Mod3 Funda Proj Network PERT

8/18/2019 Mod3 Funda Proj Network PERT

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Program Evaluation Review

Technique (PERT)Prof.G.Purandaran

M.Tech (I.I.T-Madras)

PGDM (I.I.M-Bangalore)


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Objective of theresentation

• To understand the formula , the useand the benets of Program ,Evaluation ,and Review Technic(PERT) analysis .


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Program (Proect) Evaluation and Review Technique (PERT)! is a "roect management toolused to schedule, organi#e, and coordinate tas$swithin a "roect. %t is basically a method to analysethe tas$s involved in com"leting a given "roect,es"ecially the time needed to com"lete each tas$,and to identify the minimum time needed tocom"lete the total "roect.

!hat is the P"#T $


4/23

!hen %e use P"#T $

•

P"#T is used when activit& ti'es are uncertain. – &etermine the duration of the "roect .

– &ecision ma$ing under ris$ ('P for "robabilistic)


5/23

Deter'ine the duration ofthe roject

• OPTIMITI TIM"! Best time if everything goes

"erfectly• RE*%+T% T%-E! Most li$ely time

• PE++%-%+T% T%-E! worstcase situation

B / 0M / P

E1"ected Time 2 3


6/23


• "*a'le+,or e*cavation activit& let +

B / da&s

M 0 da&s

P 12

!hat is the e*ected ti'e for this activit&$

ol +

/ / 0(0) / 12

E1"ected Time 2 3

2 40 days


7/23



8/23


+tart

5

6E

&

7

5inish


9/23


+tartE+!8E5!8

5&!0.9

E+!:8.;;E5!:0..:=

6&!9.:=

E+!:0.;0E5!:>.9:

E&!9.:=E+!>.:=E5!:0.;0

&&!3.;;

E+!0E5!:8.;;

7&!9.;;E+!8

E5!9.;;

&!0E+!8E5!0

5inish&!8

E+!:>.9:

E5!:>.9:


10/23


tartD+2"+2",+23+2

3,+2

,D+4.5

"+2.66

",+4.063+5.23,+7.5

D+5.8"+4

",+7.83+4

3,+7.8

GD+5.8

"+4.64",+7.53+4.64

3,+7.5

"D+5.8"+7.8",+4.643+7.8

3,+4.64

DD+1.66"+4

",+2.663+0.103,+5.2

BD+5.66"+2

",+5.663+6.04

3,+7.8

9D+4"+2",+43+2

3,+4

,inishD+2

"+7.5",+7.5

3+7.53,+7.5


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ritical Path

ritical Path! E6

• Path &5 2 :0.


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ritical Path


13/23

9ssessing #is:s

• #is: is a measure of the "robability(and consequences) of not com"letinga "roect on time.

•

maor res"onsibility of the "roectmanager at the start of a "roect is todevelo" a ris$management "lan.

• #is:-Manage'ent Plan identies

the $ey ris$s to a "roect?s success and"rescribes ways to circumvent them.


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• @ith PERT?s three timeestimates, we get amean (average) time and a variance for

each activity and each path.

–

@e also get a project mean timeand variance.

• %n order to com"ute "robabilities (assuming a

normal distribution) we need the activity

means and variances.

– -ost com"uter "ac$ages calculate this for you.

9ssessing #is:s


15/23

A

3

:8

6

;9

B

0

C

08

7

>

&

:8

E

40

%

:9

5inish+tart

:4

5

:8

8 >

> ;;

> :> :> 9>

44 9=:4 44

9> 3;

:4 4=

:4 44 3; 3>8 :4

0< 3;

9; 3;

9> 3;

40 9>

:> 9>

;9 9>

:0 40

> :>

4 :0

8 >

*atestnishtime

3; 3>

*ateststarttime

Path Time

(w$s)

%A ;;;;

5A 4<4<

6BA 3=7&CBA 3>7EBA 0;

9ssessing #is:s


16/23

•@hat is the "robability that our sam"le"roect will nish in 3> wee$s as scheduledD

:88 (@hyD)

–7ecause we used P-F• (This means we were certain of all of our activity

times.)

– %f we weren?t certain, we should have used PERT

• Gou can?t do ris$ analysis if you use P-

9ssessing #is:s


17/23

• alculate standard deviation – +tandard deviation average deviation from the

estimated time• +&2(TPT8)H3

– higher the +& is the greater amount of uncertainty

e1ists

• alculate variance – reIects the s"read of a value over a normal

distribution• J2+&4

– a large variance indicates great uncertainty, asmall variance indicates a more accurate estimate

9ssessing #is:s


18/23

(variances of activities along critical ath); T <

σ

/

.80 = .80 = /.80 = 5.44 = 2. .07

; 8/ < 17

.07

!hat is the Probabilit& of it ta:ing 8/%ee:s$ritical Path B - D - > - ? < @ 17 %ee:s

T 8/ %ee:s 17 %ee:s

*oo$ u" K value in normal distribution tableP# 2 .


19/23

*oo$ u" the K value (8.


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Proect duration (wee$s)

3> =4

Probability ofta$ing =4 wee$sis 8.


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• ssume a PERT "roect critical "ath ta$es 42 da&s, and that

the variance of this "ath is 4.:0= – Gou wish to $now the "robability of the "roect going over 04 days.

• om"ute the standard deviation of the critical "ath. (Ta$e the

square root of the variance of 4.:0=) +td. &ev. 2 :.039

– POM/QM software gives you the variance of the critical path.

• om"ute the A value! K 2 (absolute time diOerence) H +td.&ev.

%n this e1am"le, K 2 (04 days 08 days) H :.039 2 .615

• *oo$ u" the K value of .615 in a Mormal &istribution table to

get the "robability of the "roect ta$ing 04 days.

• +ubtract it from :88 to get the "robability of going over 04.

9ssessing #is:s


22/23

*oo$ u" the K value (:.;39) in the table of normal

distribution.

(%n this case you need to inter"olate between the K values of .>;:; and .

>:0=)

.>:;> or >:.;> is the "robability of the "roect ta$ing u" to

04 days.

9ssessing #is:s


23/23

Than: &ou for attention

9n& Cuestions $$$$

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