ESD.36 System Project Management
+
-
Lecture 7
The Rework Cycle
Instructor(s)
Dr. James Lyneis
Copyright © 2012 James M Lyneis.
+
Today’s Agenda

Overview: Causes of Project Dynamics

The Rework Cycle

Integrating Tools in Project Planning

Simple Model of Project Dynamics, Pt. 1
2
+
-
Typical Behavior Modes on a Project
Project
Staffing
Productivity
(Normalised)
2
Typical
Plan
1
Typical
Plan
Time
Time
© 2001 John Wiley & Sons, Ltd. All rights reserved. This content is excluded from our
Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.
3
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Drivers of Project Dynamics


The “rework cycle”
Feedback effects




Negative, controlling
Positive, re-enforcing, often “vicious
circles”
Knock-on or domino effects within or
between work phases
Knock-on or domino effects between
projects
4
+
Today’s Agenda

Overview: Causes of Project Dynamics

The Rework Cycle

Integrating Tools in Project Planning

Simple Model of Project Dynamics, Pt. 1
5
Network Diagram for NMM Case
(from 2010 Homework #1)
+
-
i,
Diesel
Dev
c,
Diesel
Specs
d, Elec
Drive
Specs
a, Start
n,
Diesel
Delivery
j, Elec
Drive
Dev
b, Req
o,
Integra
tion
k,
Chassis
Design
e,
Layout
w,
Road
Test
m,
Internal
Fittings
y, Finish
t,
PowerVehicle
Integ
l, Body
Design
s, Body/
Chassis
Prototype
f,
Electronics
Design
p,
Electronics
Delivery
g, Soft
ware
Specs
r,
Charging
Assembly
U, Final
Assembly
v,
Dynamo
Lab Test
x, Car
Show
Setup
q,
Electronics
Software
Integ
h, Soft
ware
Dev
6
+
-
The Network View of a Program –
Task Accomplishment
Task Accomplishment – Task X
Productivity
Staff
Work Done
Work to Do
Work Being
Accomplished
7
+
Network Diagram for NMM Case
-
Productivity
Staff
Work Done
Work to Do
i,
Diesel
Dev
c,
Diesel
Specs
d, Elec
Drive
Specs
a, Start
o,
Integra
tion
k,
Chassis
Design
e,
Layout
r,
Charging
Assembly
w,
Road
Test
m,
Internal
Fittings
y, Finish
t,
PowerVehicle
Integ
l, Body
Design
s, Body/
Chassis
Prototype
f,
Electronics
Design
p,
Electronics
Delivery
g, Soft
ware
Specs
Two stocks and one flow
subsumed within each
task of network diagram
n,
Diesel
Delivery
j, Elec
Drive
Dev
b, Req
Work Being
Accomplished
U, Final
Assembly
v,
Dynamo
Lab Test
x, Car
Show
Setup
q,
Electronics
Software
Integ
h, Soft
ware
Dev
8
+
Aggregate Model of Network View
-
Productivity
Staff
Work Backlogs and Flow
Work to
Do
1,000 Tasks
100 Tasks/Month
Work to Do
+
+
Work Being
Accomplished
Work Done
Initial Work
to Do
500 Tasks
50 Tasks/Month
Work Being
Accomplished
0 Tasks
0 Tasks/Month
0
Initial Work to Do = 1000 tasks
Productivity = 1 task/mo/person
Staff = 40 people
Work Done
5
10
15
Work to Do : Traditional View
Work Done : Traditional View
Work Being Accomplished : Traditional View
20 25 30
Time (Month)
35
40
45
50
Tasks
Tasks
Tasks/Month
9
+
-
Data Often Tell a More Complex Story
Productivity
Work to Do
+
Staff
+
Work Being
Accomplished
Work Done
PRODUCTIVITY?
OR...
10
+
Effort is being spent elsewhere …
-
Productivity
Staff
Work to Do
x
WorkzBeing
Accomplished
Fraction Correct
and Complete (0-1: fraction
not to be
reworked)
y
Work
Done
Rework
Creation
Rework
Execution
Rework
Sep 11, 2007
11
+

Definitions
Productivity -Work accomplished per hour of effort,
regardless of completeness or correctness

Fraction Correct & Complete -Fraction of work just accomplished that will
not need rework. “Work Quality”
Later we will revisit the iron triangle to
consider “delivered quality.”
12
+
-
The Rework Cycle
Effort
Applied
Productivity
+
Original
Work to Do
Rework to
Do
+
Fraction Correct
and Complete
-
Progress
Rework
Generation
Progressx
Rew
ork
Rework
Discovery
-
+
Work Done
Undiscovered
Rework
Delay!
TimeintoDiscovering
Discover Rework
Delay
Rework
13
+
Adding Rework Delays Completion …
-
Work Done
Undiscovered Rework
1,000
60
No Rework
45
With
Rework
500
250
Tasks
Tasks
750
30
15
0
0
5
10
15
20
25
30
Time (Month)
Work Done : Traditional With Rework
Work Done : Traditional View
35
40
45
50
0
0
5
10
15
20
25
30
Time (Month)
35
40
45
50
Undiscovered Rework : Traditional With Rework
14
+
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So, What Happens on Projects?
Staff
Effort
on Initial
Work
Effort on
Rework
TIME
15
Rework creates and extended
staffing tail
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Simulated
Actual
800.
Work Assignments of Staff to...
800.
Disguised results from
actual aerospace
project
600.
Total
600.
Approximate
Original
Plan
… Staffing
experiences an
extended tail
400.
400.
Rework
200.
Original
Work
200.
0
0
3
6
9
Year
12
15
18
0
21
0
3
6
9
12
15
18
21
17
© 2001 John Wiley & Sons, Ltd. All rights reserved. This
content is excluded from our Creative Commons license.
For more information, see http://ocw.mit.edu/fairuse.
16
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… or a second staffing peak
-
Work Assignments of Staff to...
Program Staff, Simulated vs. Data (Equivalent Staff)
Simulated
Actual
Original Plan
Original Work
400.
Rework
400.
Disguised results from
actual vehicle project
Disguised results from
actual vehicle project
300.
300.
… A second
staffing peak
200.
200.
100.
Original
Work
Rework
100.
0
0
Year 1
Year 2
Year 3
Year 4
TIME
Year 5
Year 6
Year 1
20
Year 2
Year 3
Year 4
TIME
Year 5
Year 6
© 2001 John Wiley & Sons, Ltd. All rights reserved. This
content is excluded from our Creative Commons license.
For more information, see http://ocw.mit.edu/fairuse.
17
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Consequences of Undiscovered
Rework
Effort
Applied
Productivity
+
+
Progress
Fraction Correct
and Complete
-
Rework
Generation
Original
Work to Do
Work Done
Progressx
Rework to
Do
Rework
Discovery
Rework
Undiscovered
Rework
1.Overestimates
of Progress
18
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

Additional Metrics
(Used in Model)
Fraction Reported to be Complete =
(Work Done + Undiscovered Rework) /
Initial Work to Do
Fraction of Work Really Complete =
(Work Done) / Initial Work to Do
19
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Undiscovered rework generates
progress-measuring errors …
Progress
1
Reported
0.75
Fraction
+
Really
0.5
Undiscovered
Rework
0.25
0
0
5
10
15
20
25
30
Time (Month)
35
40
45
50
Fraction Reported Complete : Traditional With Rework3
Fraction Really Complete : Traditional With Rework3
20
Rework Cycle Creates
“The Lost-Year”...
+
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Design Progress (Percent Complete)
100.
Simulated
75.
The Lost Year
50.
Real Progress
25.
0.
Year 1
Year 2 Year 3
Year 4
Year 5
Year 6
Time
Source: Ken Cooper
Year 7
Year 8
Year 9
Disguised results
from actual
aerospace project
21
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and the “90% Syndrome” ---
-
Design Progress (Percent Complete)
100.
Simulated
75.
Disguised results
from actual
aerospace project
50.
25.
0.
1/85 1
Year
1/89
Year2
1/91 3
Year
1/934
Year
1/955
Year
1/976
Year
1/997 Year
1/01 8
Year
TIME
22
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Survey Question 1
Does your organization measure rework?
1.
Yes, we keep data on how much rework is
being discovered
2.
Yes, we keep data on how much work
being done is rework (vs original work)
3.
Yes, both 1 and 2
4.
No, we do not keep data on rework being
discovered
23
+
-
Survey Question 2
Does your organization recognize rework in
executing the project?
1.
Yes, by adjusting progress estimates to
reflect expected remaining undiscovered
rework
2.
Yes, by building rework tasks into the
project graph
3.
Both 1 and 2
4.
No, we only react as rework is discovered
24
+
-
Consequences of
Undiscovered Rework
Effort
Applied
Productivity
+
+
Progress
Fraction Correct
and Complete
-
Rework
Generation
Original
Work to Do
Work Done
Progressx
Rework to
Do
Rework
Discovery
Rework
Undiscovered
Rework
2. Build
Errors Into
Downstream
Work
1. Overestimates
of Progress
25
+
-
Survey Question 3
How significant is the “Errors on Errors”
feedback on typical projects in your
organization?
1. Very
2. Modest
3. Weak
4. None
26
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Units of Work – SD Model


“Tasks” -- ideally, of uniform size and
fungible
In actual applications, might use things like:





Drawings, work packages, lines of code, …
Tons of concrete, feet of steel, feet of wiring, ...
Parts designed
Sometimes %
Can represent “precedence” constraints
27
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“Quality”
Need to distinguish between:
 Instantaneous “work quality” (fraction
correct and complete)
 Delivered “quality” – remaining “bugs”
(undiscovered rework) when product
shipped
 Product capabilities, “fit and finish” (a
part of scope in model)
28
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Fraction Correct and Complete


Represents unplanned iterations;
planned iterations are separate tasks
Sources of errors many fold:



Mistakes from inexperience, fatigue, …
Technical complexity/uncertainty
Work done “correctly” but ultimately
needing rework because it builds on


Incorrect prior work
Assumptions about technology or customer
requirements which prove incorrect
29
+
Two Types of Iteration
-
Planned Iteration



Caused by needs to “get it
right the first time.”
We know where these
iterations occur, but not
necessarily how much.
Planned iterations should be
facilitated by good design
methods, tools, and
coordination.
Separate tasks in the rework
cycle
Unplanned Iteration



Caused by errors and/or
unforeseen problems.
We generally cannot predict
which unplanned iterations
will occur.
Unplanned iterations should
be minimized using risk
management methods.
“Quality” problems in the
rework cycle
30
+


Qualitative Insights
Undiscovered Rework is one of the most important
single factors driving schedule and budget overruns
Most management reporting systems overestimate
real progress and discourage reporting of rework
31
+
-
Lessons: Recognize the rework
cycle and minimize its consequences
Productivity
+
Original
Work to Do
Rework to
Do
+
-
Progress
Rework
Generation
Progressx
Rew
ork
Rework
Discovery
-
Reduce
Increase
Effort
Applied
Fraction
Quality
Correct and
Complete
Undiscovered
Rework
+
DelaytoinDiscover
Discovering
Rework
Time
Rework
Work Done
Build Errors
Into
Downstream
Work
Overestimates
of Progress
Be
Realistic
32
Dynamics of Project
Performance
+
-
The “rework cycle”


Fraction correct and complete 
Undiscovered rework 
Feedback effects on productivity and fraction
correct (Next class)


Negative, controlling
Positive, re-enforcing, often “vicious circles”
Knock-on effects between work phases (Next)


Availability and quality of work products
Progress to discover upstream rework
33
+
Today’s Agenda

Causes of Project Dynamics

The Rework Cycle

Integrating Tools in Project Planning

Simple Model of Project Dynamics, Pt. 1
34
+
Fundamental Approaches

Network-based (graph theory) methods



b
a
c
Matrix-based methods



CPM, PERT, ….
Task is a node or an arc



DSM - Tasks are columns and rows
Interrelationships are off-diagonal entries
Feedback loops, causal relationships
Stocks and flows simulation
Tasks that are done or waiting to be done
are stocks – “amount of work”
Doing project work causes a “flow”
What have we learned thus far?
e
x x
xx
x x
x x
x x
System Dynamics

d
W ORK
TO BE
DONE
PEO PLE
PRODUCTIVITY
W ORK
BEING DONE
W ORK
DONE
35
+
1
Network View of CityCar Project
-
3
2
4
23
7
5
6
13
8
12
15
9
11
10
14
17
16
18
22
24
19
21
27
20
28
25
26
30
31
29
32
33
34
35
37
36
39
38
40
Network Diagram for NMM Case
(from 2010 Homework #1)
+
-
i,
Diesel
Dev
c,
Diesel
Specs
d, Elec
Drive
Specs
a, Start
n,
Diesel
Delivery
j, Elec
Drive
Dev
b, Req
o,
Integra
tion
k,
Chassis
Design
e,
Layout
r,
Charging
Assembly
w,
Road
Test
m,
Internal
Fittings
y, Finish
t,
PowerVehicle
Integ
l, Body
Design
s, Body/
Chassis
Prototype
f,
Electronics
Design
p,
Electronics
Delivery
g, Soft
ware
Specs
Note: Diesel, Elec Drive,
and Software do not
show separate “design”
and “build” tasks.
U, Final
Assembly
v,
Dynamo
Lab Test
x, Car
Show
Setup
q,
Electronics
Software
Integ
h, Soft
ware
Dev
37
+
-
Organizing the Tasks by “Metatask”
Requirements
Definition
i,
Diesel
Dev
c,
Diesel
Specs
Body &
Chassis
Design
k,
Chassis
Design
b, Req
e,
Layout
g, Soft
ware
Specs
n,
Diesel
Delivery
Vehicle & Powertrain Integration
j, Elec
Drive
Dev
d, Elec
Drive
Specs
a, Start
Diesel & Electric
Drive Design
s, Body/
Chassis
Prototype
l, Body
Design
f,
Electronics
Design
o,
Integra
tion
Testing &
Completion
r,
Charging
Assembly
t,
PowerVehicle
Integ
w,
Road
Test
U, Final
Assembly
y, Finish
v,
Dynamo
Lab Test
m,
Internal
Fittings
x, Car
Show
Setup
p,
Electronics
Delivery
Final Assembly
h,
Software
Dev
q,
Electronics
Software
Integ
Electronics &
Software
Design
38
+
-
“Gantt” Chart with Metatasks Shown
Note: dates approximate; JML estimates of Diesel & Electric, Software Design/Build Split
2010
Jan Feb
Requirements Definition
a
b
c
d
g
Start
Requirements
Diesel Specs
Elec Drive Specs
Software Specs
1/1/10
60
1/1/10
3/25/10
a
30
3/25/10
5/6/10
b
30
3/26/10
5/6/10
b
72
3/26/10
7/5/10
b
40
3/26/10
6/1/10
b
6/2/10 10/21/10
e
Mar
Apr
May June July
Aug Sept
Oct
Nov
Dec
2011
Jan Feb
Mar
Apr
May June July
Aug Sept
Oct
Nov
Dec
Requirements
Design
Build/Test
Coupled
Body & Chassis
e
k
l
s
Layout
Chassis Design
Body Design
Body Chassis Prototype
102
90
6/2/10
10/5/10
e
48 10/22/10 12/28/10
k,l
Electronics & Software
f
h
p
q
Electronics Design
Software Dev
Electronics Delivery
Electronics Software Int
90
5/7/10
150
9/10/10
72
9/9/10 b,c,d
4/7/11
9/10/10 12/20/10
g,f
g,f
30
4/8/11
5/19/11
h,p
180
5/7/10
1/13/11
c
90
5/7/10
9/9/10
d
12
1/14/11
1/31/11
i
60
2/1/11
4/25/11
j,n
12
4/26/11
5/11/11
j,o
60
5/20/11
8/11/11 q,r,s
Diesel & Electric Drive
i
j
n
Diesel Dev
Elec Drive Dev
Diesel Delivery & Check
Vehicle & Power Train Int
o
r
t
Integration
Charging Assembly
Power Vehicle Int
Final Assembly
m
u
Internal Fittings
Final Assembly
48 10/22/10 12/28/10
k,l
30
8/12/11
9/22/11
m,t
30
9/23/11
11/3/11
u
72
11/4/11
2/13/12
v
45
11/4/11
1/5/12
v
Testing & Completion
v
w
x
y
Dynamo Lab Test
Road Test
Car Show Setup
Finish
2/13/12
39
What Messages Come From DSM and
SD regarding the network/Gantt plan?
+

DSM ?




SD ?




How/when is rework discovered?
40
+
-
DSM Identifies Coupled Tasks & Areas of
Unplanned Iterations (from Homework #2)
Requirements
Definition
i,
Diesel
Dev
c,
Diesel
Specs
Body &
Chassis
Design
k,
Chassis
Design
b, Req
e,
Layout
g, Soft
ware
Specs
n,
Diesel
Delivery
Vehicle & Powertrain Integration
j, Elec
Drive
Dev
d, Elec
Drive
Specs
a, Start
Diesel & Electric
Drive Design
s, Body/
Chassis
Prototype
l, Body
Design
f,
Electronics
Design
o,
Integra
tion
Testing &
Completion
r,
Charging
Assembly
t,
PowerVehicle
Integ
w,
Road
Test
U, Final
Assembly
y, Finish
v,
Dynamo
Lab Test
m,
Internal
Fittings
x, Car
Show
Setup
p,
Electronics
Delivery
Final Assembly
h,
Software
Dev
q,
Electronics
Software
Integ
Electronics &
Software
Design
Coupled Tasks – Possible
planned Iterations (in design)
Unplanned Iterations (why not
back to design phase?)
41
+
-
“Gantt” Chart With Coupled Tasks Shown
2010
Jan Feb
Requirements Definition
a
b
Start
Requirements
60
1/1/10
3/25/10
a
c
Diesel Specs
30
3/25/10
5/6/10
b
d
g
Elec Drive Specs
Software Specs
30
3/26/10
5/6/10
b
72
3/26/10
7/5/10
b
40
3/26/10
6/1/10
b
6/2/10 10/21/10
e
1/1/10
Body & Chassis
e
Layout
k
l
Chassis Design
Body Design
s
Body Chassis Prototype
102
90
6/2/10
10/5/10
e
48 10/22/10 12/28/10
k,l
Electronics & Software
f
h
Electronics Design
Software Dev
p
q
Electronics Delivery
Electronics Software Int
90
5/7/10
150
9/10/10
72
9/9/10 b,c,d
4/7/11
9/10/10 12/20/10
g,f
Mar
Apr
May June July
Aug Sept
Oct
Nov
Dec
Requirements
Design
Build/Test
Coupled
2011
Jan Feb
Mar
Apr
May June July
Aug Sept
Oct
Nov
Dec
Observation/
Question: no
coupling
between major
design phases?
g,f
30
4/8/11
5/19/11
h,p
180
5/7/10
1/13/11
c
90
5/7/10
9/9/10
d
12
1/14/11
1/31/11
i
60
2/1/11
4/25/11
j,n
12
4/26/11
5/11/11
j,o
60
5/20/11
8/11/11 q,r,s
Diesel & Electric Drive
i
j
Diesel Dev
Elec Drive Dev
n
Diesel Delivery & Check
Vehicle & Power Train Int
o
r
t
Integration
Charging Assembly
Power Vehicle Int
Final Assembly
m
u
Internal Fittings
Final Assembly
48 10/22/10 12/28/10
k,l
30
8/12/11
9/22/11
m,t
30
9/23/11
11/3/11
u
72
11/4/11
2/13/12
v
45
11/4/11
1/5/12
v
Testing & Completion
v
w
x
y
Dynamo Lab Test
Road Test
Car Show Setup
Finish
2/13/12
42
Network Diagram With “Build” Steps Added and
Major Work Phases Highlighted
+
-
Requirements
i,
Diesel
Dev
c,
Diesel
Specs
i*,
Diesel
Build
n,
Diesel
Delivery
j, Elec
Drive
Dev
j*, Elec
Drive
Build
d, Elec
Drive
Specs
a, Start
Build/Test
Design
k,
Chassis
Design
b, Req
e,
Layout
s, Body/
Chassis
Prototype
l, Body
Design
g, Soft
ware
Specs
o,
Integra
tion
r,
Charging
Assembly
t,
PowerVehicle
Integ
U, Final
Assembly
f*,
Electronics
"Build"
p,
Electronics
Delivery
y, Finish
v,
Dynamo
Lab Test
m,
Internal
Fittings
f,
Electronics
Design
w,
Road
Test
x, Car
Show
Setup
q,
Electronics
Software
Integ
h*,
Software
"Build"
h,
Software
Dev
43
+
-
In an SD Model, Each Phase of Work
Could Be Represented by a Rework Cycle
Staff
Staff on
Original Work
Staff on Rework
Productivity
Original Work Being
Accomplishmed
<Initial Work to
Do>
Rework Being
Accomplishmed
Original Work Done Correctly
Original
Work to Do
Rework Generation on
Original Work
Work Done
Fraction Correct
and Complete
Rework to Do
Rework
Generation on
Rework
Undiscovered
Rework
Rework
Discovery
44
+
… Expanded to Three Phases
-
Design
Requirements
Requriements Staff
Design Staff
Rqmnts Staff on
Original Work
Rqmnts Staff on
Rework
Rqmnts Original Work
Being Accomplishmed
Requirements
Fraction Correct and
Complete
Rqmnts Rework
Generation on Original
Work
Rqmnts
Rework to Do
Rqmnts Rework
Generation on
Rework
Rqments
Undiscovered
Rework
Rqmnts Rework
Discovery
Assumptions:
Scope = 100 Tasks
Staff = 4,
Productivity = 2 tasks/month/person
Duration = 12.5 months
Design Fraction
Correct and
Complete
Build/Test Staff
on Rework
Build/Test Productivity
Design Original Work
Being Accomplishmed
<Build/Test Initial
Work to Do>
Rqments
Work Done
Build/Test Staff on
Original Work
Design Staff on
Rework
Design Productivity
Rqmnts Rework
Being
Accomplishmed
Rqmnts Original Work Done Correctly
Rqmnts
Original
Work to Do
Build/Test Staff
Design Staff on
Original Work
Requirements Productivity
<Build/Test Initial
Work to Do>
Build/Test
Design Rework
Being
Accomplishmed
Build/test Original
Work Being
Accomplishmed
Build/Test Rework
Being Accomplishmed
Design Original Work Done Correctly
<Build/Test Initial
Work to Do>
Design
Original
Work to Do
Design Rework
Generation on Original
Work
Build/Test Original Work Done Correctly
Build/Test
Original
Work to Do
Build/Test Rework
Generation on Original
Work
Design Work
Done
Design
Rework to Do
Design Rework
Generation on
Rework
Design
Undiscovered
Rework
Design Rework
Discovery
Scope = 1000 tasks
Staff = 20
Productivity = 4 tasks/month/person
Duration = 12.5 months
Build/Test Fraction
Correct and Complete
Build/Test
Work Done
Build/Test
Rework to Do
Build/Test Rework
Generation on Rework
Build/Test
Undiscovered
Rework
Build/Test Rework
Discovery
Scope = 1000 tasks
Staff = 40
Productivity = 1 tasks/month/person
Duration = 25 months
45
Simulation of project assuming
no rework …
+
-
Project Staff
2,000
60
1,500
45
Design
1,000
People
Task
Work Done
Total
Build/Test
Design
30
15
500
Build/Test
Requirements
Requirements
0
0
0
6
12
18
24
30
36
Time (Month)
Requirements Work Done : Three P Four Stock No Rework Discrete Start
Design Work Done : Three P Four Stock No Rework Discrete Start
"Build/Test Work Done" : Three P Four Stock No Rework Discrete Start
42
48
54
60
0
6
12
18
24
30
36
Time (Month)
42
48
54
60
Requirements Staff : Three P Four Stock No Rework Discrete Start
Design Staff : Three P Four Stock No Rework Discrete Start
"Build/Test Staff" : Three P Four Stock No Rework Discrete Start
Project Staff : Three P Four Stock No Rework Discrete Start
46
+
-
1.
2.
3.
Sources of Rework -- Categories
Classical “Quality” or design misexecution.
Technical complexity/uncertainty;
customer uncertainty.
Work done “correctly” but ultimately
needing rework because it builds on
47
+
Classical “Quality”
-

There are two (or more) important sources of these
errors –




“People” factors such as fatigue, inexperience, skill mismatches,
etc.
“Coupled” tasks that require shared information but which are done
independently
Organizational size & complexity?
These types of errors can in theory be discovered
by further “design” work, such as doing
downstream design work, QA, design reviews,
planned iteration, etc.
48
+



Technical complexity/uncertainty;
customer uncertainty.
Technical: “novelty” of the project
Customer: Same logic might apply to novel/new
“uncertain customer requirements”? I.e., where say
a software product is being developed and the
customer may not know what they want until they
see it in practice.]
These types of errors can only be discovered
by doing build and test work. Fixing these
errors may just require redoing tasks, but may
also require new tasks to make the technology
work (e.g., and additional controller).
49
+
“Knock-on” Rework

Work done “correctly” but ultimately needing
rework because it builds on




Incorrect prior work
Assumptions about technology or customer requirements
which prove incorrect.
Exogenous changes in requirements, scope, etc.
These errors could be discovered in
design or build/test, depending on the
source.
50
+
How does Design Affect Build?
-
Design Staff
Build/Test Staff
Design Staff on
Original Work
Build/Test Staff on
Original Work
Design Staff on
Rework
Design Productivity
Design Original Work
Being Accomplishmed
<Build/Test Initial
Work to Do>
Build/Test Staff
on Rework
Build/Test Productivity
Design Rework
Being
Accomplishmed
Build/test Original
Work Being
Accomplishmed
Build/Test Rework
Being Accomplishmed
<Build/Test Initial
Work to Do>
Design Original Work Done Correctly
Build/Test Original Work Done Correctly
Design
Original
Work to Do
Design Fraction
Correct and
Complete
Design Rework
Generation on Original
Work
Design
Rework to Do
Design Rework
Generation on
Rework
Design
Undiscovered
Rework
Build/Test
Original
Work to Do
Build/Test Rework
Generation on Original
Work
Design Work
Done
Design Fraction
Reported Complete
Design Rework
Discovery
Design Fraction of Work
Done Correct and
Complete
Build/Test Fraction
Correct and Complete
Build/Test
Work Done
Build/Test
Rework to Do
Build/Test Rework
Generation on Rework
Build/Test Rework
Discovery
Build/Test
Undiscovered
Rework
Build/Test Fraction
Reported Complete
51
+
How is Design Rework Discovered?
-
Design Staff
Build/Test Staff
Design Staff on
Original Work
Build/Test Staff on
Original Work
Design Staff on
Rework
Design Productivity
Design Original Work
Being Accomplishmed
<Build/Test Initial
Work to Do>
Build/Test Staff
on Rework
Build/Test Productivity
Design Rework
Being
Accomplishmed
Build/test Original
Work Being
Accomplishmed
Build/Test Rework
Being Accomplishmed
<Build/Test Initial
Work to Do>
Design Original Work Done Correctly
Build/Test Original Work Done Correctly
Design
Original
Work to Do
Design Fraction
Correct and
Complete
Design Rework
Generation on Original
Work
Design
Rework to Do
Design Rework
Generation on
Rework
Design
Undiscovered
Rework
Build/Test
Original
Work to Do
Build/Test Rework
Generation on Original
Work
Design Work
Done
Design Fraction
Reported Complete
Design Rework
Discovery
Design Fraction of Work
Done Correct and
Complete
Build/Test Fraction
Correct and Complete
Build/Test
Work Done
Build/Test
Rework to Do
Build/Test Rework
Generation on Rework
Build/Test Rework
Discovery
Build/Test
Undiscovered
Rework
Build/Test Fraction
Reported Complete
52
Simulation Incorporating Rework and
Rework Discovery
+
-
Project Staff
1,000
80
750
60
Design
500
People
Task
Work Done
Build/Test
Total
40
Requirements
0
0
0
6
Design
20
Requirements
250
0
Build/Test
12
18
24
30
36
Time (Month)
Requirements Work Done : Three Phase Four Stock V1
Design Work Done : Three Phase Four Stock V1
"Build/Test Work Done" : Three Phase Four Stock V1
42
48
54
60
6
12
18
24
30
36
Time (Month)
42
48
54
60
Requirements Staff : Three Phase Four Stock V1
Design Staff : Three Phase Four Stock V1
"Build/Test Staff" : Three Phase Four Stock V1
Project Staff : Three Phase Four Stock V1
Notes: (1) Details of simulation do not correspond to NMM Case;
(2) so far, we do not represent project control actions and effects,
so staff/hours worked are constant.
53
+
-
Design Stocks
1,000
Original Work
Work Done
Task
750
500
Rework
250
Undiscovered
Rework
-0.0001
0
0
Design
Design
Design
Design
6
12
18
24
30
36
Time (Month)
42
48
54
60
Original Work to Do : Three Phase Four Stock V1
Undiscovered Rework : Three Phase Four Stock V1
Rework to Do : Three Phase Four Stock V1
Work Done : Three Phase Four Stock V1
54
+
Progress and Rework Discovery
-
Design Fraction Complete
Fraction Design Rework Discovered
2
0.8
Original Reported
Work
Really
1
0.5
0
0
6
12
18
24
30
36
Time (Month)
Design Fraction Original Work Complete : Three Phase Four Stock V1
Design Fraction Reported Complete : Three Phase Four Stock V1
Design Fraction Really Complete : Three Phase Four Stock V1
42
48
0.6
Fraction
Fraction
1.5
0.4
0.2
54
60
0
0
6
12
18
24
30
36
Time (Month)
42
48
54
60
Fraction Design Rework Discovered : Three Phase Four Stock V1
Discovery
by design
Discovery
by build
55
Rework Increases Cost
and Delays Finish
+
-
With Rework
Without Rework
Cumulative Effort
Cumulative Effort
2,000
2,000
Total
Build/Test
1,000
Design
500
0
Person*Months
Person*Months
1,500
1,500
1,000
500
0
0
6
12
18
24
30
36
Time (Month)
Cumulative Reqmnts Effort : Three Phase Four Stock V1
Cumulative Design Effort : Three Phase Four Stock V1
"Cumulative Build/Test Effort" : Three Phase Four Stock V1
Cumulative Effort : Three Phase Four Stock V1
42
48
54
60
Requirements
0
6
12
18
24
30
36
Time (Month)
42
48
54
60
Cumulative Reqmnts Effort : Three P Four Stock No Rework
Cumulative Design Effort : Three P Four Stock No Rework
"Cumulative Build/Test Effort" : Three P Four Stock No Rework
Cumulative Effort : Three P Four Stock No Rework
56
Revised Network/Gantt to reflect
rework discovery (by build, not design)
+
-
Insert some Rework Tasks in
Design, more in Build/Test
2010
Apr May June July
Aug Sept
Oct
Nov
Dec
2011
Jan Feb
Mar
Apr
May June July
Electronics & Software -- Original
f
Electronics Design
h
Software Dev
p
q
Electronics Delivery
Electronics Software Int
90
5/7/10
150
9/10/10
72
30
9/9/10 b,c,d
4/7/11
g,f
9/10/10 12/20/10
g,f
4/8/11
5/19/11
Electronics Design
h
Software Dev
p
Electronics Delivery
72
q
Electronics Software Int
30
90
5/7/10
150
9/10/10
9/9/10 b,c,d
4/7/11
9/10/10 12/20/10
4/8/11
5/19/11
Oct
Design
Build/Test
Coupled
R
Nov
Dec
Rework
h,p
Electronics & Software -- Rework Discovered in Build/Test
f
Aug Sept
g,f
g,f
h,p
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
57
+
Management Issues



Planned Iterations (vs dealing with unplanned
iterations later) – How many iterations?
When to start build phases – how much overlap with
design phases.
Factors to Consider:


Type of project (determines amount of rework discoverable
in design, amount of rework, number of tasks which must be
repeated for each iteration)
Relative cost of design vs build/test (determines the relative
cost of spending more in design)
More on these later in term …
58
+
Role of Tools

SD:



DSM:


Evaluate the macro tradeoffs in terms of impact
on cost and schedule
Coming up with a good staffing plan
Determine where design iterations are needed and
how many tasks would need to be repeated per
iteration
Network:

Guide operational task planning and resource
scheduling
59
Dynamics of Project
Performance
+
-
The “rework cycle”


Fraction correct and complete 
Undiscovered rework 
Feedback effects on productivity and fraction
correct (Next class)


Negative, controlling
Positive, re-enforcing, often “vicious circles”
Knock-on effects between work phases


Availability and quality of work products 
Progress to discover upstream rework 
60
+
-
Knock-on Between Phases: A system dynamics
model usually represents several phases of work …
 Rework Discovery Effects
S o ftw a re
D e s ig n
S o ftw a re C o d e
and Test
S y s te m
E n g in e e rin g
Productivity and Fraction Correct Effects
(availability and quality of upstream work) 
H a rd w a re
D e s ig n
Notes:
Suppliers might
be a “phase”
In te g ra te
and Test
H a rd w a re B u ild
and Test
61
+






Why Represent Separate Phases?
Correspond to gate reviews and deliverables
Different units of work (and therefore data)
Different types of labor
Disproportionate increase in costs of fixing
errors as move downstream
Address issues of overlap/concurrency
Opportunity to adjust plans, delay start,
between phases
62
+
Today’s Agenda

Overview: Causes of Project Dynamics

The Rework Cycle

Integrating Tools in Project Planning

Simple Model of Project Dynamics, Pt. 1
63
+
-
Hard tools force us to be more explicit, and
accurately simulate the consequences of our
models ...
“Soft” tools - behavior-overtime graphs
 cause-effect
diagramming
 mental simulation
“Hard” tools - computer models
 computer
simulation
 calibration to data
 sensitivity and
what-if analyses
Tools for describing
dynamics
Tools for quantifying
dynamics
64
+
We will use two models …

Simple rework cycle model with project
control feedbacks



HW#3 – develop simple model without
feedbacks
Feedbacks added in class, given in HW#5
Full rework cycle model with two
phases of work


No project control feedback
Model given to you for HW#3 and HW#5
65
+
Development of “Simple” Project Model 1

Rework cycle model (HW#3)




Three stocks
Variable rework discovery time
“Errors Build Errors” Feedback
Project control & Side Effects (HW#5)



Work Intensity/Schedule Pressure & “Haste
Makes Waste”
Staffing & Experience Dilution
Slip Schedule
66
+
Two Views of the Rework Cycle
-
Complete Model
Fraction
Correct &
Complete
Simplified Version
Work Accomplishment
Progress
Original
Work to Do
Progressx
Rework to
Do
Rework
Discovery
Rework
Work Done
Work to Do
Rework Generation
Undiscovered
Rework
Work Done
Undiscovered
Rework
Rework Discovery
The simplified version assumes that
rework tasks require the same effort
as original tasks, and that it is not
important to distinguish between
original work and rework.
67
+
Simple Rework Cycle Model
-
Productivity
+
Potential Work Rate
Based on Staffing +
Levels
Minimum Time to
Finish a Task
Fraction Correct
and Complete
Normal Staff
+
+
+ Work Being
Accomplished
Maximum Work Rate
Based on Tasks
Available
Staff
+
+
+
Work to Do
Effort Expended
Work Done
Correctly
Rework Generation
Undiscovered
Rework
Work Done
Cumulative
Effort
Expended
Project Finished
+
- -
Fraction Complete
to Finish
Initial Work to
Do
<Initial Work to
Do>
<Rework Generation>
Rework Discovery
Time to Discover
Rework
Steps 1-4 of
Homework #3
Rate of Doing Work
Cumulative
Work Done
<Project Finished>
<Work Done Correctly>
68
+
-
Rework Discovery Depends on Progress
69
+
Complete Simple Model 1
-
“Errors on
Errors”
Feedback
Productivity
Potential Work Rate
Based on Staff
Minimum Time to
Finish a Task
Normal Fraction
Correct and Complete
Maximum Work Rate
Based on Tasks
Available
Fraction Correct
and Complete
Normal Staff
Staff
Work Being
Accomplished
Work Done
Correctly
Effort Expended
Sensitivity of Fraction
Correct to Undiscovered
Rework
Effect of Undiscovered
Rework on Fraction
Correct
Maximum Effect of
Undiscovered Rework on
Fraction Correct
Work to Do
Rework Generation
Undiscovered
Rework
Cumulative
Effort
Expended
Project Finished
Work Done
Fraction Complete
to Finish
Initial Work to
Do
<Initial Work to
Do>
Rework Discovery
<Project Finished>
Delay in
Discovering Rework
Fraction of Work
Believed Done Correct
and Complete
This reflects the average delay in
discovering discoverable rework ,
such as from QA activities or
downstream work .
Work Believed to
Be Done
Fraction of Rework Discovered
<Work Done>
This reflects the fraction of
undiscovered rework that is
discoverable at any point in the project
based on the activities tak ing place.
<Rework Generation>
Rate of Doing Work
Fraction Really
Complete
Fraction Reported
Complete
Cumulative
Work Done
<Work Done Correctly>
<Initial Work to Do>
70
+
-
Effect of Undiscovered Rework on
Fraction Correct:
Effect of Undiscovered Rework on
Fraction
Correct
Graph
Lookup - Table
for Effect of Prior Work Quality on Quality
1
0
0
Average
Fraction
of Work
Work Quality
Believed
Done Correct and Complete
1
Note: The effect of undiscovered rework on fraction correct is assumed to be
proportional -- an error in past work creates an error in current work. Given that in this
simple model fraction correct represents several effects of work errors, this strong
relationship may be reasonable.
71
Work Flows & Staffing in “Simple”
Two Phase Model
+
-
Design
Build/Test
Project Staff
<Staff On
Review>
End Design
Rampup
Start Design
Rampup
Fraction Design
Complete to Start Build
<TIME STEP>
Rampup
Design Staff
Total
Design Startup
<Time>
Build/Test
Planned Staff
Duration of Build
Rampup
Time to Start
Build Ramp Up
Design Staff
Design
Planned Staff
Design Fraction of
Effort to Rework
<Time>
Build/Test
Startup
Build/Test Staff
Build/Test Fraction
of Effort to Rework
Design Staff on
Rework
Design Staff on
Original Work Design Relative Effort
Required for Rework
Design
Indicated Staff
Design Maximum Work
Rate Based on Rework
Tasks Available
<Design
Productivity>
Design Original Work
Being Accomplishmed
Design Minimum
Time to Finish a Task
Design Initial
Work to Do
Normal Design
Fraction Correct
and Complete
Design Effect of
Undiscovered Rework on
Fraction Correct
Design Fraction
Reported Complete
<Initial Build/Test
Work to Do>
Design Rework
Generation on
Rework
<Design Rework
Discovered By
Design>
<Design Initial
Work to Do>
Normal Build/Test
Fraction Correct and
Complete
Design Rework
Discovery
Build/Test
Build/Test Rework Work Done
Done Correctly
Build/Test
Build/Test Rework Undiscovered
Generation on Rework Rework
<Initial Build/Test
Work to Do>
Build/Test Rework
Discovery
Build/Test Delay in
Discovering Rework
Sensitivity of Build/Test
Fraction Correct to Design
Undiscovered Rework
<Design
Rework to Do>
Switch to Include
Rework
Project Finished
Switch
Build/Test Work
Believed to Be Done
<Initial Build/Test
Work to Do>
Design Fraction of Work
Done Correct and
Complete
<Design Remaining
Rework Discovered by
Build>
Build/Test Rework
Being Accomplishmed
Build/Test Rework
Generation on Original
Work
Build/Test Effect of Design
Undiscovered Rework On
Fraction Correct
Design Work
Believed to Be Done
<Build/Test
Productivity>
Build/Test Original
Work Done Correctly
Build/Test
Original
Work to Do
Build/Test Fraction
Correct and Complete
<Design Rework
Discovered By Build>
<Fraction Rework
Being Discovered>
Build/Test Original
Work Being
Accomplishmed
Build/Test
Rework to Do
Design
Undiscovered
Rework
Staff on Rework
Build/Test Priority
to Original Work
Build/Test
Productivity on
Rework
Build/Test Minimum
Time to Finish a Task
Design Work
Design Rework
Done
Done Correctly
Design
Rework to Do
Sensitivity of Design
Fraction Correct to Design
Undiscovered Rework
Maximum Sensitivity of
Design Fraction Correct to
Design Undiscovered Rework
Design Rework
Being
Accomplishmed
Design Rework
Generation on Original
Work
<Design Delay in
Discovering Rework>
<Maximum Effect of
Undiscovered Rework on
Fraction Correct>
Build/Test Staff on
Original Work
Build/Test Maximum Work
Rate Based on Original
Work Tasks Available
Design Original
Work Done Correctly
Design
Original
Work to Do
Design Fraction
Correct and
Complete
Build/Test Maximum Work
Rate Based on Rework
Tasks Available
Design
Productivity on
Rework
Design Maximum Work
Rate Based on Original
Work Tasks Available
Build/Test Relative
Effort Required for
Rework
Build/Test
Indicated Staff
Design Priority to
Original Work
Maximum Effect of
Undiscovered Rework on
Fraction Correct
Build/Test Fraction of Work
Believed Done Correct and
Complete
Sensitivity of Build/Test
Fraction Correct to Build
Undiscovered Rework
<Effect of Build Progress
on Build/Test Rework
Discovery>
Four Stock
Rework Cycle
Build/Test Fraction
Reported Complete
Build/Test Effect of Build
Undiscovered Rework on
Fraction Correct
<Design Effect of Build
Work on Rework
Discovery>
Maximum Sensitivity of
Build/Test FCC to Design
Undiscovered Rework
<Fraction Build/Test
Rework Discovered>
Maximum Sensitivity of
Build/Test Fraction Correct to
Build Undiscovered Rework
<Switch to
Include Rework>
<Build/Test
Rework to Do>
72
+
-
Design Phase of Work (Build/Test Similar)
Design
Staff
Project Staff
<Staff On
Review>
End Design
Rampup
Start Design
Rampup
Allocation
of Staff
Based on
Backlogs,
etc.
Fraction Design
Complete to Start Build
Rampup
Design Staff
Total
Design Startup
<Time>
Design Staff
Design
Planned Staff
Design Fraction of
Effort to Rework
Design Staff on
Rework
Design Staff on
Original Work Design Relative Effort
Required for Rework
Design
Indicated Staff
Design Maximum Work
Rate Based on Rework
Tasks Available
Design Maximum Work
Rate Based on Original
Work Tasks Available
<Design
Productivity>
Design Original Work
Being Accomplishmed
Design Minimum
Time to Finish a Task
Design Initial
Work to Do
Normal Design
Fraction Correct
and Complete
“Errors
Create
Errors”
Feedback
Design Effect of
Undiscovered Rework on
Fraction Correct
Design Rework
Done Correctly
Design
Rework to Do
Design Rework
Generation on
Rework
<Design Rework
Discovered By
Design>
Design Work
Done
<Design Initial
Work to Do>
Design
Undiscovered
Rework
Design Rework
Discovery
Design Work
Believed to Be Done
Design Fraction of Work
Done Correct and
Complete
<Design Remaining
Rework Discovered by
Build>
<Design Rework
Discovered By Build>
Sensitivity of Design
Fraction Correct to Design
Undiscovered Rework
Maximum Sensitivity of
Design Fraction Correct to
Design Undiscovered Rework
Design Fraction
Reported Complete
Design Rework
Generation on Original
Work
<Design Delay in
Discovering Rework>
<Maximum Effect of
Undiscovered Rework on
Fraction Correct>
Design Rework
Being
Accomplishmed
Design Original
Work Done Correctly
Design
Original
Work to Do
Design Fraction
Correct and
Complete
Design Priority to
Original Work
Design
Productivity on
Rework
Rework
Discovery
<Design
Rework to Do>
Switch to Include
Rework
<Fraction Rework
Being Discovered>
73
+
Phase Interconnections
-
Design
Build/Test
Design
Rework on
Build/Test
Productivity
Project Staff
<Staff On
Review>
End Design
Rampup
Start Design
Rampup
Fraction Design
Complete to Start Build
<TIME STEP>
Rampup
Design Staff
Total
Design Startup
<Time>
Build/Test
Planned Staff
Duration of Build
Rampup
Time to Start
Build Ramp Up
Design Staff
Design
Planned Staff
Design Fraction of
Effort to Rework
<Time>
Build/Test
Startup
Build/Test Staff
Build/Test Fraction
of Effort to Rework
Design Staff on
Rework
Design Staff on
Original Work Design Relative Effort
Required for Rework
Design
Indicated Staff
Design Maximum Work
Rate Based on Rework
Tasks Available
<Design
Productivity>
Design Original Work
Being Accomplishmed
Design Minimum
Time to Finish a Task
Design Initial
Work to Do
Normal Design
Fraction Correct
and Complete
Design Effect of
Undiscovered Rework on
Fraction Correct
Design Fraction
Reported Complete
<Initial Build/Test
Work to Do>
Design Rework
Generation on
Rework
<Design Rework
Discovered By
Design>
<Design Initial
Work to Do>
Normal Build/Test
Fraction Correct and
Complete
Design Rework
Discovery
Build/Test
Build/Test Rework Work Done
Done Correctly
Build/Test
Build/Test Rework Undiscovered
Generation on Rework Rework
<Design
Rework to Do>
Build/Test
Progress On
Design Rework
Discovery
<Initial Build/Test
Work to Do>
Build/Test Rework
Discovery
Build/Test Delay in
Discovering Rework
Sensitivity of Build/Test
Fraction Correct to Design
Undiscovered Rework
Switch to Include
Rework
Project Finished
Switch
Build/Test Work
Believed to Be Done
<Initial Build/Test
Work to Do>
Design Fraction of Work
Done Correct and
Complete
<Design Remaining
Rework Discovered by
Build>
Build/Test Rework
Being Accomplishmed
Build/Test Rework
Generation on Original
Work
Build/Test Effect of Design
Undiscovered Rework On
Fraction Correct
Design Work
Believed to Be Done
<Build/Test
Productivity>
Build/Test Original
Work Done Correctly
Build/Test
Original
Work to Do
Build/Test Fraction
Correct and Complete
<Design Rework
Discovered By Build>
<Fraction Rework
Being Discovered>
Build/Test Original
Work Being
Accomplishmed
Build/Test
Rework to Do
Design
Undiscovered
Rework
Staff on Rework
Build/Test Priority
to Original Work
Build/Test
Productivity on
Rework
Build/Test Minimum
Time to Finish a Task
Design Work
Design Rework
Done
Done Correctly
Design
Rework to Do
Sensitivity of Design
Fraction Correct to Design
Undiscovered Rework
Maximum Sensitivity of
Design Fraction Correct to
Design Undiscovered Rework
Design Rework
Being
Accomplishmed
Design Rework
Generation on Original
Work
<Design Delay in
Discovering Rework>
<Maximum Effect of
Undiscovered Rework on
Fraction Correct>
Build/Test Staff on
Original Work
Build/Test Maximum Work
Rate Based on Original
Work Tasks Available
Design Original
Work Done Correctly
Design
Original
Work to Do
Design Fraction
Correct and
Complete
Build/Test Maximum Work
Rate Based on Rework
Tasks Available
Design
Productivity on
Rework
Design Maximum Work
Rate Based on Original
Work Tasks Available
Build/Test Relative
Effort Required for
Rework
Build/Test
Indicated Staff
Design Priority to
Original Work
Maximum Effect of
Undiscovered Rework on
Fraction Correct
Build/Test Fraction
Reported Complete
Build/Test Effect of Build
Undiscovered Rework on
Fraction Correct
Build/Test Fraction of Work
Believed Done Correct and
Complete
<Design Effect of Build
Work on Rework
Discovery>
Design “Errors”
(Rework) on
Build/Test Fraction
Correct
Maximum Sensitivity of
Build/Test FCC to Design
Undiscovered Rework
<Fraction Build/Test
Rework Discovered>
Sensitivity of Build/Test
Fraction Correct to Build
Undiscovered Rework
<Effect of Build Progress
on Build/Test Rework
Discovery>
Maximum Sensitivity of
Build/Test Fraction Correct to
Build Undiscovered Rework
<Switch to
Include Rework>
<Build/Test
Rework to Do>
74
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ESD. 6\VWHP3URMHFW0DQDJHPHQW
Fall 2012
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