6 Drinking Water Supply Systems—Evolution Towards Efficiency
213
However, during the last decade, in order to fight corruption and to ensure a clean
and transparent decision-making process, new approaches were adopted. For example, multi-criteria decision making (MCDM) or multi-criteria decision aid (MCDA)
is a discipline aimed at supporting decision makers when faced with numerous and
sometimes conflicting evaluations. MCDA manages to highlight the complexity of
those irreconcilable variables and provide a way to come to a “best” compromise, in
a transparent process.
Application of these methods generally require the following steps [7]:
– choice of a set of possible options (alternatives);
– creation or acquisition of attributes/criteria that are applied to all identified options;
– allocation of scores that reflect the impact or “weight” of each attribute/criterion.
There are many MCDA/MCDM methods in use today. They are not “miracle”
tools, in the sense that sometimes, each decision maker has to feed them with subjective information. Therefore, the results are not always unique because they are
dependent on decision maker’s preferences. If the results are arguable, new scenarios
may be taken into account, by negotiating on those preferences.
The American school uses the full aggregation approach: “a score is evaluated
for each criterion, and these are then synthesized into a global score. This approach
assumes compensable scores, i.e. a bad score on one criterion is compensated for by
a good score on another” [11].
The French school uses the outranking approach: a bad score may not be compensated for by a better score. The order/rank of the alternatives may be partial because
the notion of incomparability is allowed. Two alternatives may have the same score,
but their behavior may be different, and therefore they remain incomparable [11].
From the multitude of MCDA methods available, the Electre 1 method (French
school) was preferred for our choice problem: the selection of the water pipe material.
The ELECTRE acronym comes from the French “Elimination Et Choix Traduisant
la Realité”, which means elimination and choice expressing the reality [9].
Electre 1 follows a partial aggregation procedure, using the outranking relationship as a basis, together with concordance and discordance indexes and finally with
sensitivity analysis. The method is based on a pairwise comparison of alternatives,
done systematically, criterion by criterion, following the Condorcet principle (seen
as a milestone for the outranking theory):
An action X outranks an action Y when X is at least as good as Y with respect to the majority
of criteria, without being substantially less good than Y with respect to the other criteria.
[15]
Therefore, the hypothesis “X outranks Y” involves simultaneously a concordance
condition and a non-discordance condition.
We applied the Electre 1 method for a typical situation when the water operator
had to choose “the best” type of pipe material among five competitors:
– Polyvinyl chloride pipe (PVC);
– Steel pipe, spirally welded (STSW);
213
However, during the last decade, in order to fight corruption and to ensure a clean
and transparent decision-making process, new approaches were adopted. For example, multi-criteria decision making (MCDM) or multi-criteria decision aid (MCDA)
is a discipline aimed at supporting decision makers when faced with numerous and
sometimes conflicting evaluations. MCDA manages to highlight the complexity of
those irreconcilable variables and provide a way to come to a “best” compromise, in
a transparent process.
Application of these methods generally require the following steps [7]:
– choice of a set of possible options (alternatives);
– creation or acquisition of attributes/criteria that are applied to all identified options;
– allocation of scores that reflect the impact or “weight” of each attribute/criterion.
There are many MCDA/MCDM methods in use today. They are not “miracle”
tools, in the sense that sometimes, each decision maker has to feed them with subjective information. Therefore, the results are not always unique because they are
dependent on decision maker’s preferences. If the results are arguable, new scenarios
may be taken into account, by negotiating on those preferences.
The American school uses the full aggregation approach: “a score is evaluated
for each criterion, and these are then synthesized into a global score. This approach
assumes compensable scores, i.e. a bad score on one criterion is compensated for by
a good score on another” [11].
The French school uses the outranking approach: a bad score may not be compensated for by a better score. The order/rank of the alternatives may be partial because
the notion of incomparability is allowed. Two alternatives may have the same score,
but their behavior may be different, and therefore they remain incomparable [11].
From the multitude of MCDA methods available, the Electre 1 method (French
school) was preferred for our choice problem: the selection of the water pipe material.
The ELECTRE acronym comes from the French “Elimination Et Choix Traduisant
la Realité”, which means elimination and choice expressing the reality [9].
Electre 1 follows a partial aggregation procedure, using the outranking relationship as a basis, together with concordance and discordance indexes and finally with
sensitivity analysis. The method is based on a pairwise comparison of alternatives,
done systematically, criterion by criterion, following the Condorcet principle (seen
as a milestone for the outranking theory):
An action X outranks an action Y when X is at least as good as Y with respect to the majority
of criteria, without being substantially less good than Y with respect to the other criteria.
[15]
Therefore, the hypothesis “X outranks Y” involves simultaneously a concordance
condition and a non-discordance condition.
We applied the Electre 1 method for a typical situation when the water operator
had to choose “the best” type of pipe material among five competitors:
– Polyvinyl chloride pipe (PVC);
– Steel pipe, spirally welded (STSW);