Transcript Project Management - Bienvenido a Libroweb — LibroWeb

Resource Allocation & Leveling
Resource Leveling: Reschedule the noncritical
tasks to smooth resource requirements
Resource Allocation: Minimize project
duration to meet resource availability constraints
Resource Allocation & Leveling
Three types of resources:
1) Renewable resources: “renew” themselves
at the beginning of each time period (e.g.,
workers)
2) Non-Renewable resources: can be used at
any rate but constraint on total number
available
3) Doubly constrained resources: both
renewable and non-renewable
Resource Leveling
Task C
9 wk s
Task A
3 wk s
Task D
5 wk s
S TART
Task G
5 wk s
Task B
2 wk s
END
Task E
3 wk s
Task F
2 wk s
Task
A
B
C
D
E
F
G
W ork e rs
7
3
2
10
4
5
6
Du rati on (tj)
3
2
9
5
3
2
5
Earl y S tart
0
0
3
3
2
2
8
Late S tart
0
3
4
3
5
11
8
Resource Leveling: Early Start Schedule
Resource Leveling: Late Start Schedule
Resource Leveling: Microsoft Project
Dec 17, '00
T
Dec 24, '00
W
T
10
10
F
S
S
Dec 31, '00
M
T
W
T
F
10
10
10
10
10
S
S
Jan 7, '01
M
T
W
T
F
10
10
16
16
16
S
S
M
T
W
T
F
16
16
21
21
21
25
20
15
10
5
Wor kers
10
Overallocated:
Allocated:
S
Renewable Resource Allocation Example
(Single Resource Type)
3 workers
6 workers
Task A
4 wks
Task C
1 wk
Task E
4 wks
START
Task B
3 wks
Task D
5 wks
5 workers
8 workers
7 workers
Maximum number of workers available = R = 9 workers
END
Resource Allocation Example: Early Start Schedule
Task C :
6 work e rs
Task A:
3 work e rs
S tart
En d
Task B:
5 work e rs
Task E:
7 work e rs
Task D:
8 work e rs
Week
1
2
3
4
5
6
7
8
9
10
11
12
No. of W orke rs /wk 8
C u mu l ati ve Work e rs 8
"Was te d" work e r-wk s 1
8
16
1
8
24
1
11
35
-
14
49
-
8
57
-
8
65
-
8
73
-
7
80
-
7
87
-
7
94
-
7
101
-
Maximum number of workers available = R = 9 workers
Resource Allocation Example: Late Start Schedule
Task A:
3 work e rs
S tart
Task C :
6 work e rs
En d
Task B:
5 work e rs
Task E:
7 work e rs
Task D:
8 work e rs
Week
1
2
3
4
5
6
7
8
9
10
11
12
No. of W orke rs /wk 5
C u mu l ati ve Work e rs 5
"Was te d" work e r-wk s -
5
10
-
5
15
-
11
26
-
11
37
-
11
48
-
11
59
-
14
73
-
7
80
2
7
87
2
7
94
2
7
101
2
Maximum number of workers available = R = 9 workers
Resource Allocation Heuristics
n
Some heuristics for assigning priorities to available tasks j, where
number of units of resource k used by task j
Choose first available task
R kj denotes the
n
1) FCFS:
n
2) GRU: (Greatest) resource utilization =
n
3) GRD: (Greatest) resource utilization x task duration =
n
4) ROT: (Greatest) resource utilization/task duration =
n
5) MTS: (Greatest) number of total successors
n
6) SPT: Shortest processing time = min {tj}
n
7) MINSLK: Minimum (total) slack
n
8) LFS: Minimum (total) slack per successor
n
9) ACTIMj: (Greatest) time from start of task j to end of project = CP - LSj
n
10) ACTRESj: (max) (ACTIMj)
n
11) GENRESj: w ACTIMj + (1-w) ACTRESj where 0 ≤ w ≤ 1
• Rkj
k
• Rkj
k
• Rkj / tj
tj
k
Resource Allocation Problem #2
Start
Task A1
6 days
Task A2
4 days
Task B1
3 days
Task B2
5 days
Task C 1
2 days
Task C 2
5 days
Gold Crew
Purple Crew
End
How to schedule tasks to minimize project makespan?
Priority scheme: schedule tasks using total slack (i.e., tasks with
smaller total slack have higher priority)
Gol d C rew
Pu rpl e
C re w
Task A1
Task B1
1
2
3
4
5
6
7
1
2
3
4
5
6
7
8
Task C1
9
10
11
12
9
10
11
12
Task A2
8
13
14
15
16
17
15
16
17
Task B2
13
14
18
19
20
Task C2
18
19
20
Resource Allocation Example (cont’d)
But, can we do better? Is there a better priority scheme?
Gol d C rew
Pu rpl e
C re w
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Microsoft Project Solution (Resource Leveling Option)
Solution by: Microsoft Project 2000
Critical Chain Project Management
• Identify the critical chain: set of tasks that determine the overall
duration of the project
• Use deterministic CPM model with buffers to deal with uncertainty
• Remove padding from activity estimates (otherwise, slack will be
wasted). Estimate task durations at median.
• Place project buffer after last task to protect customer’s completion
schedule
• Exploit constraining resource(s)
• Avoid wasting slack times by encouraging early task completions
• Have project team focus 100% effort on critical tasks
• Work to your plan and avoid tampering
• Carefully monitor and communicate buffer status
Critical Chain Buffers
Project Buffer
: placed after last task in project to protect schedule
Feeding Buffers
: placed between a noncritical task and a critical task
when the noncritical task is an immediate predecessor of the critical task
Resource Buffers
resource type
: placed just before a critical task that uses a new
Critical Chain Illustrated
Feeding Buffers
Task C 1
2 days
Task B1
3 days
Task A1
6 days
End
Start
Task C 2
5 days
Resource Buffers
Task B2
5 days
Task A2
4 days
Non-Renewable Resources
12 units
Task B
5 wks
6 unit s
8 unit s
Task A
6 wks
START
Task D
2 wks
END
Task C
3 wks
10 units
Task
A
B
C
D
Du rati on
6
5
3
2
No. of Non re n ewabl e
Re s ou rces U ni ts
Ne e de d
Earl y S tart
6
0
12
6
10
6
8
11
Late S tart
0
6
8
11
Non-Renewable Resources: Graphical Solution
C u mu l ati ve Re sou rce s
S u ppl i ed
40
Cumulative Resources
36
32
C u mu l ati ve Re sou rce s
Re qu ire d
28
24
20
16
12
8
4
1
2
3
4
5
6
7
8
9
10
Weeks
11
12
13
14
15
16
17
18
19
20
Resource Allocation Problem #3
Issue: When is it better to “team” two or more
workers versus letting them work separately?
• Have 2 workers, Bob and Barb, and 4 tasks: A, B, C, D
• Bob and Barb can work as a team, or they can work separately
• When should workers be assigned to tasks? Which configuration
do you prefer?
How to Assign Project Teams?
A
C
Start
End
B
D
Configuration #1
Bob and Barb work jointly on all four tasks; assume that they can complete each
task in one-half the time needed if either did the tasks individually
Configuration #2
Bob and Barb work independently. Bob is assigned to tasks A and C; Barb is
assigned to tasks B and D
Bob and Barb: Configuration #1
TASK A
Durati on
6
5
4
Expected
durati on
Prob
0.33
0.33
0.33
5.0
TASK B
Durati on
9
6
Prob
0.667
0.333
TASK C
Durati on
12
7
8.0
Prob
0.6
0.4
TASK D
Durati on
10
6
10. 0
Configuration #1
Bob and Barb work jointly on all four tasks.
What is the expected project makespan?
Prob
0.25
0.75
7.0
Bob and Barb: Configuration #2
Bob and Barb work independently. Bob is assigned to tasks A and C; Barb is
assigned to tasks B and D
Realizat ion #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
A
6
6
6
6
6
6
6
6
5
5
5
5
5
5
5
5
4
4
4
4
4
4
4
4
B
9
9
9
9
6
6
6
6
9
9
9
9
6
6
6
6
9
9
9
9
6
6
6
6
C
12
12
7
7
12
12
7
7
12
12
7
7
12
12
7
7
12
12
7
7
12
12
7
7
D
10
6
10
6
10
6
10
6
10
6
10
6
10
6
10
6
10
6
10
6
10
6
10
6
Bob
A+ C
Barb
B+D
18
18
13
13
18
18
13
13
17
17
12
12
17
17
12
12
16
16
11
11
16
16
11
11
19
15
19
15
16
12
16
12
19
15
19
15
16
12
16
12
19
15
19
15
16
12
16
12
max
(A+C,
B+D)
19
18
19
15
18
18
16
13
19
17
19
15
17
17
16
12
19
16
19
15
16
16
16
12
Prob
0.03
0.10
0.02
0.07
0.02
0.05
0.01
0.03
0.03
0.10
0.02
0.07
0.02
0.05
0.01
0.03
0.03
0.10
0.02
0.07
0.02
0.05
0.01
0.03
Bob and Barb: Configuration #2
Bob and Barb work independently. Bob is assigned to tasks A and C; Barb is
assigned to tasks B and D
max (A+C,
B+D)
12
13
15
16
17
18
19
Prob
0.07
0.03
0.20
0.20
0.17
0.17
0.17
Cumulati ve
Prob
0.07
0.10
0.30
0.50
0.67
0.83
1.00
Expected Project Makespan: 16.42
Parallel Tasks with Random Durations
Task A
START
END
Task B
• Assume that both Tasks A and B have possible durations:
8 days with probability = 0.5
10 days with probability = 0.5
• What is expected duration of project? (Is it 9 days?)
Project Monitoring and Control
n
“It is of the highest importance in
the art of detection to be able to
recognize, out of a number of acts,
which are incidental and which are
vital. Otherwise your energy and
attention must be dissipated instead
of being concentrated.”
Sherlock Holmes
Status Reporting?
One day my Boss asked me to submit a status
report to him concerning a project I was working
on. I asked him if tomorrow would be soon enough.
He said, "If I wanted it tomorrow, I would have
waited until tomorrow to ask for it!"
New business manager, Hallmark Greeting Cards
Control System Issues
n
n
n
n
n
What are appropriate performance metrics?
What data should be used to estimate the value of each
performance metric?
How should data be collected? From which sources? At
what frequency?
How should data be analyzed to detect current and future
deviations?
How should results of the analysis be reported? To whom?
How often?
Controlling Project Risks
Key issues to control risk during projecct:
(1) what is optimal review frequency, and
(2) what are appropriate review acceptance levels
at each stage?
“Both over-managed and under-managed
development processes result in lengthy design
lead time and high development costs.”
Ahmadi & Wang. “Managing Development Risk in
Product Design Processes”, 1999
Project Control & System Variation
Common cause variation: “in-control” or normal
variation
Special cause variation: variation caused by forces
that are outside of the system
According to Deming:
• Treating common cause variation as if it were special cause variation
is called “tampering”
• Tampering always degrades the performance of a system
Control System Example #1
n
Project plan: We estimate that a task will
take 4 weeks and require
n
1600 worker-hours
At the end of Week 1, 420 worker-hours
have been used
Is the task “out of control”?
Control System Example (cont’d)
Week 2: Task expenses = 460 worker-hours
Planned Cost
Week
(BCWS)
1
400
2
400
Actual Cost
420
460
Cumulative
Actual Cost
(ACWP)
420
880
470
Cost (in worker-hours)
460
450
440
430
420
410
400
390
380
370
1
2
3
4
W ee k
Is the task “out of control”?
Control System Example (cont’d)
Week 3: Task expenses = 500 worker-hrs
W ee k
Plan n e d cost
(work e r-h ou rs )
Actu al cos t
(work e r-h ou rs )
1
2
3
400
400
400
420
460
500
C u mu l ati ve cos t
(work e r-h ou rs )
420
880
1380
600
Worker-hours
500
400
300
200
100
0
1
2
3
4
W ee k
Is the task “out of control”?
Earned Value Analysis
• Integrates cost, schedule, and work performed
• Based on three metrics that are used as the basic
building blocks:
BCWS: Budgeted cost of work scheduled
ACWP: Actual cost of work performed
BCWP: Budgeted cost of work performed
Schedule Variance (SV)
Schedule Variance (SV) = difference between value of
work completed and value of scheduled work
Schedule Variance (SV) = Earned Value - Planned Value
= BCWP - BCWS
Cost Variance (CV)
Cost Variance (CV) = difference between value of
work completed and actual
expenditures
Cost Variance (CV) = Earned Value - Actual Cost
= BCWP - ACWP
Earned Values Metrics Illustrated
Worker-Hours
Present time
Planned Value
(BCWS)
Actual Cost
(ACWP)
BAC
Cost Variance
(CV)
Earned Value
(BCWP)
Schedule Variance
(SV)
Week 1
Week 2
Week 3
Week 4
Week 5
Week 6
Relative Measure: Schedule Index
Schedule Index
(SI) =
BCWP
BCWS
If SI = 1,
then task is on schedule
If SI > 1,
then task is ahead of schedule
If SI < 1,
then task is behind schedule
Relative Measure: Cost Index
Cost Index (CI) =
BCWP
ACWP
If CI = 1,
then work completed equals
payments (actual expenditures)
If CI > 1,
then work completed is ahead
of payments
If CI < 1,
then work completed is behind
payments (cost overrun)
Example #2
W E E K
1
2
3
4
5
6
7
8
9
10
Task A (36 work e r-h rs)
6
6
6
8
10
Task B (36 work e r-h rs)
12
12
12
Task C (56 work e r-h rs)
10
10
12
12
12
Weekly
Scheduled
Worker-Hrs
Cumulative
6
6
6
20
22
22
10
12
12
12
Scheduled
Worker-Hrs
(BCW S)
6
12
18
38
60
82
92
104
116
128
Example #2 (cont’d)
Progress report at the end of week #5:
Cumulative Percent of Work Completed:
Week
Task A
Task B
Task C
1
2
3
4
5
15%
30%
40%
60%
80%
25%
65%
Not st art ed yet
Worker-Hours Charged to Project:
Week
1
2
3
4
5
Task A
Task B
Task C
5
6
8
10
15
Not st art ed yet
10
10
Example #2 (cont’d)
Progress report at the end of week #5:
W E E K
1
2
3
4
5
6
7
8
9
10
6
12
18
38
60
82
92
104
116
128
5
11
19
44
64
Earn e d Val u e
(BC WP)
5.4
10.8
14.4
30.6
52.2
S ch edu l e
Varian ce (S V)
-0.6
-1.2
-3.6
-7.4
-7.8
C os t Vari an ce
(C V)
0.4
-0.2
-4.6
-13.4
-11.8
C u mu l ati ve
S ch edu l ed
W ork e r-Hrs
(BC WS )
Actu al W ork e rHrs Us ed
(AC WP)
Example #2 (cont’d)
140
BAC
120
BC W S
Performance Metric
100
80
C os t
Varian ce
S ch edu l e
Varian ce
60
AC W P
40
BC W P
20
0
1
2
3
4
5
6
W ee k
7
8
9
10
Using a Fixed 20/80 Rule
Cumulative Percent of Work Completed:
Week
Task A
Task B
Task C
1
2
3
4
20%
20%
20%
5
20%
20%
Not st art ed yet
20%
20%
W E E K
1
C u mu l ati ve
S ch edu l ed
W ork e r-Hrs
(BC WS )
6
Actu al W ork e rHrs Us ed
(AC WP)
5
Earn e d Val u e
(BC WP)
7.2
S ch edu l e
Varian ce (S V) 1.2
C os t Vari an ce
(C V)
2.2
2
3
4
5
6
7
8
9
10
12
18
38
60
82
92
104
116
128
11
19
44
64
7.2
7.2
14.4
14.4
-4.8
-10.8
-23.6
-45.6
-3.8
-11.8
-29.6
-49.6
Using a Fixed 20/80 Rule
140
120
Cost (in Worker-hours)
100
80
BC W S
AC W P
60
40
BC W P
20
0
1
2
3
4
5
6
Week
7
8
9
10
Updating Forecasts: Pessimistic Viewpoint
Assumes that rate of cost overrun will continue
for life of project….
Estimate at Completion(EAC) = ACWP BAC = 1 BAC .
BCWP
CI
= (64/52.2) 128 = 1.23 x 128 = 156.94 worker-hrs
Updating Forecasts: Optimistic Viewpoint
Assumes that cost overrun experienced to date
will cease and no further cost overruns will be
experienced for remainder of project life…
Estimate at Completion
(EAC) = BAC - CV = 128 + 11.8 = 139.8 worker -hrs .
Multi-tasking with Multiple Projects
How to prioritize your work when you have multiple
projects and goals?
Consider two projects with and without multi-tasking
Project A
A-1
B-1
Project B
A-2
B-2
A-3
B-3
A-4
B-4
Due-Date Assignment with Dynamic Multiple Projects
• Projects arrive dynamically (common situation for both
manufacturing and service organizations)
• How to set completion (promise) date for new projects?
• Firms may have complete control over due-dates or only partial
control (i.e., some due dates are set by external sources)
• How to allocate resources among competing projects and tasks (so
that due dates can be realized)?
• What are appropriate metrics for evaluating various rules?
What Does the Research Tell Us?
• Study by Dumond and Mabert* investigated four due date assignment
rules and five scheduling heuristics
• Simulated 250 projects that randomly arrive over 2000 days
• average interarrival time = 8 days
• 6 - 49 tasks per project (average = 24); 1 - 3 resource types
• average critical path = 31.4 days (range from 8 to 78 days)
• Performance criteria: 1) mean completion time
2) mean project lateness
3) standard deviation of lateness
4) total tardiness of all projects
• Partial and complete control on setting due dates
* Dumond, J. and V. Mabert. “Evaluating Project Scheduling and Due Date Assignment Procedures:
An Experimental Analysis” Management Science, Vol 34, No 1 (1988), pp 101-118.
Experimental Results
• No one scheduling heuristic performs best across all due date
setting combinations
• Mean completion times for all scheduling and due date rules not
significantly different
• FCFS scheduling rules increase total tardiness
• SPT-related rules do not work well in PM (SASP)
• Best to use more detailed information to establish due dates
Project Management Maturity Models
• Methodologies to assess your organization’s current level of
PM capabilities
• Based on extensive empirical research that defines “best
practice” database as well as plan for improving PM process
• Process of improvement describes the PM process from
“ineffective” to “optimized”
• Also known as “Capability Maturity Models”
PM Maturity Model Example*
1)
Ad-Hoc
The project management process is described as disorganized, and occasionally even
chaotic. Systems and processes are not defined. Project success depends on individual effort.
Chronic cost and schedule problems.
2)
Abbreviated: Some project management processes are established to track cost, schedule,
and performance. Underlying disciplines, however, are not well understood or consistently
followed. Project success is largely unpredictable and cost and schedule problems are the norm.
3)
Organized: Project management processes and systems are documented, standardized, and
integrated into an end-to-end process for the company. Project success is more predictable. Cost
and schedule performance is improved.
4) Managed: Detailed measures of the effectiveness of project management are collected and used
by management. The process is understood and controlled. Project success is more uniform.
Cost and schedule performance conforms to plan.
5) Adaptive:
Continuous improvement of the project management process is enabled by feedback
from the process and from piloting innovative ideas and technologies. Project success is the
norm. Cost and schedule performance is continuously improving.
* source: The Project Management Institute PM Network (July, 1997), Micro Frame Technologies, Inc. and
Project Management Technologies, Inc. (http://pm32.hypermart.net/)