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ELC 347. DAY 8. Agenda. Questions Assignment 3 Corrected 4 A’s , One non-submit Assignment #4 Due Capstone Proposal Due Group Progress report due Exam 2 Slight Change 10 M/C (5 points each) 5 essays (10 points each) 1 hour 15 minutes Open book, Open Notes - PowerPoint PPT Presentation
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ELC 347
DAY 8
Agenda
Questions Assignment 3 Corrected
4 A’s , One non-submit Assignment #4 Due Capstone Proposal Due Group Progress report due Exam 2
Slight Change 10 M/C (5 points each) 5 essays (10 points each) 1 hour 15 minutes Open book, Open Notes
Ghattas 4-8, Project 8-10 Group Project Meeting (30 Min) Discussion on Network Analysis and Duration Estimating
Network Analysis and Duration Estimating
Laying the Groundwork for Commitment
Setting Duration Estimates Determining the critical Path Meeting external deadlines
Groundwork for commitment
Ask the people that actually doing the work
If more than one is capable ask the one with the most experience
Be realistic Be an advocate for your team
Duration Estimating
Duration – the elapsed time from the start of an activity until it is finished
Effort -- the actual time spent on the project Example
Tony work on a project task for 20 hours at 4 hours per day starting Monday mourning. The project task was completed Late Friday Effort – 20 hours Duration – 5 days
Techniques for Estimating Duration
Experience Historical data Research Modeling Experiments Breakdown/roll-up
Delphi Method Panel of experts
Consultants Three outside
Estimates Ranging Other techniques
Special Cases (Out of your hands)
Inspections Deliveries Breakdowns and repairs Approvals
Normalizing Duration
Goal is most “cost-efficient” plan Determine the most cost-efficient
technical approach Make and estimate of long the most cost
efficient method will take to complete Selectively adjust you estimate for any
activity that is subject to common problems.
CPM versus PERT
PERT was developed by US Navy in the 1950s’
CPM was developed by Remington Rand and DuPont around the same time.
Only difference is in durations estimating Pert uses 3 cases Most optimistic, most
pessimistic and most likely and determines probability for each DoPo + DpOp +DePe = final duration
CPM use only the most likely duration
Calculating a Project Duration
Determine each activity and its predecessors
Determine an estimated duration for each activity
Find the “Critical Path” Add up the durations along the critical
path
Whats the “Critical Path”
The longest path based on precedence of activities and durations through a PERT/CPM network
It’s critical because Its combined length determines the length of the
project It has NO slack Delay of any activities on the critical path delays
the entire project
Finding the critical path
Use “forward pass” Calculations Each activity should have
EPS earliest possible Start time EPF earliest possible finish time DUR duration EPF = EPS + DUR
EPS DUR EPF
Activity
Example
3 4 7
A
7 5 12
B
Special Case
If an activity has more than one processor its EPS is set to the latest EPF of all its processors
3 4 7
A7 5 12
C0 5 5
B
An example of forward pass
0 0 0
Start
8 4 12
F
0 4 4
D
4 8 12
C
25
4 29
Finish
0 5 5
A
16
5 21
I
21
4 25
J
4 4 8
E
16
7 23
H
12
4 16
G
5 4 9
B
Backwards Pass
Use to calculate Slack LAS -> Latest start time LAF -> Latest finish time TS -> total slack
EPS DUR EPF
ActivityLAS TS LAF
An example of backward pass
0 0 0
Start
0 0 0
8 4 12
F
12
4 16
0 4 4
D
0 0 4
4 8 12
C
4 0 12
25
4 29
Finish
25
0 29
0 5 5
A
3 3 8
16
5 21
I
16
0 21
21
4 25
J
21
0 25
4 4 8
E
8 4 12
16
7 23
H
18
2 25
12
4 16
G
12 0 16
5 4 9
B
8 3 12
Examine Critical Path for Reality Check
Is the total duration typical? Are the durations of the CP activities
typical? Reexamine all CP activity durations Reexamine assumptions
Optimizing the plan
Would bringing more expert talent to bear on the project speed it up?
Are there changes we could make in the resource procurement process to shorten wait times?
Would round the clock scheduling shorten duration? Would more money motivate the team to work
faster? Would an organizational change speed things up? Do we think it will take this long just because it
always has, or are there other ways to so this, which we haven’t thought of yet, that would shrink the timetable?
3 Lines of defense
Relieve the critical path Sharpen your pencil Crash activities
Summary
Construct a CPM Estimate normal durations Do a forward pass Identify Critical Path Optional
Do a backward pass to identify slack times Conduct a reality check Optimize the plan
1st line of defense - relieve the critical path 2nd line of defense - sharpen your pencil 3rd line of defense - crash activities