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Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
1
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MODULE - 9 LECTURE NOTES – 3
MULTI-CRITERIA DECISION MAKING
INTRODUCTION
Multicriterion decision making (MCDM) is a process of evaluating real world situations,
based on various qualitative / quantitative criteria in certain / uncertain / risky environments
to suggest a course of action / choice/ strategy / policy among the available options. In this
lecture we will discuss about the structured decision making and various MCDM methods.
STRUCTURED DECISION MAKING
The evaluation of multicriterion situations using conventional approaches may be difficult. A
structured decision making (SDM) is necessary to visualize the decision making. It also helps
in replicating the same steps if the given decision is proved to be right. The steps in SDM are
shown in figure 1. These steps are to be followed to arrive at an effective decision.
Fig. 1 Steps in SDM
Purpose and necessity of decision making
Identification of decision makers
Identification of criteria that will influence decision making
Assume suitable priority to each criterion
Formulate various strategies on which criteria can be evaluated
Estimate each strategy using SDM
Determine the suitable strategy
Implement the strategy
Evaluate the outcome of the decision
Document the lessons that have been learnt in this process for
further improvement of decision making skills
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
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STEPS IN MCDM METHODOLOGY
The steps for the selection of best alternative from a set of available alternatives are
(Duckstein et al., 1989):
Defining the problem and fixing the criteria
Data collection
Establishment of feasible alternatives
Formulation of payoff matrix i.e., matrix comprising evaluation of alternatives with
reference to criteria
Selection of appropriate method
Incorporation of decision maker’s preferences
Choosing one or more best alternatives for further analysis
MCDM METHODS
MCDM methods can be classified into four groups:
1. Distance
(a) Compromise Programming (CP)
(b) Cooperative Game Theory (CGT)
(c) Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS)
(d) Composite Programming (COP)
2. Outranking
(a) Preference Ranking Organisation METHod of Enrichment Evaluation
(PROMETHEE)
(b) ELimination Et Choix Traduisant la REalite (ELECTRE)
3. Priority / Utility and
(a) Weighted Average Method
(b) Multi Attribute Utility Theory
(c) Analytic Hierarchy Process
4. Mixed category
(a) Multicriterion Q- Analysis -2
(b) EXPROM-2
(c) STOPROM-2
In this lecture we will discuss about compromise programming, PROMETHEE and weighted
average method.
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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COMPROMISE PROGRAMMING (CP)
The objective in CP is to obtain a solution that is as ‘close’ as possible to some ‘ideal’
solution in terms of distance. The distance measure used in Compromise Programming is the
family of Lp - metrics and expressed as
pJ
j
p
jj
p
jp affwaL
1
1
)()( * (1)
Normalizing between the range [0, 1], eqn. (1) becomes,
pJ
j
p
jj
jjp
jpmM
affwaL
1
1
)()(
*
(2)
where )(aLp = pL - metric for alternative a, )(af j = Value of criterion j for alternative a,
jM = Maximum value of criterion j in set N , jm = Minimum value of criterion j in set N ,
*
jf = Ideal value of criterion j, jw = Weight assigned to the criterion j, p =
Parameter/balancing factor reflecting the attitude of the decision maker with respect to
compensation between deviations. For p = 1, all deviations from *
jf are taken into account in
direct proportion to their magnitudes. For p , the largest deviation is the only one taken
into account corresponding to zero compensation between deviations. The flow chart of CP
methodology is given in figure 2.
Fig. 2 Flow chart of Compromise Programming methodology
Enter the number of alternatives, criteria, payoff matrix, and weight
of each criterion
Specify the parameter p ; Compute pL - metric value
Print results
Start
Stop
Rank alternatives based on minimum pL - metric value
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Example
Compute pL - metric values of alternatives and corresponding ranking pattern for the payoff
matrix presented in Table 1 [Brans et al. (1986)] using Compromise Programming method
for p = 1, 2, . Assume equal weights for each criterion. Alternatives A1 to A6 in payoff
matrix represent hydropower projects and criteria C1 to C6 correspond to man power,
Hydropower (MW), construction cost (109 $), maintenance cost (10
6 $), number of villages
to be evacuated and security level respectively.
Table 1. Payoff Matrix
Crit.
Alt.
C1 C2 C3 C4 C5 C6
A1 80 90 6 5.4 8.0 5
A2 65 58 2 9.7 1.0 1
A3 83 60 4 7.2 4.0 7
A4 40 80 10 7.5 7.0 10
A5 52 72 6 2.0 3.0 8
A6 94 96 7 3.6 5.0 6
Max/Min Min Max Min Min Min Max
Solution:
Negative sign is assigned to the criterion of minimization in nature to enable to analyze the
problem uniformly in maximization perspective i.e., (-min) = max. Table 2 presents payoff
matrix after this transformation, where all criteria are made to be of maximization in nature.
Table 2. Transformed payoff matrix
Crit.
Alt.
C1 C2 C3 C4 C5 C6
A1 -80 90 -6 -5.4 -8.0 5
A2 -65 58 -2 -9.7 -1.0 1
A3 -83 60 -4 -7.2 -4.0 7
A4 -40 80 -10 -7.5 -7.0 10
A5 -52 72 -6 -2.0 -3.0 8
A6 -94 96 -7 -3.6 -5.0 6
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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pL - metric value can be computed as follows:
pJ
j
p
jj
jjp
jpmM
affwaL
1
1
)()(
*
Parameters that are required for the computation of pL - metric value are: maximum,
minimum and ideal value for each criterion, weight of each criterion and parameter p. These
parameters are presented in Table 3.
Table 3. Parameters required for computation of pL - metric value
Parameters
required for
each criterion
Notation C1 C2 C3 C4 C5 C6
Maximum
value jM -40.00 96.00 -2.00 -2.00 -1.00 10.00
Minimum
value jm -94.00 58.00 -10.00 -9.70 -8.00 1.00
Ideal value *
jf -40.00 96.00 -2.00 -2.00 -1.00 10.00
Weights jw 1 1 1 1 1 1
Normalized*
weights jw 0.1666 0.1666 0.1666 0.1666 0.1666 0.1666
* Since there are six criteria of equal importance, normalized weight of each criterion is 1/6
i.e., 0.1666 each.
pL - metric value of alternative A1 i.e., pL ( A1) is computed [on the basis of equation (2),
Table 2 and Table 3] as below:
Criterion C1 =
p
p
))00.94(00.40(
))00.80(00.40(1666.0 =
p1234074.0
Criterion C2 =
p
p
)00.5800.96(
)00.9000.96(1666.0 =
p02630526.0
Criterion C3 =
p
p
))00.10(00.2(
))00.6(00.2(1666.0 =
p0833.0
Criterion C4 =
p
p
))70.9(00.2(
))4.5(00.2(1666.0 =
p07356364.0
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Criterion C5 =
p
p
))00.8(00.1(
))00.8(00.1(1666.0 = p1666.0
Criterion C6 =
p
p
)00.100.10(
)00.500.10(1666.0 = p09255556.0
For alternative A1, pL - metric value for given p is
ppppppp
1
09255556.01666.007356364.00833.002630526.01234074.0
For p = 1 , 1L (A1) is as follows:
1
1
09255556.01666.007356364.00833.002630526.01234074.0 = 0.56573
For p = 2 , 2L (A1) is as follows:
2
1222222 09255556.01666.007356364.00833.002630526.01234074.0 =0.25415
For p = 10 (approximating for ), 10L (A1) is as follows:
10
1101010101010 09255556.01666.007356364.00833.002630526.01234074.0 =
0.16748
Similarly pL - metric values for other alternatives are computed. Best alternative is the one
which is having minimum pL - metric value from ideal solution. Accordingly ranking of
alternatives is done. Table 4 presents pL - metric values of alternatives A1 to A6 and
corresponding ranking pattern (values in parenthesis).
Table 4. pL - metric values and corresponding ranking pattern
Alternative p = 1 p = 2 p =
A1 0.56573 (4) 0.25415 (3) 0.16748 (4)
A2 0.57693 (6) 0.29869 (6) 0.18595 (6)
A3 0.57159 (5) 0.25512 (4) 0.16087 (2)
A4 0.49855 (3) 0.25929 (5) 0.17034 (5)
A5 0.31017 (1) 0.15171 (1) 0.10620 (1)
A6 0.47459 (2) 0.23311 (2) 0.16682 (3)
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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It is observed that for p = 1, alternatives A5, A6,A4, A1 , A2, A3 occupied ranks 1 to 6. For p =
2, these are A5, A6, A1, A3 , A4, A2 whereas for p = , these are A5, A3, A6, A1 , A4, A2. It
is observed that first position is occupied by A5 for all the three scenarios of p = 1, 2, .
PROMETHEE-2
PROMETHEE-2 (Preference Ranking Organisation METHod of Enrichment
Evaluation) is a MCDM method of outranking nature. The method is based on preference
function approach. Mathematically, preference function ),( baPj depends on the pairwise
difference jd between the evaluations )(af j and )(bf j of alternatives a and b for criterion
j, chosen criterion function and corresponding parameters (here criterion and criterion
function are different). Six types of criterion functions are listed in Table 5. Similarly
parameter jq represents indifference threshold that represents the largest difference that is
considered negligible by the decision maker when comparing two alternatives on that
criterion; parameter jp represents the smallest difference that justifies a strict preference for
one of the two alternatives. Mathematical analysis of preference function and its relationship
with jd for various criterion functions are also presented in Table 6. Multicriterion
Preference Index, ),( ba , a weighted average of the preference functions ),( baPj for all the
criterion is defined as:
J
jj
j
J
jj
w
baPw
ba
1
1
),(
),( (3)
)1(
),(
)(N
ba
a A (4)
)1(
),(
)(N
ab
a A
(5)
)()()( aaa (6)
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Table 5. Types of various criterion functions and relevant preference function values in
PROMETHEE-2
Types of generalized criterion functions Preference function values for various types
of criterion functions
1 Usual
criterion
01
00)(
j
j
jdif
difdH
2 Quasi
criterion
jj
jj
jqdif
qdifdH
1
0)(
3
Criterion with
linear
preference
and no
indifference
area
jj
jj
j
j
j
pdif
pdifp
d
dH
1
)(
4 Level
criterion
jj
jjj
jj
j
pdif
pdqif
qdif
dH
1
5.0
0
)(
5
Criterion with
linear
preference
and
indifference
area
jj
jjj
jj
jj
jj
j
pdif
pdqifqp
qd
qdif
dH
1
)(
)(
0
)(
6 Gaussian
criterion
]1[)(2'
2
2 j
jd
j edH
The value of '
j is the distance between
the origin and the point of inflexion of the
considered preference function.
where jw = Weight assigned to the criterion j; )(a = Outranking index of a in the
alternatives set N ; )(a = Outranked index of a in the alternatives set N ; )(a = Net
ranking of a in the alternatives set N ; J = Number of criteria. The alternative having the
H (d j)
d j
1
H (d j)
1
q j d j
H (d j)
1
p j d j
H (d j)
1
d j
0.5
-p j -q j q j p j
H (d j)
1
d j -p j -q j q j p j
1
d j - ‘j
‘j
H (d j)
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Yes
highest )(a value is considered to be the best/suitable. Figure 3 presents flow chart of the
PROMETHEE-2 methodology.
Figure 3 Flow chart of PROMETHEE-2 methodology
Start
Enter number of alternatives, criteria, payoff matrix, weight of each criterion
Compute pairwise difference between values of alternatives for each criterion ( )jd
Choose type of criterion function, indifference and/or preference threshold values for
each criterion.
Compute preference function matrix for each criterion based on jd and type of
chosen criterion function
Compute Multicriterion Preference Index
Compute net value for each alternative and corresponding rank
Select the best/suitable alternative having highest net value
Any need to specify another set of parameters
Print results
Stop
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Example
Compute ranking pattern of alternatives for the payoff matrix presented in Table 1 using
PROMETHEE-2 method. Parameters required for the method are presented in Table 6.
Assume equal weights for each criterion.
Table 6 Parameters required for PROMETHEE-2 method
Criteria Type Criterion function Parameters (thresholds) Normalized
weights
of the criterion
C1 2 Quasi criterion Indifference jq = 10 0.1666
C2 3 Linear preference
and no indifference
area
Preference jp = 30 0.1666
C3 5 Linear preference
and indifference
area
Indifference jq = 0.50
Preference jp = 5.00
0.1666
C4 4 Level criterion Indifference jq = 1.00
Preference jp = 6.00
0.1666
C5 1 Usual criterion _______ 0.1666
C6 6 Gaussian criterion '
j = 5.00 0.1666
Solution:
Table 2 is reproduced here as Table 7.
Table 7 Transformed payoff matrix
Crit.
Alt.
C1 C2 C3 C4 C5 C6
A1 -80 90 -6 -5.4 -8.0 5
A2 -65 58 -2 -9.7 -1.0 1
A3 -83 60 -4 -7.2 -4.0 7
A4 -40 80 -10 -7.5 -7.0 10
A5 -52 72 -6 -2.0 -3.0 8
A6 -94 96 -7 -3.6 -5.0 6
Solution methodology of PROMETHEE-2 is divided into various steps for the computation
of net and ranking pattern as explained below (Analysis is performed for maximization and
accordingly right hand side portion of Table 5 i.e., after H(dj) function mark is considered).
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Step 1: Pairwise difference between values of alternatives for criteria
Pairwise difference between values of alternatives for each criterion (six in this case) is to be
performed. For example, for criterion C1, pairwise difference between alternatives A1 and A2
are -80-(-65) = -15. Similarly pairwise difference between alternatives A2 and A1 for C1 are -
65- (-80) = 15. Pairwise difference between alternative A1 versus A1 is zero as they are
comparing the same i.e., alternative A1 versus A1. Table 8 (a) to Table 8 (f) present pairwise
differences between alternatives for criterion C1 to C6.
Table 8 (a) Pairwise difference matrix and preference function values for C1: Man power
(Quasi criterion function; jq = 10)
Alt. A1 A2 A3 A4 A5 A6
A1 0
(0)
-15
(0)
3
(0)
-40
(0)
-28
(0)
14
(1)
A2 15
(1)
0
(0)
18
(1)
-25
(0)
-13
(0)
29
(1)
A3 -3
(0)
-18
(0)
0
(0)
-43
(0)
-31
(0)
11
(1)
A4 40
(1)
25
(1)
43
(1)
0
(0)
12
(1)
54
(1)
A5 28
(1)
13
(1)
31
(1)
-12
(0)
0
(0)
42
(1)
A6 -14
(0)
-29
(0)
-11
(0)
-54
(0)
-42
(0)
0
(0)
Table 8 (b) Pairwise difference matrix and preference function values for C2: Power (Linear
preference and no indifference area; jp = 30)
Alt. A1 A2 A3 A4 A5 A6
A1
0
(0)
32
(1)
30
(1)
10
(0.3333)
18
(0.6)
-6
(0)
A2
-32
(0)
0
(0)
-2
(0)
-22
(0)
-14
(0)
-38
(0)
A3 -30
(0)
2
(0.0667)
0
(0)
-20
(0)
-12
(0)
-36
(0)
A4 -10
(0)
22
(0.7333)
20
(0.6667)
0
(0)
8
(0.2667)
-16
(0)
A5
-18
(0)
14
(0.4667)
12
(0.4)
-8
(0)
0
(0)
-24
(0)
A6 6
(0.2)
38
(1)
36
(1)
16
(0.5333)
24
(0.8)
0
(0)
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
D Nagesh Kumar, IISc, Bangalore
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Table 8 (c) Pairwise difference matrix and preference function values for C3: Construction
cost (109 $) (Linear preference and indifference area jq = 0.50; jp = 5.00)
Alt. A1 A2 A3 A4 A5 A6
A1
0
(0)
-4
(0)
-2
(0)
4
(0.7778)
0
(0)
1
(0.1111)
A2
4
(0.7778)
0
(0)
2
(0.3333)
8
(1)
4
(0.7778)
5
(1)
A3 2
(0.3333)
-2
(0)
0
(0)
6
(1)
2
(0.3333)
3
(0.5556)
A4 -4
(0)
-8
(0)
-6
(0)
0
(0)
-4
(0)
-3
(0)
A5
0
(0)
-4
(0)
-2
(0
4
(0.7778)
0
(0)
1
(0.1111)
A6 -1
(0)
-5
(0)
-3
(0)
3
(0.5556)
-1
(0)
0
(0)
Table 8 (d) Pairwise difference matrix and preference function values for C4: Maintenance
cost (109 $) (Level criterion jq = 1.00; jp = 6.00)
Alt. A1 A2 A3 A4 A5 A6
A1
0
(0)
4.3
(0.5)
1.8
(0.5)
2.1
(0.5)
-3.4
(0)
-1.8
(0)
A2
-4.3
(0)
0
(0)
-2.5
(0)
-2.2
(0)
-7.7
(0)
-6.1
(0)
A3 -1.8
(0)
2.5
(0.5)
0
(0)
0.3
(0)
-5.2
(0)
-3.6
(0)
A4 -2.1
(0)
2.2
(0.5)
-0.3
(0)
0
(0)
-5.5
(0)
-3.9
(0)
A5
3.4
(0.5)
7.7
(1)
5.2
(0.5)
5.5
(0.5)
0
(0)
1.6
(0.5)
A6 1.8
(0.5)
6.1
(1)
3.6
(0.5)
3.9
(0.5)
-1.6
(0)
0
(0)
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
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Table 8 (e) Pairwise difference matrix and preference function values for C5: Number of
villages to be evacuated (Usual criterion)
Alt. A1 A2 A3 A4 A5 A6
A1
0
(0)
-7
(0)
-4
(0)
-1
(0)
-5
(0)
-3
(0)
A2
7
(1)
0
(0)
3
(1)
6
(1)
2
(1)
4
(1)
A3 4
(1)
-3
(0)
0
(0)
3
(1)
-1
(0)
1
(1)
A4 1
(1)
-6
(0)
-3
(0)
0
(0)
-4
(0)
-2
(0)
A5
5
(1)
-2
(0)
1
(1)
4
(1)
0
(0)
2
(1)
A6 3
(1)
-4
(0)
-1
(0)
2
(1)
-2
(0)
0
(0)
Table 8 (f) Pairwise difference matrix and preference function values for C6: Security level
(Gaussian criterion: '
j = 5.00)
Alt. A1 A2 A3 A4 A5 A6
A1
0
(0)
4
(0.2739)
-2
(0)
-5
(0)
-3
(0)
-1
(0)
A2
-4
(0)
0
(0)
-6
(0)
-9
(0)
-7
(0)
-5
(0)
A3 2
(0.0769)
6
(0.5132)
0
(0)
-3
(0)
-1
(0)
1
(0.0198)
A4 5
(0.3935)
9
(0.8021)
3
(0.1647)
0
(0)
2
(0.0769)
4
(0.2739)
A5
3
(0.1647)
7
(0.6247)
1
(0.0198)
-2
(0)
0
(0)
2
(0.0769)
A6 1
(0.0198)
5
(0.3935)
-1
(0)
-4
(0)
-2
(0)
0
(0)
Step 2: Exploring preference function values for criteria C1 to C6 (on the basis of Figure 3,
Tables 6 and 7) : Sample calculations are presented below with reference to A1 and A2:
Criterion C1: Type 2: Quasi criterion function; Indifference threshold jq = 10
Pairwise difference between alternatives A1 and A2 for criterion C1 are -80-(-65) = -15. For
quasi criterion function, with indifference threshold value of 10, preference function value
P1(A1, A2) = 0 (as -15 ).10 Here P1 () represents for criterion C1 . Similarly difference for
alternatives A2 and A1 are -65-(-80) = 15 and corresponding preference function value P1(A2,
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
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A1) = 1 (15 ).10 In case of Quasi criterion function, elements of preference function matrix
are either 0 or 1.
Criterion C2: Type 3: Linear preference and no indifference area; preference threshold jp =
30
Pairwise difference between alternatives A1 and A2 for criterion C2 is 90-58 = 32 and
corresponding preference function value P2(A1, A2) is 1 (as 32 ).30 Similarly for A2 to A1
pairwise difference is -32 and corresponding P2(A2,A1) = 0. In case of Linear preference and
no indifference area criterion function, elements of preference function matrix vary between
0 and 1.
Criterion C3: Type 5: Linear preference and indifference area; Indifference threshold jq =
0.50; Preference threshold jp = 5.00
Pairwise difference between alternatives A1 and A2 for criterion C3 is -6-(-2) = - 4 and
corresponding preference function value P3(A1, A2) is 0 (as -4 ).5.0 Similarly for A2 to A1
pairwise difference is 4 (greater than jq value of 0.5 and less than jp value of 5) and
corresponding P3(A2,A1) is computed as (4-0.5)/(5-0.5) = 0.7778. In case of Linear
preference and indifference area criterion function, elements of preference function matrix
vary between 0 and 1.
Criterion C4: Type 4: Level criterion; Indifference threshold jq = 1.00; Preference threshold
jp = 6.00
Pairwise difference between alternatives A1 and A2 for criterion C4 is -5.4-(-9.7) = 4.3. As
pairwise difference is 4.3 (greater than jq value of 1.00 and less than jp value of 6), and
corresponding preference function value P4(A1, A2) = 0.5. In case of Level criterion, elements
of preference function matrix take values either 0, 0.5 or 1.
Criterion C5: Type 1: Usual criterion
Pairwise difference between alternatives A1 and A2 for criterion C5 is -8-(-1) = -7 and
corresponding preference function value P5(A1, A2) is 0 (as -7 ).0 Similarly for A2 to A1
pairwise difference is 7 and corresponding preference function value P5(A2, A1) is taken as 1.
In case of Usual criterion function, elements of preference function matrix are either 0 or 1.
Criterion C6: Type 6: Gaussian criterion '
j = 5.00
Pairwise difference between alternatives A1 and A2 for criterion C6 is 5-1 = 4 and
corresponding preference function value P6(A1, A2) is 0.2739. Similarly pairwise difference
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
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between A2 and A1 is -4 and preference function value P6(A2, A1) = 0.0. In case of Gaussian
criterion function, elements of preference function matrix vary between 0 and 1.
Table 9 (a) to 9 (f) present the preference function values for criteria C1 to C6 (values in
parenthesis) corresponding to pairwise difference matrices of C1 to C6.
Step 3: Computation of Multicriterion Preference Index (based on equation 3)
Multicriterion Preference Index, ),( 21 AA for pairwise alternatives (A1,A2) is computed as
follows:
Preference function values for A1 and A2 for criterion C1 to C6 are 0, 1.0, 0, 0.5, 0, and
0.2739. Corresponding weights of criteria are 1, 1, 1, 1, 1, 1 (or normalized weights of the
criteria are 0.1666 each). Substitution in equation (3) yields,
),( 21 AA = 2956.06
7739.1
]111111[
12739.01015.0101110
Similarly, ),( 12 AA 4630.06
7778.2
]111111[
10111017778.01011
Table 9 presents Multicriterion Preference Index values.
Table 9 Multicriterion Preference Index values
Alt. A1 A2 A3 A4 A5 A6
A1 0 0.2956 0.2500 0.2685 0.1000 0.1852
A2 0.4630 0 0.3889 0.3333 0.2963 0.5000
A3 0.2350 0.1800 0 0.3333 0.0556 0.4292
A4 0.3989 0.5059 0.3052 0 0.2239 0.2123
A5 0.4441 0.5152 0.4866 0.3796 0 0.4480
A6 0.2866 0.3989 0.2500 0.4315 0.1333 0
Step 4: Computation of (as per equation 4)
(A1) = 2199.05
1852.01000.02685.02500.02956.00
Step 5: Computation of (as per equation 5)
(A1) = 3655.05
2866.04441.03989.02350.04630.00
Step 6: Computation of net (as per equation 6)
Net (A1) = (A1) - (A1) = 0.2199 - 0.3655 = -0.1456
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
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M9L3
Similarly , ,net values for other alternatives are computed. The best alternative is
the one which is having the highest net value. Accordingly, ranking of alternatives is done.
Table 10 presents , , net and corresponding ranking pattern of each alternative.
Table 10. , , and ranking pattern for alternatives
Alt. Rank
A1 0.2199 0.3655 -0.1456 6
A2 0.3963 0.3791 0.0172 2
A3 0.2466 0.3362 -0.0896 5
A4 0.3293 0.3493 -0.0200 3
A5 0.4547 0.1618 0.2929 1
A6 0.3001 0.3549 -0.0548 4
It is observed from Table 10 that ranking pattern in the order of alternatives A1 to A6 is 6, 2,
5, 3, 1, 4 and alternative A5 with the highest net value of 0.2929 is considered as the best.
WEIGHTED AVERAGE METHOD
Weighted Average method is a utility type MCDM method. It is expressed as the average of
the weighted sum of criterion values i.e., jja uwuwuwU .......2211 where aU is the
overall utility value for alternative a; jwww ......,, 21 are the weights assigned to the criterion
and juuu ,.....,, 21 are the corresponding criteria values. The alternative having the highest
overall utility is considered the best. Suitable normalization approach can be used wherever
necessary.
Example
Compute priority of alternatives for the payoff matrix presented in Table 11 using Weighted
Average method. Assume weights for each criterion are 0.1, 0.12, 0.15, 0.20, 0.33, 0.1. Use
normalization method 4 for analysis.
Water Resources Systems Planning and Management: Advanced Topics – Multi-criteria Decision Making
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Table 11 Payoff matrix
Crit.
Alt. C1 C2 C3 C4 C5 C6
A1 8 9 6 5 2 4
A2 6.5 5.8 2 9 6 3
A3 8.3 6 4 7 4 4
A4 4 8 8 7 3 8
A5 5.2 7.2 4 2 1 6
A6 9.4 9 6 3.2 2 4
Solution:
Normalization of payoff matrix presented in Table 11 is performed using the formula
N
aj
j
af
af
1
2)(
)( and presented in Table 12.
Normalized weights of the criterion = 0.1, 0.12, 0.15, 0.20, 0.33, 0.1
Table 12. Normalized payoff matrix and weighted average values
Alt.
Normalized values of criterion Weighted
average
value
Rank
C1 C2 C3 C4 C5 C6
A1 0.45693 0.48281 0.45750 0.33846 0.23905 0.31923 0.35075 4
A2 0.37125 0.31115 0.15250 0.60922 0.71714 0.23943 0.47978 1
A3 0.47406 0.32187 0.30500 0.47384 0.47809 0.31923 0.41624 3
A4 0.22846 0.42917 0.60999 0.47384 0.35857 0.63847 0.44279 2
A5 0.29700 0.38625 0.30500 0.13538 0.11952 0.47885 0.23620 6
A6 0.53689 0.48281 0.45750 0.21661 0.23905 0.31923 0.33438 5
Weighted average of alternative A1 is computed as follows:
jjA uwuwuwU .......22111 i.e.,
35075.031923.01.023905.033.0
33846.02.045750.015.048281.012.045693.01.0(1AU
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M9L3
Similarly weighted average values for other alternatives are computed. The best alternative is
the one which is having the highest weighted average value. Accordingly ranking of
alternatives is done. Table 12 presents the weighted average values of alternatives and
corresponding ranking pattern. It is observed that the ranking pattern in the order of
alternatives A1 to A6 is 4, 1, 3, 2, 6, 5. It is observed that A2 and A4 occupied first and second
positions due to their higher utility values of 0.47978 and 0.44279.