Topic:
Project Time Management
IT Project Management
INSTRUCTOR,SHU LIU
HIT SCHOOL OF SOFTWARE
Fall 2005
All rights reserved
Project Time Management 2
Outline
Importance of Project Schedules
Project Time Management Process
Activity Definition
Activity sequencing
Activity duration estimating
Schedule development
Schedule control
IT Project Management
Project Time Management 3
Importance of Project Schedules
Managers often cite delivering projects on time as
one of their biggest challenges
Average time overrun from 1995 CHAOS report was
222%; improved to 63% in 2001 study
Time has the least amount of flexibility; it passes no
matter what
Schedule issues are the main reason for conflicts on
projects,especially during the second half of projects
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Conflict Intensity Over the Life of a Project
0,0 0
0,0 5
0,1 0
0,1 5
0,2 0
0,2 5
0,3 0
0,3 5
0,4 0
P r o j e ct
F o r m a t i o n
E a r l y P h a se s M i d d l e P h a se s E n d P h a se s
C
o
n
fl
i
ct
I
n
ten
si
ty
S ch e d u l e s
P r i o r i t i e s
M a n p o w e r
T e ch n i ca l o p i n i o n s
P r o ce d u r e s
C o st
P e r so n a l i t y co n f l i ct s
A v e r a ge
To t a l C on f l i c t
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Project Time Management Processes
Project time management involves the processes
required to ensure timely completion of a project,
Processes include:
Activity definition
Activity sequencing
Activity duration estimating
Schedule development
Schedule control
Project Time Management 6
Where Do Schedules Come From?
Defining Activities
Project schedules grow out of the basic document that
initiate a project
Project charter includes start and end dates and budget
information
Scope statement and WBS help define what will be done
Activity definition involves developing a more
detailed WBS and supporting explanations to
understand all the work to be done
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Activity Definition
Input
1,WBS
2,Scope Statement
3,Historical info.
4,Constraints
5,Assumptions
Output
1,All Activities
2,Detailed description
3,Revised WBS
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Activity Sequencing
Involves reviewing activities and determining
dependencies
Mandatory dependencies,inherent in the nature
of the work; hard logic
Discretionary dependencies,defined by the
project team; soft logic
External dependencies,involve relationships
between project and non-project activities
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Project Network Diagrams
Project network diagrams are the preferred
technique for showing activity sequencing
A project network diagram is a schematic
display of the logical relationships among,or
sequencing of,project activities
Arrow Diagramming Method (ADM)
Precedence Diagramming Method (PDM)
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Arrow Diagramming Method (ADM)
Also called activity-on-arrow (AOA)
project network diagrams
Activities are represented by arrows
Nodes or circles are the starting and ending
points of activities
1
2
3 4
5
A
B
C
D E
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Process for Creating AOA Diagrams
(1)
1,Find all of the activities that start at node 1,Draw their finish
nodes and draw arrows between node 1 and those finish
nodes,Put the activity letter or name and duration estimate
on the associated arrow
2,Continuing drawing the network diagram,working from left
to right,Look for bursts and merges,Bursts occur when a
single node is followed by two or more activities,A merge
occurs when two or more nodes precede a single node
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Process for Creating AOA Diagrams
(2)
3,Continue drawing the project network diagram until
all activities are included on the diagram that have
dependencies
4,As a rule of thumb,all arrowheads should face
toward the right,and no arrows should cross on an
AOA network diagram
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Sample Activity-on-Arrow (AOA)
Network Diagram for Project X
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Precedence Diagramming Method (PDM)
Activities are represented by boxes
Arrows show relationships between
activities
More popular than ADM method and used
by project management software
Better at showing different types of
dependencies
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Task Dependency Types
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Sample Precedence Diagramming Method (PDM)
Network Diagram for Project X
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Activity Duration Estimating
After defining activities and determining their
sequence,the next step in time management is
duration estimating
Duration includes the actual amount of time
worked on an activity plus elapsed time
People doing the work should help create
estimates,and an expert should review them
Project Time Management 18
Schedule Development
Schedule development uses results of the
other time management processes to
determine the start and end date of the project
and its activities
Ultimate goal is to create a realistic project
schedule that provides a basis for monitoring
project progress for the time dimension of the
project
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Schedule Development
Important tools and techniques include
Gantt charts
PERT analysis
critical path analysis
critical chain scheduling
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Gantt Charts
In 1917 Henry Gantt developed the famous
Gantt chart as a tool for scheduling work in
job shops
Gantt charts provide a standard format for
displaying project schedule information by
listing project activities and their
corresponding start and finish dates in a
calendar format
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Gantt Charts
Symbols include:
A black diamond,milestones or significant events
on a project with zero duration?
Thick black bars,summary tasks
Lighter horizontal bars,tasks
Arrows,dependencies between tasks
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Gantt Chart for Project X
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Gantt Chart for Software Launch Project
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Sample Tracking Gantt Chart
white diamond,slipped milestone
two bars,planned and actual times
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Gantt Charts
Advantages
The main advantage of using Gantt Charts is that they
provide a standard format for displaying planned and
actual project schedule information.
And they are easy to create and understand
Disadvantages
In Gantt Chart,the dependencies are not as clearly as in
project network diagrams.
Project Time Management 26
Program Evaluation and Review Technique
(PERT)
PERT is a network analysis technique used to
estimate project duration when there is a high
degree of uncertainty about the individual activity
duration estimates
PERT uses probabilistic time estimates based on
using optimistic,most likely,and pessimistic
estimates of activity durations
Project Time Management 27
PERT Formula and Example
PERT weighted average formula:
optimistic time + 4X most likely time + pessimistic time
6
Example:
PERT weighted average =
8 workdays + 4 X 10 workdays + 24 workdays = 12 days
6
where 8 = optimistic time,10 = most likely time,and 24 =
pessimistic time
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Critical Path Method (CPM)
CPM is a project network analysis technique used to predict
total project duration
A critical path for a project is the series of activities that
determines the earliest time by which the project can be
completed
The critical path is the longest path through the network
diagram and has the least amount of slack or float
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Finding the Critical Path
First develop a good project network
diagram
Add the durations for all activities on each
path through the project network diagram
The longest path is the critical path
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Simple Example of Determining the Critical Path
Consider the following project network
diagram,Assume all times are in days.
2 3
4
5
A = 2 B =5
C =2
D =7
1 6
F =2
E=1
s ta r t fi n i s h
a,How many paths are on this network diagram?
b,How long is each path?
c,Which is the critical path?
d,What is the shortest amount of time needed to complete this project?
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Determining the Critical Path for Project X
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Using Critical Path Analysis to Make
Schedule Trade-offs
Knowing the critical path helps you make schedule
trade-offs
Free slack or free float is the amount of time an
activity can be delayed without delaying the early
start of any immediately following activities
Total slack or total float is the amount of time an
activity may be delayed from its early start without
delaying the planned project finish date
Project Time Management 33
More on the Critical Path
If one of more activities on the critical path takes
longer than planned,the whole project schedule will
slip unless corrective action is taken
True or False:
The critical path is not the one with all the critical activities;
it only accounts for time
The critical path is the shortest path through the project
network diagram.
There can be more than one critical path if the lengths of
two or more paths are the same
The critical path can change as the project progresses
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Techniques for Shortening a Project Schedule
Shortening durations of critical tasks for
adding more resources or changing their
scope
Crashing tasks by obtaining the greatest
amount of schedule compression for the
least incremental cost
Fast tracking tasks by doing them in
parallel or overlapping them
Project Time Management 35
Importance of Updating Critical Path Data
It is important to update project schedule
information
The critical path may change as you enter
actual start and finish dates
If you know the project completion date
will slip,negotiate with the project sponsor
Project Time Management 36
Critical Chain Scheduling
Critical chain scheduling is a method of scheduling
that takes limited resources into account when
creating a project schedule and includes buffers to
protect the project completion date
Critical chain scheduling assumes resources do not
multitask because it often delays task completions
and increases total durations
Project Time Management 37
Multitasking Example
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Buffers and Critical Chain
A buffer is additional time to complete a task
In traditional estimates,people often add a buffer and
use it if it’s needed or not
Murphy’s Law states that if something can go wrong,
it will,
Parkinson’s Law states that work expands to fill the
time allowed.
Project Time Management 39
Buffers and Critical Chain
Critical chain schedule removes buffers from
individual tasks and instead creates
A project buffer,which is additional time
added before the project’s due date
Feeding buffers,which are addition time
added before tasks on the critical path
Project Time Management 40
Example of Critical Chain Scheduling
Project Time Management 41
Controlling Changes to the Project Schedule
Perform reality checks on schedules
Allow for contingencies
Don’t plan for everyone to work at 100%
capacity all the time
Hold progress meetings with stakeholders
and be clear and honest in communicating
schedule issues
Project Time Management 42
Working with People Issues
Strong leadership helps projects succeed
more than good PERT charts
Project managers should use
Empowerment
incentives
discipline
negotiation
Project Time Management 43
Project Time Management
Activity definition
Activity sequencing
Activity duration
estimating
Schedule development
Schedule control
All Activities
Project Network
Diagrams
Duration
Estimates
Gantt Chart
Change control
process
Project Time Management 44
Group Exercise
Exercise 2 on page 150
Enter the information from Exercise 2 in
Project 2002/2003.
Gantt Chart
Network Diagram
Project Time Management 45