Software Project Management Task Sequencing

Activity Sequencing Concepts

PERT charts

Critical Path Analysis

Project Time Management Processes

Project time management involves the processes required to ensure timely completion of a project. Processes include:

Activity definition (your WBS) Activity sequencing (this topic) Activity duration estimating (next week)

Activity Definition•This comes from your WBS

Recall it encompasses the total scope of the project It is organized by a perspective, or organizing principle

•What it doesn’t do: Help you plan temporally You need to know X needs to be done before Y because X may

produce a deliverable (or knowledge) required for Y You may need to ensure you can provide all of the resources

(people, technology, etc.) at a given time to ensure success

Time

Quality

Scope

CostExpectations

Activity SequencingInvolves developing a more detailed WBS and supporting

explanations to understand all the work to be done An outgrowth of your WBS’ work packages Initial dependencies should arise

• What needs to be done before to make data available (flow)• What tasks are a “part of” other tasks (decomposition)• This is the resulting sequencing of activities to achieve goals

Review activities and determine dependencies Mandatory: inherent in the nature of the work; hard logic

• Example: Coding must happen before testing

Discretionary: defined by the team; soft logic applied within a process• Example: Order in which components are implemented

External: involve relationships between project & non-project activities• Example: 3rd party / open source software release

Resource: Multiple projects depend on same resource• Example: You have only 1 Oracle-certified DBA but 2 projects

Activity Sequencing

Tools for Activity Sequencing Task networks, PERT charts, Critical Path Analysis

Task networks A graphical representation of tasks Visualizes tasks, flows, and relationships Two formats:

• Activity-on-Arrow (AOA)– Nodes represent Events, Lines represent Tasks

• Activity-on-Node (AON)– Nodes represent Tasks, Lines dependencies between Tasks

AON:

STARTCode

Module

WriteUnit Test

PerformCode Review

FixDefects

Check-inCode

AOA Example

*Taken from Scach 4th ed. P. 289

Activity Sequencing

Temporal Dependencies between Tasks• Finish-to-Start (FS)

B cannot start till A finishes A: Construct fence; B: Paint Fence

• Start-to-Start (SS) B cannot start till A starts A: Pour foundation; B: Level concrete

• Finish-to-Finish (FF) B cannot finish till A finishes A: Add wiring; B: Inspect electrical

• Start-to-Finish (SF) B cannot finish till A starts (rare)

Critical Path Method (CPM)

CPM is a project network analysis technique used to predict total project duration A critical path 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 Typically used in conjunction with PERT charts (or also with Activity-

Task Analysis, Task Networks, etc.)

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

Course Technology, 1999

Determining the Critical Path

Consider the following project network (AOA) diagram. Assume all times are in days.

2 3

4

5

A=2 B=5C=2

D=7

1 6

F=2

E=1

start finish

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?

Course Technology, 1999

Determining the Critical Path

Course Technology, 1999

Example (AOA):

More on the Critical PathMisconceptions:

The critical path is not the one with all the critical activities; it only accounts for time

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

If one of more activities on the critical path takes longer than planned, the whole project schedule will slip unless corrective action is taken We will discuss what “corrective actions” are possible

with scheduling next week.

Course Technology, 1999

PERT ChartsProgram Evaluation and Review Technique

Network analysis technique used to estimate project duration if there is a high degree of uncertainty about individual activity duration estimates

PERT uses probabilistic time estimates based on using optimistic, most likely, and pessimistic estimates of activity durations

Course Technology, 1999

Prepare Material forBusiness Management

98/29/95 9/4/95

Conduct the BusinessManagement Review

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RD Approved by IS Dir,DMA Dir, Cust Sponsor

119/11/95 9/11/95

Approval to Proceed toNext Stage

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RequirementsDefinition (Analysis)

18/1/95 9/11/95

Prepare for Analysis

28/1/95 8/7/95

Analyze the CurrentSystem

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Develop and EvaluateAlternative Solutions

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Plan the Next Stage

88/22/95 8/28/95

Reaccess ApplicationArchitecture

58/8/95 8/14/95

Outline Transaction,Security and Training

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Define SystemRequirements (Business)

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ITDE(0.3),ITI

ITDBA(0.3) ITDBA(0.3)

EXAMPLE: