Identification of groundwater recharge potential zones using AHP …
147
N ormali zed W eight =
Eigenvector value o f a f eature class
Sum o f all the Eigenvectors
These normalized weights are then used for sorting the inputs for calculations
using HFL.
3.3.6 Checking for Consistency
Saaty’s eigenvector method is used to find out the consistency ratio (CR) for errors
in the judgment of parameter weights. CR is calculated using the formula:
C.R. =
C.I.
R.I.
(1)
where CI represents for consistency index, derived using the formula.
C.I. =
λ max − n
n − 1
(2)
and RI stands for ratio index, the value of which is specified by Saaty (Table 5),
where n is the number of parameters, hence 8.
If the value of CR is less than 0.1, then it is accepted, whereas for CR values
greater than 0.1, reconsideration of judgments is required. In our case, the CR value
is 0.035, which is well below the permissible limit.
Table 5 Saaty’s ratio index for different number of parameters (n)
n
R.I.
1
0
2
0
3
0.58
4
0.89
5
1.12
6
1.24
7
1.32
8
1.41
9
1.45
10
1.49
147
N ormali zed W eight =
Eigenvector value o f a f eature class
Sum o f all the Eigenvectors
These normalized weights are then used for sorting the inputs for calculations
using HFL.
3.3.6 Checking for Consistency
Saaty’s eigenvector method is used to find out the consistency ratio (CR) for errors
in the judgment of parameter weights. CR is calculated using the formula:
C.R. =
C.I.
R.I.
(1)
where CI represents for consistency index, derived using the formula.
C.I. =
λ max − n
n − 1
(2)
and RI stands for ratio index, the value of which is specified by Saaty (Table 5),
where n is the number of parameters, hence 8.
If the value of CR is less than 0.1, then it is accepted, whereas for CR values
greater than 0.1, reconsideration of judgments is required. In our case, the CR value
is 0.035, which is well below the permissible limit.
Table 5 Saaty’s ratio index for different number of parameters (n)
n
R.I.
1
0
2
0
3
0.58
4
0.89
5
1.12
6
1.24
7
1.32
8
1.41
9
1.45
10
1.49