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1 CS 501 Spring 2008
CS 501: Software Engineering
Lecture 4
Project Management
2 CS 501 Spring 2008
Administration
Projects
• Announcements by project teams
Quiz 1
• Quiz 1 is next Thursday. Information is posted on the web site.
Office hours
• No office hours on Tuesday, February 5.
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OS 360
The operating system for the IBM 360 was two years late.
Question: How does a project get two years behind schedule?
Answer: One day at a time!
Fred Brooks Jr., The Mythical Man Month
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The Aim of Project Management
To complete a project:
• On time
• On budget
• With required functionality
• To the satisfaction of the client
• Without exhausting the team
To provide visibility about the progress of a project
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Aspects of Project Management
Planning
• Outline schedule during feasibility study
• Detailed schedule at the beginning of a project or phase of a project
Progress tracking
• Regular comparison of progress against plan
Final analysis
• Analysis of project for improvements during next project
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Terminology
Deliverable
Work product that is provided to the customer (report, presentation, documentation, code, etc.)
Milestone
Completion of a specified set of activities (e.g., delivery of a deliverable, completion of a process step)
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Terminology
Activity
Part of a project that takes place over time (also known as a task).
Event
The end of a group of activities.
Dependency
An activity that cannot begin until some event is reached
Resource
Staff time, equipment, or other limited resources required by an activity.
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General Approach to Project Planning
Identify deliverables and milestones
Divide project into activities (tasks)
For each activity estimate:
• time to complete from when activity begins
• dependencies on events before beginning
• resource requirements
Build a model that uses this data to create a work-plan, including schedule, resource allocation, and flexibility
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Project Planning Methods
Critical Path Method, Gantt charts, Activity bar charts, etc.
• Build a work-plan from activity data.
• Display work-plan in graphical form.
Project planning software (e.g., Microsoft Project)
• Maintain a database of activities and related data
• Calculate and display schedules
• Provide progress reports
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A Simple Gantt Chart
Source: Microsoft using Excel
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Gantt Charts
• Dates run along the top (days, weeks or months).
• Each row represents an activity. Activities may be scheduled sequentially, in parallel or overlapping.
• The schedule for an activity is a horizontal bar. The left end marks the planned beginning of the task. The right end marks the expected end date.
• The chart may be updated by filling in each activity to a length proportional to the work accomplished.
• Progress to date can be compared with the plan by drawing a vertical line through the chart at the current date.
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A More Complex Gantt Chart
Source: SmartDraw
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Activity Graph
An activity (task)
A dummy activity (dependency)
An event
A milestone
A scheduling technique that emphasizes dependencies
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Example: Activity Graph for a Distance Learning Course
START
Edit 1
Script TV
Make TV
Edit 2
Prototype Software
WriteSoftware
DocumentSoftware
Plan TV
Plan 1
Write 1
Plan 2
Plan Software
Write 2
Typeset 1
Typeset 2
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Scheduling: Background
PERT
Program Evaluation and Review Technique introduced by the U.S. Navy in 1957 to support the development of its Polaris submarine missile program.
PERT/Time
Activity graph with three time estimates (shortest, most probable, longest) on each activity to compute schedules.
PERT/Cost
Added scheduling of resources (e.g., facilities, skilled people, etc.)
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Critical Path Method
Uses Activity Graph with single time estimate for each activity to estimate:
earliest start date -- every activity begins at first possible time
latest start date -- every activity begins at the last possible time
slack -- difference between the latest and earliest start dates
A standard method for managing large construction projects.
On big projects, activity graphs with more than 10,000 activities are common.
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Time Estimates for Activities (Weeks)
6
4
2
2
3
3
3
3
82
1 1
4
12
12
1
4
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Earliest Start Dates
6
4
2
2
3
3
3
3
82
11
4
12
12
1
4
0
1
12
12
4
17
19
23
5
2522
17
17
15
15
8
2023 24
All activities beginning at a given event have the same earliest start date.
Earliest start dates in red
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Latest Start Dates
6
4
2
2
3
3
3
3
82
11
4
12
12
1
11
12
14
13
15
20
23 24 25
4 22
0
17
17
10
1817
2019
Each event must be achieved by the date shown or the final date will not be met.
Latest start dates in blue
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Critical Path
0/0
1/11
12/12
12/14
4/13
15/15 17/17
17/17
17/17
19/20
22/23 23/24 25/25
Every activity on the critical path must begin on the earliest start date.
Critical path in orange
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Slack
0/0
1/11
17/17
23/24
1
22
12/12
12/14
4/13
15/15 17/17
17/17 19/20
22/23 25/25
4
8
123 2
312
4
4
3
3
6
1 1
Slack of activity = (latest start)end - (earliest start)begin - (time estimate)
10 10
00 0
0
00
9
9
2
2
23
11
11
5
Slack in purple
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Estimating the Time for an Activity
With experienced staff, estimating the actual time to carry out a single task is usually fairly accurate, but ...
The little bits and pieces are underestimated
• The time from almost "done" to completely "done" is much longer than anticipated. (There's just one thing to tidy up. I need to put the comments into better shape. I really should get rid of that patch.)
• The distractions are not planned for. (My system crashed and I decided to upgrade the software. My child's school was closed because of snow. I spent the day showing visitors around.)
Some things have to be done twice.
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Start-up Time
On a big project, the start-up time is typically three to six months:
• Personnel have to complete previous projects (fatigue) or be recruited.
• Hardware and software has to be acquired and installed.
• Staff have to learn new domain areas and software (slow while learning).
• Clients may not be ready.
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Final Analysis with Critical Path Method
Administrative computing department at Dartmouth used the Critical Path Method for implementation phase of major projects (plan developed after project was well-understood).
Experience: Elapsed time to complete projects was consistently 30% to 40% longer than predicted by model.
Analysis:
• Some tasks not anticipated (incomplete understanding)• Some tasks had to be redone (change of requirements, technical changes)• Key personnel were on many activities (schedule conflicts)• System ZZZ (non-billable hours)
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Adding Resources to Activity Graph or Gantt Chart
Each activity is labeled with resources, e.g.,
Number of people (e.g., 2 Java programmers)
Key personnel (e.g., chief system architect)
Equipment (e.g., 3 servers with specified software)
Facilities (e.g., video conference center)
Each resource is labeled with availability, e.g.,
Hiring and training
Vacations
Equipment availability
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Using Critical Path Method for Resources
Assume every activity begins at earliest start date:
In each time period, calculate:
resources required
resources available
Identify shortage / surplus resources
Adjust schedule
acquire extra staff (e.g., consultants)
rearrange schedule (e.g., change vacations)
change order of carrying out activities
The earlier that a problem is known, the easier it is to fix.
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Key Personnel: The Mythical Man Month
In computing, not all people are equal
• The best are at least 5 times more productive.• Some tasks are too difficult for everybody.
Adding more people adds communications complexity
• Some activities need a single mind.• Sometimes, the elapsed time for an activity can not be
shortened.
What happens to the project if a key person is sick or quits?
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The Project Manager
• Create and maintain the schedule.• Track progress against schedule.• Keep some slack in the schedule (minimize risk).• Continually make adjustments:
Start activities before previous activity completeSub-contract activitiesRenegotiate deliverables
• Keep senior management informed (visibility).
The project manager needs the support of the head of the development team and the confidence of the team members.
