2 Project Scheduling

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Project Scheduling and HR Planning

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Network Diagram

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A network diagram is a sequence of steps (activities) thatare linked together in the logical sequence they need to

be carried out.

Provides the project team a consensus of understanding

of how the project should be implemented Planning should not be done alone, it's a group activity,

Boosts efficiency of understanding and communication

Facilitates important buy-in from the whole Project Team.


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Example: Network Diagram

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No looping back is alloweddeal with iterations

by hiding them within single activities


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Types of activity dependency

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Finish to start (FS) The following activity starts when the previous one has been

finished

Default type of dependency (e.g. in MS Project)

Software

development Acceptance testing


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Start to start (SS) When one activity starts another has to start as well

Finish to finish (FF)

when one activity finishes the other must finish too

Test prototype

Document

Amendments

1 day 2 days

SS FF

You could use these with lags.

E.g. documentation of the changes to the

prototype starts 1 day after the testing and

finishes 2 days after testing has been completed


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Start to finish (SF) An activity will end when another activity starts

Operate temporarysystem

Acceptance testof new system

Cutover to newsystem


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Nature of dependency

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Mandatory dependency Inherent in the nature of work to be performed on a project

Relationship is unavoidable

E.g. You cannot hold a training class until the training materials

are ready Discretionary dependency

Defined by the project team

E.g. The project team follow good practice and does not start

detailed design work until stakeholders sign off on all theanalysis work


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External dependency Relationship between project and non-project activities

E.g. Installation of new software might depend on delivery of

new hardware from external supplier


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Critical path method (CPM)

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The critical path method (CPM), is a mathematically basedalgorithm for scheduling a set of project activities.

A critical path for a project is the series of activitiesthat determines the earliest time by which the project canbe completed

Forward pass

How early can we complete this project?

Backward pass

How late can we start any activity without delaying theproject?


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Start and finish times

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Earliest start (ES)

Latest start

= LF - duration

Latest Finish (LF)

= latest task can be completed

without affecting project end time

Earliest finish (EF)

= ES +duration

activity

Earliest start = day 5

Latest finish = day 30

Duration = 10 days

Earliest finish = ?

Latest start = ?


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Activities

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Activity label, activity description

DurationEarlieststart

Earliestfinish

Latest

startLatest

finishTotal Float


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Forward pass

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Start at beginning (Day 0) and work forward Earliest start date for the current activity = earliest finish

date for the previous

When there is more than one previous activity, take the latest

earliest finish

EF = day 7

ES = day 7

EF = day10

ES = day10


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0 6 6 9

0 4 4 8

0 10 4 7

9 11

10 13

How early can the project be completed?


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Backward pass

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Start from the last activity and work backwards

Latest finish for current activity = Latest start for the

following activity

More than one following activity - take the earliest LS Latest start (LS) = LF for activity - duration

LS = day 7LF = day 7

LS = day 6

LF = day 6


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0 6 6 9

0 4 4 8

0 10 4 7

9 11

10 13

2 8 8 11

3 7 7 11

0 10 7 10

11 13

10 13

How late can we start any activity without

delaying the project?


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Total float (Total Slack)

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Represents the amount of time an activity can be delayed

without delaying the project.

Total float = LF - ES - duration or LS- ES or LF-EF


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Example: Total float

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0 6 6 9

0 4 4 8

0 10 4 7

9 11

10 13

2 8 8 11

3 7 7 11

0 10 7 10

11 13

10 13

2

3

0

2

3

3

2

0


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Critical path

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Any delay in an activity on the critical path will delaywhole project

Methods to find the critical path

Find the longest path through the network diagram

Calculate total float for each activity on the WBS using anetwork diagram. Critical path is the one with all activities

with 0 floats


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Example: critical path

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0 6 6 9

0 4 4 8

0 10 4 7

9 11

10 13

2 8 8 11

3 7 7 11

0 10 7 10

11 13

10 13

2

3

0

2

3

3

2

0


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More about critical paths

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If one of more activities on the critical path takes longerthan planned, the whole project schedule will slip unlesscorrective action is taken

The critical path may change as you enter actual start andfinish dates during project execution


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Free float (Free Slack)

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The time an activity can be delayed without affectingany other activity.

Free Float = ES for following activity - EF for the

current activity


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Free float: example

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Consider activity D. The starting date can be delayed 3 weeks without

affecting the project end day.

However, the start date of H will be affected

(4+3+4=11).

6 9

4 8 9 11

8 11

7 11 11 13

2

3 2

The free float for activity D

= 9 - 8 = 1.

D can only be delayed for up to 1 day without

affecting H.


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CPM vs PERT

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CPM is for repeated projects Assume an accurate estimate of duration activity

PERT - "Project Evaluation and Review Technique"

Risk-based approach for duration estimation


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Estimation in activity duration

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Pessimistic time = 10 daysOptimistic time = 4 days


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Three-point estimating in PERT

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Most likely time (m), Optimistic time (a),Pessimistic (b)

Expected activity duration

te = (a + 4m +b) / 6

Standard deviation of activity duration s = (b-a)/6


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Example

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Joe, a network engineer, has been asked to give a timeestimate for setup of a new Cisco switch that he has

never worked with before.

How long will it take for Joe to configure, test, and

deploy the switch?


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The last time he did something similar with an earlier model of

Cisco switch, it took him a total of 40 hours, so Joe assigned a

most likely estimate of 40 hours.

But now that Joe has done it once and he expects this process

to be similar, he might be able to get it done faster, so Joe's

optimistic estimate is 20 hours.

But recently Joe read an article stating that Cisco had

completely changed the configuration module for this upgrade,

so it may take longer than it did last time; Joe therefore assigns

a pessimistic estimate of 56 hours.


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Example

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What is the expected project duration?

What is the standard deviation for expected project duration?

Task a m b te s

A 10 12 16

B 8 10 14

C 20 24 38

Task A

Task B

Task C


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Task A

Task B

Task a m b te s

A 10 12 16 12.66 1

B 8 10 14 10.33 1

C 20 24 38 25.66 3

Task C

Critical path = (A, C)

Expected end time = 12.66+25.66 = 38.32

Std dev (Expected end time) = sqrt (12+32) = 3.16

E(A+B) = E(A) + E(B)

V(A+B) = V(A) + V(B) + COV(A,B)


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Likelihood of meeting a target

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Expected end time = 38.32 Assume the day-of completion follows the normal

distribution (Why?)

The chance of project completion by this time is 50%

38.32


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Table of Normal Distribution

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Assessing the likelihood

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Say the project deadline is 42 days

What is the probability that of completing the project by

the deadline?

z = (T te)/s

= (42-38.32)/3.16

= 1.164

The deadline is 1 standard

deviation above the expected

duration 38.82 42


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Graph of z values

Note: The STANDARDIZE calculation in Excel can be used to calculate the Z value.

Probability of meeting the deadline is 100-15% = 85%

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Schedule development

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Uses the results of the other time management processes

(activity definition, sequencing, estimating) to determine the

start and end date of the project

Determines the planned start and completion dates for each

activity listed on the WBS.


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Gantt chart

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A type of bar chart that illustrates a project schedule

Activity network with start and end days


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Project milestones

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Significant important events on a project

E.g. Sign-off of key documents, completion of specific products,

completion of important process-related work (e.g. awarding a

contract to supplier)

Often used by project sponsors or senior managers to

assess and monitor the project progress

No cost or duration is associated with a milestone


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Major milestones

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The major milestones give

visibly or progress to

people external to the

project.

E.g. project sponsors and

customers.

Milestone Milestone Goal

Concept approval

Feasibility studies and basic system concepts

have been approved by management and the

project is authorized to proceed to detailedrequirements definition.

Requirements review

Requirements specifications are complete,

correct, approved and suitable for input to

design.

Preliminary design review

The architectural design satisfies all product

requirements, is approved and is suitable for

input into the detailed design process.

Critical design review

Detailed designs fully implement the system

architecture, are approved and are suitable for

input into the development of code.

Test plan review

Test plans are adequate for the testing of all

product features, are approved and are suitable

for input to the development of test cases and

test procedures.

Test readiness review

Developed and unit tested software has been

passed by the test team and is suitable for input

into integration testing.

System test reviewThe software product has passed systemtesting and is suitable for input into acceptance

testing.

Operational readiness review

The software product has passed acceptance

testing and is suitable for deployment in its

target production environment.

Product operationalThe software is in use in its target operational

environment.

http://www.chambers.com.au/glossary/milestone.php
http://www.chambers.com.au/glossary/milestone.phphttp://www.chambers.com.au/glossary/milestone.php


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Minor milestones

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Minor milestones are the

monitoring points you as

project manager use to

maintain control of day to

day activities.

Give the team a sense of

achievement by

demonstrating progress on

a daily or weekly basis

Milestone Milestone Goal

Document outline complete

A document outline has been

produced describing the format,

content and objectives of each

major section of a largedocument.

Document complete

A document such as an Software

Requirements Specification has

passed peer review.

Technical investigation complete

The investigation of a technical

issue is complete and a summary

of the main issues and conclusions

has been presented and approved.

Compile completeA program compiles without

errors.

Software module completeA small program or function has

been completed and unit tested.

Software product build complete

The software product (or one of

its components) has been built an

it runs (not necessarily without

errors).

Test case complete

A small unit of testing has been

completed and test results

recorded.

Bug fix complete

A bug identified in a Software

Anomaly Report (SAR) has been

fixed and the SAR closed out.

T h i f h i j


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Techniques for shortening a project

schedule (schedule analysis)

Knowing the critical path helps you make schedule trade-offs

Techniques

Replace a team member with a more skilled person

Shortening durations of critical tasks by changing their scope Delay tasks with positive float and move resource to work

with tasks on critical path.

Crashing

Fast tracking

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Crashing

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For each task in the critical path, look for the task that

could be done faster if more resources were added.

Goal:

Look for the task that would deliver the most compression for

the least incremental cost

C hi th h d l S ft


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Crashing the schedule: Software

development example

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Duration =Work

Resource unit

Duration is

shortened by 1

day

Add 1 more programmer

to task 11

Effort driven:

As resources are added to or removed froma task, the task duration is adjusted but the

total work on the task stays the same.


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Fast tracking

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Look for activities in the critical path that can be done in

parallel

May involve the need to add more resources

To perform two tasks in parallel, the input of one task

should not depend on the output of another task

F t t ki S ft d l t


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Fast tracking: Software development

example

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Design and code can be performed in parallel

Wh t if f d i d di i


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What if we perform design and coding in

parallel?

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Human Resource Management Planning

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Team building activities

Keeping team members motivated

Reward/Recognition

Tangible (e.g. cash, gifts)

Intangible (e.g. praise, favorably mention in monthly report or meetings, training)

Training Acquire the skills required for the project

When people feel that theyre growing professionally, they stay more involved

and get more excited by their work.


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Staffing Management Plan

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Allocating individuals to activities

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Factors Availability - who is free?

Criticality - put more experienced, safer, staff on the criticalactivities

Risk

Training - by allocating challenging tasks to relativelyinexperienced staff

Based on the capability of the resource and the effort, wecan create duration/time estimates for each activity


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References

Information Technology Project Management, 7th Edition

Chapter 6

Documents

2 Project Scheduling