2 project scheduling
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Project Scheduling and HR Planning
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Network Diagram
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A network diagram is a sequence of steps (activities) thatare linked together in the logical sequence they need to
be carried out.
Provides the project team a consensus of understanding
of how the project should be implemented Planning should not be done alone, it's a group activity,
Boosts efficiency of understanding and communication
Facilitates important buy-in from the whole Project Team.
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Example: Network Diagram
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No looping back is alloweddeal with iterations
by hiding them within single activities
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Types of activity dependency
4
Finish to start (FS) The following activity starts when the previous one has been
finished
Default type of dependency (e.g. in MS Project)
Software
development Acceptance testing
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Start to start (SS) When one activity starts another has to start as well
Finish to finish (FF)
when one activity finishes the other must finish too
Test prototype
Document
Amendments
1 day 2 days
SS FF
You could use these with lags.
E.g. documentation of the changes to the
prototype starts 1 day after the testing and
finishes 2 days after testing has been completed
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Start to finish (SF) An activity will end when another activity starts
Operate temporarysystem
Acceptance testof new system
Cutover to newsystem
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Nature of dependency
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Mandatory dependency Inherent in the nature of work to be performed on a project
Relationship is unavoidable
E.g. You cannot hold a training class until the training materials
are ready Discretionary dependency
Defined by the project team
E.g. The project team follow good practice and does not start
detailed design work until stakeholders sign off on all theanalysis work
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External dependency Relationship between project and non-project activities
E.g. Installation of new software might depend on delivery of
new hardware from external supplier
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Critical path method (CPM)
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The critical path method (CPM), is a mathematically basedalgorithm for scheduling a set of project activities.
A critical path for a project is the series of activitiesthat determines the earliest time by which the project canbe completed
Forward pass
How early can we complete this project?
Backward pass
How late can we start any activity without delaying theproject?
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Start and finish times
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Earliest start (ES)
Latest start
= LF - duration
Latest Finish (LF)
= latest task can be completed
without affecting project end time
Earliest finish (EF)
= ES +duration
activity
Earliest start = day 5
Latest finish = day 30
Duration = 10 days
Earliest finish = ?
Latest start = ?
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Activities
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Activity label, activity description
DurationEarlieststart
Earliestfinish
Latest
startLatest
finishTotal Float
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Forward pass
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Start at beginning (Day 0) and work forward Earliest start date for the current activity = earliest finish
date for the previous
When there is more than one previous activity, take the latest
earliest finish
EF = day 7
ES = day 7
EF = day10
ES = day10
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0 6 6 9
0 4 4 8
0 10 4 7
9 11
10 13
How early can the project be completed?
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Backward pass
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Start from the last activity and work backwards
Latest finish for current activity = Latest start for the
following activity
More than one following activity - take the earliest LS Latest start (LS) = LF for activity - duration
LS = day 7LF = day 7
LS = day 6
LF = day 6
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0 6 6 9
0 4 4 8
0 10 4 7
9 11
10 13
2 8 8 11
3 7 7 11
0 10 7 10
11 13
10 13
How late can we start any activity without
delaying the project?
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Total float (Total Slack)
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Represents the amount of time an activity can be delayed
without delaying the project.
Total float = LF - ES - duration or LS- ES or LF-EF
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Example: Total float
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0 6 6 9
0 4 4 8
0 10 4 7
9 11
10 13
2 8 8 11
3 7 7 11
0 10 7 10
11 13
10 13
2
3
0
2
3
3
2
0
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Critical path
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Any delay in an activity on the critical path will delaywhole project
Methods to find the critical path
Find the longest path through the network diagram
Calculate total float for each activity on the WBS using anetwork diagram. Critical path is the one with all activities
with 0 floats
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Example: critical path
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0 6 6 9
0 4 4 8
0 10 4 7
9 11
10 13
2 8 8 11
3 7 7 11
0 10 7 10
11 13
10 13
2
3
0
2
3
3
2
0
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More about critical paths
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If one of more activities on the critical path takes longerthan planned, the whole project schedule will slip unlesscorrective action is taken
The critical path may change as you enter actual start andfinish dates during project execution
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Free float (Free Slack)
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The time an activity can be delayed without affectingany other activity.
Free Float = ES for following activity - EF for the
current activity
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Free float: example
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Consider activity D. The starting date can be delayed 3 weeks without
affecting the project end day.
However, the start date of H will be affected
(4+3+4=11).
6 9
4 8 9 11
8 11
7 11 11 13
2
3 2
The free float for activity D
= 9 - 8 = 1.
D can only be delayed for up to 1 day without
affecting H.
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CPM vs PERT
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CPM is for repeated projects Assume an accurate estimate of duration activity
PERT - "Project Evaluation and Review Technique"
Risk-based approach for duration estimation
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Estimation in activity duration
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Pessimistic time = 10 daysOptimistic time = 4 days
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Three-point estimating in PERT
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Most likely time (m), Optimistic time (a),Pessimistic (b)
Expected activity duration
te = (a + 4m +b) / 6
Standard deviation of activity duration s = (b-a)/6
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Example
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Joe, a network engineer, has been asked to give a timeestimate for setup of a new Cisco switch that he has
never worked with before.
How long will it take for Joe to configure, test, and
deploy the switch?
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The last time he did something similar with an earlier model of
Cisco switch, it took him a total of 40 hours, so Joe assigned a
most likely estimate of 40 hours.
But now that Joe has done it once and he expects this process
to be similar, he might be able to get it done faster, so Joe's
optimistic estimate is 20 hours.
But recently Joe read an article stating that Cisco had
completely changed the configuration module for this upgrade,
so it may take longer than it did last time; Joe therefore assigns
a pessimistic estimate of 56 hours.
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Example
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What is the expected project duration?
What is the standard deviation for expected project duration?
Task a m b te s
A 10 12 16
B 8 10 14
C 20 24 38
Task A
Task B
Task C
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Task A
Task B
Task a m b te s
A 10 12 16 12.66 1
B 8 10 14 10.33 1
C 20 24 38 25.66 3
Task C
Critical path = (A, C)
Expected end time = 12.66+25.66 = 38.32
Std dev (Expected end time) = sqrt (12+32) = 3.16
E(A+B) = E(A) + E(B)
V(A+B) = V(A) + V(B) + COV(A,B)
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Likelihood of meeting a target
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Expected end time = 38.32 Assume the day-of completion follows the normal
distribution (Why?)
The chance of project completion by this time is 50%
38.32
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Table of Normal Distribution
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Assessing the likelihood
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Say the project deadline is 42 days
What is the probability that of completing the project by
the deadline?
z = (T te)/s
= (42-38.32)/3.16
= 1.164
The deadline is 1 standard
deviation above the expected
duration 38.82 42
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Graph of z values
Note: The STANDARDIZE calculation in Excel can be used to calculate the Z value.
Probability of meeting the deadline is 100-15% = 85%
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Schedule development
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Uses the results of the other time management processes
(activity definition, sequencing, estimating) to determine the
start and end date of the project
Determines the planned start and completion dates for each
activity listed on the WBS.
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Gantt chart
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A type of bar chart that illustrates a project schedule
Activity network with start and end days
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Project milestones
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Significant important events on a project
E.g. Sign-off of key documents, completion of specific products,
completion of important process-related work (e.g. awarding a
contract to supplier)
Often used by project sponsors or senior managers to
assess and monitor the project progress
No cost or duration is associated with a milestone
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Major milestones
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The major milestones give
visibly or progress to
people external to the
project.
E.g. project sponsors and
customers.
Milestone Milestone Goal
Concept approval
Feasibility studies and basic system concepts
have been approved by management and the
project is authorized to proceed to detailedrequirements definition.
Requirements review
Requirements specifications are complete,
correct, approved and suitable for input to
design.
Preliminary design review
The architectural design satisfies all product
requirements, is approved and is suitable for
input into the detailed design process.
Critical design review
Detailed designs fully implement the system
architecture, are approved and are suitable for
input into the development of code.
Test plan review
Test plans are adequate for the testing of all
product features, are approved and are suitable
for input to the development of test cases and
test procedures.
Test readiness review
Developed and unit tested software has been
passed by the test team and is suitable for input
into integration testing.
System test reviewThe software product has passed systemtesting and is suitable for input into acceptance
testing.
Operational readiness review
The software product has passed acceptance
testing and is suitable for deployment in its
target production environment.
Product operationalThe software is in use in its target operational
environment.
http://www.chambers.com.au/glossary/milestone.php
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Minor milestones
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Minor milestones are the
monitoring points you as
project manager use to
maintain control of day to
day activities.
Give the team a sense of
achievement by
demonstrating progress on
a daily or weekly basis
Milestone Milestone Goal
Document outline complete
A document outline has been
produced describing the format,
content and objectives of each
major section of a largedocument.
Document complete
A document such as an Software
Requirements Specification has
passed peer review.
Technical investigation complete
The investigation of a technical
issue is complete and a summary
of the main issues and conclusions
has been presented and approved.
Compile completeA program compiles without
errors.
Software module completeA small program or function has
been completed and unit tested.
Software product build complete
The software product (or one of
its components) has been built an
it runs (not necessarily without
errors).
Test case complete
A small unit of testing has been
completed and test results
recorded.
Bug fix complete
A bug identified in a Software
Anomaly Report (SAR) has been
fixed and the SAR closed out.
T h i f h i j
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Techniques for shortening a project
schedule (schedule analysis)
Knowing the critical path helps you make schedule trade-offs
Techniques
Replace a team member with a more skilled person
Shortening durations of critical tasks by changing their scope Delay tasks with positive float and move resource to work
with tasks on critical path.
Crashing
Fast tracking
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Crashing
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For each task in the critical path, look for the task that
could be done faster if more resources were added.
Goal:
Look for the task that would deliver the most compression for
the least incremental cost
C hi th h d l S ft
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Crashing the schedule: Software
development example
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Duration =Work
Resource unit
Duration is
shortened by 1
day
Add 1 more programmer
to task 11
Effort driven:
As resources are added to or removed froma task, the task duration is adjusted but the
total work on the task stays the same.
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Fast tracking
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Look for activities in the critical path that can be done in
parallel
May involve the need to add more resources
To perform two tasks in parallel, the input of one task
should not depend on the output of another task
F t t ki S ft d l t
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Fast tracking: Software development
example
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Design and code can be performed in parallel
Wh t if f d i d di i
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What if we perform design and coding in
parallel?
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Human Resource Management Planning
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Team building activities
Keeping team members motivated
Reward/Recognition
Tangible (e.g. cash, gifts)
Intangible (e.g. praise, favorably mention in monthly report or meetings, training)
Training Acquire the skills required for the project
When people feel that theyre growing professionally, they stay more involved
and get more excited by their work.
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Staffing Management Plan
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Allocating individuals to activities
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Factors Availability - who is free?
Criticality - put more experienced, safer, staff on the criticalactivities
Risk
Training - by allocating challenging tasks to relativelyinexperienced staff
Based on the capability of the resource and the effort, wecan create duration/time estimates for each activity
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References
Information Technology Project Management, 7th Edition
Chapter 6