Chapter - 6

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.

Objectives

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.

What is Project Time Management?

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.

Project Time Management Processes

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.

Project Time Management Processes (cont.)

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.

1. Defining Activities

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.

1. Defining Activities (cont.)

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.

1. Defining Activities (cont.)

2 .Sequencing Activities

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.

2 .Sequencing Activities

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)

2 .Sequencing Activities Network diagram

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

Arrow Diagramming Method (ADM) Sample

• Lines with arrows represent tasks.• Circles with words or numbers represent the begin or end of a

task.

Process for Creating ADM Diagrams

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.

Arrow Diagramming Method (ADM) Example

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.

2 .Sequencing Activities Network diagram

2 .Sequencing Activities Network diagram

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.

2. Sequencing Activities Network diagram

Samples of Activity Dependency Types in Microsoft Project:

Sample PDM Network Diagram

PDM Network Diagram Example

PDM Network Diagram Example

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).

3. Estimating Activity Resources

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.

3. Estimating Activity Resources (cont.)

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

3. Estimating Activity Resources (cont.)

4. EstimatingActivity Durations

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.

4. EstimatingActivity Durations

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.

Three-Point Estimates

5. Developing The Schedule

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.

5. Developing The Schedule (cont.)

Tools used for schedule development:

◦Gantt chart.

◦Critical path method.

◦PERT.

◦Critical Chain scheduling.

5. Developing The Schedule (cont.)

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.

5. Developing The Schedule (cont.)

Sample of Gantt chart

5. Developing The Schedule (cont.)Gantt chart for software lanuch project

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.

5. Developing The Schedule

5. Developing The Schedule (cont.)

Critical Path Method CPM

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.

5. Developing The Schedule (cont.)

Critical Path Method CPM

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.

5. Developing The Schedule (cont.) Critical Path Method CPM

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.

5 .Developing The Schedule (cont.)

Example on CPM

Begin

1 3 6

2

4

5

7

A

D

E

G

K

F

I

JC

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)

5. Developing The Schedule (cont.)

Example on CPM

Find the Longest Path:Path 1 = A, D, G, K, L = 22 daysPath 2 = A, E, H, K, L = 19Path 3 = A, E, I, L = 15Path 4 = B, H, K, L = 20Path 5 = B, I, L = 16Path 6 = C, F, J, L = 19

Path 1 [ A,D,G,K,L ] is the critical path duration, because it is the longest path.

5. Developing The Schedule (cont.)

Critical Path Method CPM

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.

5. Developing The Schedule

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).

5. Developing The Schedule (cont.)

Critical Chain Scheduling

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.

5. Developing The Schedule (cont.)

Critical Chain Scheduling

5. Developing The Schedule (cont.)

Example on Critical Chain SchedulingThree tasks without multitasking:

Three tasks with multitasking:

5. Developing The Schedule (cont.)

Critical Chain Scheduling

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.

5. Developing The Schedule (cont.)

Critical Chain Schedule Example

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.

5. Developing The Schedule (cont.)

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

6Therefore, you’d use 12 days on the network diagram instead of10 when using PERT for the above example.

5. Developing The Schedule (cont.)

PERT Formula and Example

5. Developing The Schedule (cont.)

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.

6. Controlling The Schedual

Word-processing software. Spreadsheets help to perform financial calculations. Communication software. Project management software. Decision support models.

Using Software to Assist in Project Time Management

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.

Chapter Summary