changes occur
No method to provide an estimate
PMO-oriented questions:
− Initial approval if impacts modeled?
− Real ROI of the project?
© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
New Category of Risks
Current modeling methods
− Normally internal events
− Other events within the project
− Modeled as a single risk event
− Impact one or more tasks
− Random timing
Examples:
− Extended task durations
− Risk from one task related to another
task
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Random event modeling method
− Normally external events
− Independent of the project
− Risk must be modeled as having
− Multiple occurrences
− Random inter-arrival rate
Examples:
− Customer/marketing requests
− Technology updates
© 2016 Cadence Design Systems, Inc. All rights reserved..
Project and PMO Objectives
Project objectives:
• Schedule implications beyond normal schedule risk analysis
• Identify potentially unstable projects
• Define acceptable change rates before the project starts
PMO objectives:
• Before project approval:
– Impact to schedule
– Impact to ROI
– Impact to other projects
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Risks with Random Arrival Rate Characteristics
Random arrival rate risk case studies
Case study 1 - Change requests
• New change requests identified at every weekly meeting
• Usually multiple change requests
• 5 change requests were received in one meeting
Case study 2 –Technology and customer requirement updates for the newest
technologies
•
•
•
•
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Concurrent development
Multiple customer requirements updates
Multiple technology updates
Not modeled at the beginning of the project
© 2016 Cadence Design Systems, Inc. All rights reserved..
Identification of Random Arrival Rate Risks
• Any risk that may occur more than just one time
• Semiconductor technology
– Marketing/customer requirements changes
– Technology updates
• Other areas
– Weather (construction industry)
– Permits, inspections, and corrections
– Legal regulations changes
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Statistical Nature of Random Arrival Risks
• Random arrival event risk
– A risk
– Multiple occurrences
– Randomly distributed over time
• Random arrival rate
– Poisson process
– Constant arrival rate (random inter-arrival times)
– Exponential density distribution
• Examples of random arrival rate parameters
λ
T
4 / month
.25 month
.25 / month
4 months
Risk
Requirement changes
Technology updates
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Modeling and Defining the Impact
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Case Study 1 – Single Risk
Define risks
• Weekly change orders are submitted
λ
T
1 events / 5 days = 0.2
5 days/event
Random Risk Event
Customer requirements
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Impact Definition
“Requirements change” impact table
Task
Impact
Requirements
Architecture
0 days
0 days
Design, RTL Coding
5 days
Verification
Physical Design
Initial Implementation
Stable Implementation
Final Implementation
12
0 days
Normally not a valid assumption
0 days
10 days
Restart
© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Simulate
Task
Design, RTL Coding
Stable Implementation
Final Implementation
Impact
5 days
10 days
Restart
Summarize
Conclusion: Unstable results!
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Case Study 2 – Multiple Risks
Define risks
• Requirement changes
• Technology updates
λ
T
Requirements
4 / qtr.
32 days / event
Technology updates
2 / qtr.
65 days / event
Risk
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Impact Definition (Impact Table)
Task
Customer Requirements
Technology Updates
Requirements
0 days
0 days
Architecture
0 days
0 days
Design, RTL Coding
5 days
0 days
Verification
0 days
0 days
Initial
0 days
0 days
Stable
10 days
10 days
Final
10 days
10 days
Physical Design (PD)
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Simulate
“Customer requirements” random inter-arrival time
Event Number
1
2
3
4
42
21
12
7
41
95
49
15
31
10
8
4
1
33
16
17
99
22
0
51
Iteration
1
2
3
4
5
6
7
8
9
10
16
19
9
4
60
34
49
16
41
13
37
51
17
10
7
15
52
1
55
267
176
“Technology
updates”
6
7
8
9
10 random
Event
Number45
71
45
4
54
27
1 7
224
33
5
2
18
1124
Iteration
34
19
69
81
30
164
2128
150
255
42
3 1 21 12 11
43
65
730
739
14
12
1 2 22 26 3
14
5 3 20 33 1
58
57
4233
153
77
3
4 4 107 26 75
72
14
8479
45
60
71
85 5 16 87 11
26
2
2286
20
102
11
2 6 20 80 26 16361
98
9
104
74
29
18 7 4 76116 33027
17
58
5
90
23
8
135
12
145
25
227
9
7
173
54
71
25
10
10
95
45
19
49
5
inter-arrival times
6
7
8
9
10
153
74
116
17
43
43
243
50
27
20
5
66
154
29
30
71
19
75
62
85
61
12
1
36
65
275
11
63
39
21
32
128
196
140
4
109
43
8
172
81
24
25
43
75
8
62
44
51
78
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Random Event Schedule
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Simulate
Task
Customer
Requirements
Technology
Updates
Event
Date
R1
01/14/16
Requirements
Design, RTL Coding
5 days
0 days
P1
02/29/16
RTL Stable, Initial chip implementation
0+0
PD, Stable
10 days
10 days
R2
04/14/16
RTL Final, Stable Implementation
5 + 10
18
Task(s)
Impact (days)
0
© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Simulate
Task
Customer
Requirements
Technology
Updates
Design, RTL Coding
5 days
0 days
PD, Stable
10 days
10 days
19
Date
01/14/16
02/29/16
04/14/16
Task(s)
Requirements
RTL Stable, Initial chip implementation
RTL Final, Stable Implementation
P2
04/21/16
RTL Final, Stable Implementation
Impact (days)
0
0+0
5 + 10
0 + 10
© 2016 Cadence Design Systems, Inc. All rights reserved..
Simulate
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Event
R1
P1
R2
Event
Date
Task(s)
Impact (days)
R1
01/14/16
Requirements
P1
02/29/16
RTL Stable, Initial chip implementation
0+0
R2
04/14/16
RTL Final, Stable Implementation
5 + 10
P2
04/21/16
RTL Final, Stable Implementation
0 + 10
0
© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Simulation Results – Iteration 1
Event
Date
Task(s)
R1
R2
R3
R4
R5
R6
01/14/16
04/14/16
07/06/16
09/27/16
10/11/16
11/04/16
Requirements
RTL Final, Stable Implementation
Final Implementation
Final Implementation
Final Implementation
Taped Out
Impact
(days)
0
5 + 10
10
10
10
none
P1
P2
P3
P4
P5
02/29/16
04/21/16
05/05/16
07/14/16
08/19/16
RTL Stable, Initial chip implementation
RTL Final, Stable Implementation
RTL Final, Stable Implementation
Final Implementation
Final Implementation
0+0
10
0 + 10
10
10
Generate new event table for iteration 2 and so on… and repeat simulation
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Simulation Results
Event
R1
P1
R2
P2
P3
R3
P4
P5
R4
R5
R6
Date
01/14/16
02/29/16
04/14/16
04/21/16
05/05/16
07/06/16
07/14/16
08/19/16
09/27/16
10/11/16
11/04/16
Task(s)
Requirements
RTL Stable, Initial chip implementation
RTL Final, Stable Implementation
RTL Final, Stable Implementation
RTL Final, Stable Implementation
Final Implementation
Final Implementation
Final Implementation
Final Implementation
Final Implementation
Taped Out
Impact (days)
0
0+0
5 + 10
0 + 10
0 + 10
10
10
10
10
10
none
Generate new event table for iteration 2 and so on… and repeat simulation
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Summarize
23
Iteration
0
Tapeout
06/24/16
Iteration
1
2
3
4
5
6
7
8
9
10
…
19
20
Tapeout
10/28/16
08/12/16
07/22/16
08/19/16
08/27/16
09/16/16
10/21/16
09/23/16
Unstable
07/15/16
…
09/16/16
08/26/16
Result: Stable schedule
© 2016 Cadence Design Systems, Inc. All rights reserved..
Generate Statistical Information
Tapeout Date
Original: 6/24/16
4
Post Analysis:
Mean: 9/19/16
Median: 9/16/16
Mode: 9/16/16
100%
90%
80%
3
70%
60%
2
50%
40%
30%
1
20%
10%
0
0%
Frequency
24
Cumulative %
Normal Cummulative Distribution fit
© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Generate Statistical Information
Tapeout Date
Original: 6/24/16
4
Post Analysis:
Mean: 9/19/16
Median: 9/16/16
Mode: 9/16/16
100%
90% Confidence: 20.7 weeks
90%
80%
3
70%
50% Confidence: 12.7 weeks
60%
2
50%
40%
30%
1
20%
10%
0
0%
Frequency
25
Cumulative %
Normal Cummulative Distribution fit
© 2016 Cadence Design Systems, Inc. All rights reserved..
Summary
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Case Study #1 – Change Requests
Lessons learned:
• High arrival rate can make the project unstable
• Modeled arrival rate and impact can help to identify
–
–
–
–
Project instability
Acceptable project predictions
Management understanding
Guidelines for execution during the project
– Define acceptable arrival rates
– Monitor the arrival rate
27
© 2016 Cadence Design Systems, Inc. All rights reserved..
Case Study 2 – Technology / Requirement Updates
Lessons learned:
• Arrival rate and impact—Significant adjustment to the schedule
• High arrival rate—Unstable project
• Large impact for the risk event—Unstable project
• Modeled arrival rate and impact can help to identify
–
–
–
–
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Instability
Acceptable project results
Improved management understanding
Guidelines for execution during the project
– Define acceptable arrival rates
– Monitor the arrival rate
© 2016 Cadence Design Systems, Inc. All rights reserved..
14
9/26/2016
Summary
• Risks that have random arrival rate characteristics
− Continually occur during the course of the project
− Have a random arrival rate
• Identification of random arrival rate risks
−
−
−
−
Any multiple occurring risk
Marketing/customer requirements
Technology updates
Weather
• Statistical nature of random arrival risks
− Poisson process
− Constant inter-arrival rate
− Exponential density distribution
29
© 2016 Cadence Design Systems, Inc. All rights reserved..
Summary
Model and define the impact:
1.
2.
3.
4.
5.
6.
Define the random risks
Define the inter-arrival rate
Define the impact table
Random number generation
Inter-arrival event schedule
Schedule estimation (simulation)
− For each “iteration”
− For each “risk event”
− Identify which task is impacted
− Adjust the schedule to reflect the impact
− Capture the finish date
− Summarize the finish dates and generate Cumulative Distribution chart
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Appendix A – Exponential Distributions
Exponential density distribution
Exponential cumulative distribution
Where λ is the inter-arrival rate
Source: Wikipedia, the free encyclopedia
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© 2016 Cadence Design Systems, Inc. All rights reserved..
Other Exponential Distribution Properties
Parameters
Support
PDF
CDF
Mean
Median
Mode
Variance
λ > 0 rate
x ∈ [0, ∞)
λ e−λx
1 − e−λx
λ−1 (=β)
λ−1 ln(2)
0
λ−2 (=β2)
Source: Wikipedia, the free encyclopedia
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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9/26/2016
Appendix B – Generating a Random Number
Spreadsheet calculation
=-(LN(RAND())) / $F$4
Where $F$4 is λ
Source: Wikipedia, the free encyclopedia
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© 2016 Cadence Design Systems, Inc. All rights reserved..
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