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Copyright 2012 John Wiley & Sons, Inc.

Chapter 8

Scheduling

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8-3

Background

Sched"le is the con!ersion o' a pro(ect action

plan into an operating timeta)le

*asis 'or monitoring a pro(ect+ne o' the ma(or pro(ect management tools

Wor changes daily, so a detailed plan is

essential

ot all pro(ect acti!ities need to )e sched"led at

the same le!el o' detail

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8-4

Background Continued

Most o' the sched"ling is at the W*S

le!el, not the $or pacage le!el

+nly the most critical $or pacages may)e sho$n on the sched"le

Most o' the sched"ling is )ased on

net$or dra$ings

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8-5

et!ork Scheduling Advantage

Consistent 'rame$or

Sho$s interdependences

Sho$s $hen reso"rces are neededns"res proper comm"nication

etermines e/pected completion date

Identi'ies critical acti!ities

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8-6

et!ork Scheduling AdvantageContinued

Sho$s $hich o' the acti!ities can )e

delayed

etermines start datesSho$s $hich tas m"st )e coordinated

Sho$s $hich tas can )e r"n parallel

#elie!es some con'lict

llo$s pro)a)ilistic estimates

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et!ork Scheduling Techni"ues# PERT$A%M& and CPM $P%M&

P#% $as de!eloped 'or the Polarismissiles")marine pro(ect in 134

CPM de!eloped )y "Pont d"ring the same

time Initially, CPM and P#% $ere t$o di''erent

approaches5 CPM "sed deterministic time estimates and allo$ed

pro(ect cr"nching5 P#% "sed pro)a)ilistic time estimates

Microso't Pro(ect 6and others7 ha!e )lendedCPM and P#% into one approach

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Ter'inolog( Continued

Path- series o' connected acti!itiesCritical- n acti!ity, e!ent, or path $hich,

i' delayed, $ill delay the completion o' thepro(ectCritical Path- %he path thro"gh the

pro(ect $here, i' any acti!ity is delayed,the pro(ect is delayed5 %here is al$ays a critical path

5 %here can )e more than one critical path

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Ter'inolog( Continued

Se"uential Activities- +ne acti!ity m"st

)e completed )e'ore the ne/t one can

)eginParallel Activities- %he acti!ities can

tae place at the same time

)''ediate Predecessor- %hat acti!itythat m"st )e completed ("st )e'ore a

partic"lar acti!ity can )egin

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Ter'inolog( Continued

Activit( on Arro!- rro$s represent

acti!ities $hile nodes stand 'or e!ents

Activit( on ode- odes stand 'ore!ents and arro$s sho$ precedence

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A* and A*A +or'at

8ig"re 4-9

8ig"re 4-2

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Constructing the et!ork

*egin $ith S%#% acti!ity

dd acti!ities $itho"t precedences as

nodes5 %here $ill al$ays )e one

5 May )e more

dd acti!ities that ha!e those acti!ities asprecedences

Contin"e

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,antt $Bar& Charts

e!eloped )y :enry ;.

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Advantages and %isadvantage

d!antages5 asily "nderstood

5 Pro!ide a pict"re o' the c"rrent state o' apro(ect

isad!antage

5 i''ic"lt to 'ollo$ comple/ pro(ects

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Microsoft Pro-ect ,antt Chart

8ig"re 4-11

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Microsoft Pro-ect A* et!ork

8ig"re 4-12

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8-18

Solving the et!ork

%a)le 4-1

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8-19

The A* et!ork fro' the previoustable

8ig"re 4-19

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8-20

Calculating Activit( Ti'es

( )

( )

2

2

2

6

6

4

=

=

++=

ab

bmaTE

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8-21

The Results

%a)le 4-2

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8-22

Critical Path and Ti'e

8ig"re 4-13

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8-23

Critical Path and Ti'e Continued

8ig"re 4-1=

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8-24

Slack

8ig"re 4-1=

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8-25

Slack .alues

%a)le 4-9

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8-26

Precedence %iagra''ing

8inish to start

Start to start

8inish to 'inishStart to 'inish

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8-27

Precedence %iagra''ing Conventions

8ig"re 4-1>

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8-28

Microsoft Pro-ects

%a)le 4-?

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8-29

,antt Chart

8ig"re 4-14

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8-30

A* et!ork

8ig"re 4-1

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8-31

Microsoft Pro-ect Calendar

8ig"re 4-29

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8-32

Uncertaint( of Pro-ect Co'pletion Ti'e

ss"me acti!ities are statistically

independent

@ariance o' a set o' acti!ities is the s"mo' the indi!id"al !ariances

Interested in !ariances along the critical

path

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8-33

E/a'ple

( )

( ) 45.52645.1745.543

22.1745.5

7

33

4350)(

2

=+=+=

==

=

=

ZD

DZ

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8 3

To!ard Realistic Ti'e Esti'ates

Calc"lations are )ased on 1A chance o'

)eating estimates

Calc"lations can also )e )ased on 3A or 10A

Changing the percentage re"ires changing the

'orm"lae 'or !ariance

When "sing 3A, the di!isor changes to 9.2

When "sing 10A, the di!isor changes to 2.3=