Slide 7.1

4E1 Project Management

Planning 2 Estimating and Scheduling

Slide 7.2

Key Concepts

Estimating

Scheduling

Gantt charts

Network notations

Slide 7.3

Exercise

Take a blank sheet of paper• Divide it into five columns as follows:

# Best guess Upper estimate Lower estimate

1 2 3 .. 10

There should be ten rows to write on.

Slide 7.4

Test Your General KnowledgeFor each item, write (a) best guess and (b) upper and lower estimates that you are 90% confident of.

1. Distance in miles from Moscow to Santiago (in Chile)

2. Gold medals won by Finland in summer Olympics 1896-1992

3. Area of Greenland in square miles

4. Year the ballpoint pen was invented

5. Year the HJ Heinz company was founded

6. Population of Belize in 1990

7. Denmark’s GNP in $US in 1989

8. Year that Louis Braille was born

9. Average depth of Pacific ocean to nearest 1,000 feet

10. Length in miles of the river Danube

Slide 7.5

Answers

1. Distance from Moscow to Santiago is 10,118 miles2. Finland won 97 gold medals in summer Olympics 1896-

19923. The area of Greenland is 839,781 square miles4. The ballpoint pen was invented in 19385. The HJ Heinz company was founded in 18766. The population of Belize in 1990 was 187,0007. Denmark’s GNP in $US in 1989 was $105,238 million8. Louis Braille was born in 18099. The Pacific ocean is 14,000 feet deep on average10. The river Danube is 1,770 miles long

Slide 7.6

Why are Estimates So Often Wrong?

Internal causes• Psychology: over-confidence, optimism, ego

• Misjudgement: inexperience, uniqueness of project

• Failure to learn from previous projects

External pressures• Management pressure, sales imperative

Other causes• Games, inadequate specifications, unclear objectives

• Rarely, bad luck

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Example: Software Estimating How many steps in this C program to convert Fahrenheit to Celsius?

#define LOWER 0#define UPPER 300#define STEP 20main()

{int fahr for (fahr=LOWER

fahr<=UPPER fahr=fahr+STEP)

print(“%4d %6.1f\n”,fahr,(5.0/9.0*(fahr-32))}

Slide 7.8

Experts’ Estimates

0

2

4

6

8

10

12

One Two Three Four Five Six Seven Eight Nine

No. of Experts

Slide 7.9

Estimating – Broad StrategiesBases

• Experience, similar work in previous projects• Detailed breakdown/WBS• Heuristics e.g. function points

Types• Ballpark, comparative, feasibility, detailed• Top-down vs bottom-up

Risks• Theoretical versus actual resource costs• Cumulative effect of small errors

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Scheduling: Context

StatutoryRegulations

Acts of God

Market Conditions

CorporateStrategy

FiscalPolicy

Organisationstructure

Proceduresand systems

Communications

Resourcesand capacity

Attitudes and culture

Technicalcapability

SupportingServices

Managementskills

ProfitTimeQuality

External Factors

Working factors

Contribution to results

Planningand

Scheduling

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The Bar (Gantt) Chart

Design

Set up

Manufacture

Test

Task

Time

Purchasematerials

Implicit dependency

Overlap

Henry Gantt

Lag

Explicit dependency

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Gantt Charts in Practice

Slide 7.13

ExerciseDraw a Gantt chart for your “Gulliver Experience” project, showing only the top-level tasks (i.e. about 7 phases)

• Planning Project plan, agree requirements

• Outsource project Issue request for tenders, review proposals, award contract

• Design Architectural design, detailed design and blueprints, order materials

• Move TCD administration Prepare new location, move

• Construction Site preparation, building, fit-out

• Set up business Establish company, hire staff, implement systems, marketing

• Commence business operations

Add estimated durations, start and end dates, dependencies and resources

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Network Diagrams

1

84

36

9

7

52

1 432Get up Eat breakfast Go to college

10 20 30

Activity on arrow

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Activity Properties

Description

Resources: human, other

Work/non-work

Duration

Dates: earliest start, latest finish

Dependencies: predecessors, successors

Other constraints

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Precedence

1

84

36

9

7

521

3 5

24

4

3

4

55

18

6

Dummy task (dashed line) indicates order• Node 4 precedes node 5

• Therefore tasks 5 and 8 cannot start until task 3 is complete

Slide 7.17

Types of Network Diagram

Two basic types:

Activity on arrow (most intuitive)• Arrow diagrams (ADM)

• Critical Path Method (CPM)

• Critical Path Analysis (CPA)

• Project Evaluation and Review Technique (PERT)

Activity on node (suits computers)• Precedence diagrams (PDM)

• Rare but still used Method of potentials (MPM)

Activities on circular nodes

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Precedence Diagrams

Get up10

Eat breakfast20

Go to college30

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Precedence Diagrams - Dummy Tasks

Not customary but can be useful

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Exercise

A

B

D

C

F

W

G

E

V

X

Y

Z

Activity AF

Activity BE

Activity CE

Activity DE

Activity FV

Activity FW

Activity FX

Activity GY

Activity GZ

Redraw this arrow diagram as a PDM (a) with dummy tasks and (b) without dummy tasks

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Solution (without dummy tasks)

CE

AF

DE GY

FX

FV

BE FW

GZ

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Solution (with dummy tasks)

CE

AF

DE GY

FX

FV

BE FW

GZ

Dummy 2

Dummy 1

Slide 7.23

Network Notations - Example 1

Screed Floor

D =26 Bus = 35ES = 2/10 LS = 15/10 EC = 6/11 LC = 23/11Res = FEB, JH

Duration

ActivityDescription

Earliest Start Date

Earliest CompletionDate

ResourcesAssigned

LatestCompletionDate

LatestStart Date

Elapsed time

B1.3

Activity Code

Networks use standard notation as follows:

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Activity identifier

Earliest event time

Latestevent time

1025

17

5 10 15

8 3 18

Earliest start time

DurationEarliest finish

time

Latest start time

Total float Latest finishtime

Activity identifier and descriptionResources required.

Network Notations - Example 2

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14/11/06 5 15/12/06 4.2.3 Specify Hardware3/12/06 17 18/1/05JO’D €2,500 0%

Earliest Start Time Duration

Earliest Finish Time

Latest Start Time

Latest Finish Time

Total Float

Resources/Responsibility

Budget% Complete

Task ID

Task Description

Network Notations - Example 3

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Gantt vs Network

Both used widely

Gantt• Simpler, easier to grasp

• Limited in ability to show dependencies

• Easily cluttered

Networks• More meaningful, more information

• Harder to read

• Often large and complex

Slide 7.27

Summary: Key Points

Estimating• Part science, part art

• Tools help but judgment is required

Gantt charts• Most basic tool; intuitive but limited

Network (arrow/precedence) diagrams• More powerful, less intuitive