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Transcript of Project Time Management - IS331is331.yolasite.com/resources/ch06.pdfensure timely completion of a...
Project Time Management
Understand the importance of project schedules and good
project time management.
Define activities as the basis for developing project
schedules.
Describe how project managers use network diagrams and
dependencies to assist in activity sequencing.
Understand the process of sequencing activities and the four
types of activity dependencies
Use Gantt chart for planning schedule information.
Describe how software can assist in project time management.
Project time management involves the processes required to
ensure timely completion of a project.
Project time management describes the processes and
methods required to create and manage appropriate schedules
to complete the project.
1. Defining Activities– identifies the lowest level of work on
the WBS, “work packages”, that needs to be performed to
create the finished product deliverable.
2. Sequencing Activities – identifying and documenting the
relationships between project activities.
3. Estimating activity resources: estimating how many
resources (people, equipment, materials) a project team
should use to perform project activities.
4. Estimating activity durations: estimating the number of
work periods that are needed to complete individual
activities.
5. Developing the schedule: analyzing activity sequences,
activity resource estimates, and activity duration estimates
to create the project schedule.
6. Controlling the schedule: involves controlling and
managing changes to the project schedule.
An activity or task is an element of work normally found on
the work breakdown structure (WBS) that has an expected
duration, cost, and resource requirements.
Activity definition involves developing a more detailed WBS
and supporting explanations to understand all the work to be
done so you can develop realistic cost and duration estimates.
The goal of the defining activities is to ensure that the project
team has complete understanding of all the work they must do
as part of the project.
Depending on the technique used to create the WBS (refer to
chapter 5), typically the work packages are built by
decomposing parent activities down into smaller and smaller
units of work.
The 100% rule is in affect; all of the work packages defined
must add up to 100% of the total scope of the project .
Not all of the work packages will be defined at the same level
of detail.
The main outputs of this process are:
Activity list: is a tabulation of activities to be included on a
project schedule. The list should include the activity name,
an activity number, and a brief description of the activity.
Activity attributes: provide more schedule-related
information about each activity.
Milestone list: is a significant event that normally has no
duration.
Sequencing activities means determining the dependencies, or relationships between project activities or tasks.
There are three basic reasons for creating dependencies:
◦ Mandatory dependencies: inherent in the nature of the work being performed on a project. Ex. write software and then test.
◦ Discretionary dependencies: defined by the project team offer the most flexibility;
◦ External dependencies: involves the relationships between project and non-project activities.
You must determine correct dependencies to create a realistic schedule.
Network diagram is a tool that can be used to showing activity sequencing;
Network diagrams: is a schematic display of the logical relationships among, or sequencing of, project activities.
Network diagram represents activities that must be done to complete the project.
Network diagram has two main formats:
1. Arrow Diagramming Method (ADM)
2. Precedence Diagramming Method (PDM)
1. Arrow Diagramming Method (ADM)
Also called activity-on-arrow (AOA) network diagrams.
Consists of :
Lines with arrows that represent activities .
Nodes or circles which represent the starting and ending
points of activities.
Key Drawback: Can only show finish-to-start dependencies
• Lines with arrows represent tasks.
• Circles with words or numbers represent the begin or end of a
task.
1. You draw the first Begin circle or node and then proceed with the tasks that
do not have a predecessor, usually the first tasks to be done on the project.
These are shown in the diagram as lines A, K, and F.
2. Then you move to the next tasks listed in the WBS in order of precedence.
Activity B has a predecessor of A and Activity C has a predecessor of B and
so on. Tasks M, G, and L have no successors so we draw their arrows to the
End node.
3. You add circles at the end of each arrow as an end point. At the end of the
process you then number each circle.
4. Be prepared as you draw this diagram to draw and then erase and redraw as
you work your way down the task list.
2. Precedence Diagramming Method (PDM)
Consists of:
Boxes that represent activities.
Arrows that show relationships between activities.
More popular than ADM method and used by project
management software
Better at showing different types of dependencies.
Activity Dependency Types:
Finish-to-start [FS] Finish coding module before unit testing.
Start-to-start[SS] On several IT projects, a group of activities all start
simultaneously, such as the many tasks that occur when a new system goes live.
Finish-to-Finish[FF] Quality control efforts cannot finish before production
finishes. Start-to-Finish[SF] Phase out legacy system can’t finish until x days after new
system starts acceptance testing.
Samples of Activity Dependency Types in Microsoft Project:
The task names are for this example shortened to just letters.
The lines with arrows are not labeled.
Notice that some of the activities (C, F, G, and H) have more
than one predecessor; some only have a successor (Begin) and
some only have a predecessor (End).
Before estimating activity durations, you must have a good idea of the quantity and type of resources that will be assigned to each activity.
Resources are people, equipment, and materials
Consider important issues in estimating resources:
◦ How difficult/complex will it be to complete specific activities on this project?
◦ What is the organization’s history in doing similar activities?
◦ Are the required resources available? Internal or External?
◦ Very important to match the right person with the right task!
The main outputs of the resource estimating process:
List of activity resource requirements.
Project document updates.
A resource breakdown structure.
A resource breakdown structure: is a hierarchical structure
that identifies the project’s resources by category and type.
Resource categories may include:
◦ analysts
◦ programmers
◦ testers
Programmers type may include:
◦ COBOL programmers
◦ Java programmers
After defining activities, determining their sequence, assigning
appropriate resources, the next step in time management is
duration estimating.
Duration includes the actual amount of time worked on an
activity plus elapsed time.
Effort is the number of workdays or work hours required to
complete a task.
People doing the work should help create estimates, and an
expert should review them.
Duration estimate may be given as:
◦ Discrete numbers (2 weeks).
◦ Ranges (3 to 5 weeks).
◦ Three-point estimate.
Three-point estimate is an estimate that includes an
optimistic, most likely, and pessimistic estimate, such as:
three weeks for the optimistic,
four weeks for the most likely,
and five weeks for the pessimistic estimate.
Uses results of the other time management processes (activity
definition, sequencing, estimating) to determine the start and
end date of the project.
Also determines the planned start and completion dates for
each activity listed on the WBS. The deliverable from this
process is the project schedule.
Tools used for schedule development:
◦ Gantt chart.
◦ Critical path method.
◦ PERT.
◦ Critical Chain scheduling.
1. 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.
Symbols include:
◦ Black diamonds: milestones .
◦ Thick black bars: summary tasks.
◦ Lighter horizontal bars: durations of tasks.
◦ Arrows: dependencies between tasks.
2. Critical Path Method CPM is a network diagramming
technique used to predict total project duration.
CPM uses the sequence and duration of activities to determine
the 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.
Slack or float is the amount of time an activity may be
delayed without delaying a succeeding activity or the project
finish date.
Produces two key pieces of information:
1. The amount of slack , float for each activity in the
schedule.
2. The longest path through the schedule or said in another
way the shortest time the project can be completed
referred to as the critical path.
All activities that fall on this path are referred to as critical
path activities.
Calculating the Critical Path:
1. Calculate slack for each activity on the WBS using a
network diagram.
2. Find the longest path through the network diagram.
Begin
1 3 6
2
4
5
7
A
D
E
G
K
F
I
J
C
B LEnd
H2
5
4
5
2
1
7
3
8
3
9
4
(0,2)
(2,7)
(2,7)
(0,2) (5,6)
(7,9)
(7,9)(9,18)
(2,6)
(0,4)
(3,8)
(0,5)
(5,12)
(8,15) (15,18)
(12,15)
(4,7)(6,9)
(9,18)
(10,18) (18,22)
(18,22)(4,12)
(2,3)
Find the Longest Path:
Path 1 = A, D, G, K, L = 22 days
Path 2 = A, E, H, K, L = 19
Path 3 = A, E, I, L = 15
Path 4 = B, H, K, L = 20
Path 5 = B, I, L = 16
Path 6 = C, F, J, L = 19
Path 1 [ A,D,G,K,L ] is the critical path duration, because it
is the longest path.
Techniques for Shortening a Project Schedule (Schedule
Analysis) knowing the critical path helps project manager to
make schedule trade-offs:
Shortening durations of critical tasks by adding more
resources or changing their scope.
Project time shortening techniques:
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.
3. Critical Chain Scheduling is a method of scheduling that
considers limited resources when creating a project schedule
and includes buffers to protect the project completion date
unlike CPM which is only based on time.
Availability of scarce (rare) resources:
◦ Two tasks are planned to occur simultaneously.
◦ A single piece of equipment is available.
◦ Equipment is needed full time to complete each task.
Critical chain scheduling suggests:
◦ Delay one task until the equipment is available (sequential).
◦ Find another piece of equipment in order to meet the schedule
(parallel).
Multitasking occurs when a resource works on more than one
task at a time.
Critical chain scheduling attempts to minimize multitasking.
Multitasking disadvantages:
◦ can delay task completions.
◦ often involves wasted setup time, which increases total
duration.
Three tasks without multitasking:
Three tasks with multitasking:
In traditional estimates, people often add a buffer ( additional
time to complete a task) and use it if it’s needed or not.
Critical chain schedule removes buffers from individual
tasks and instead creates:
1. A project buffer, which is additional time added before the
project’s due date.
2. Feeding buffers, which is additional time added before
tasks on the critical path.
4. Program Evaluation and Review Technique (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-duration estimates
based on using optimistic, most likely, and pessimistic
estimates of activity durations, or a three-point estimate.
PERT weighted average =
optimistic time + 4* most likely time + pessimistic time
6
Example: optimistic time = 8 days, most likely time = 10 days, and pessimistic time = 24 days
PERT weighted average =
8 workdays + 4 * 10 workdays + 24 workdays = 12 days 6
Therefore, you’d use 12 days on the network diagram instead of
10 when using PERT for the above example.
The main advantage of PERT is that it attempt to
address the risk associated with duration estimates.
The PERT weighted averages for each activity are
added to the network diagram to show the start dates
and finish dates for each and the final project end date.
The goal of schedule control is to know the status of the
schedule, influence the factors that cause schedule changes,
determine that the schedule has changed, and manage changes
when occur.
Word-processing software.
Spreadsheets help to perform financial calculations.
Communication software.
Project management software.
Decision support models.
Project time management includes the processes required to
ensure timely completion of a project.
Main processes include:
Defining activities.
Sequencing activities.
Estimating activity resources.
Estimating activity durations.
Developing the schedule.
Controlling the schedule.