In this method, the experts do not assemble at all, and individual estimates are
circulated on paper, rather than orally, thus preventing any body from dictating the
group or any possible conflict among them.
In practice, the results of the Delphi method depends on the calibre of the experts
involved, their aptitude to echo societal values and the way the process is carried out.
8.8.7 The Limitations of Contingent Valuation
Surveys are, theoretically, conjectural. On top of this, few people are skilled in
taking unambiguous decisions related to the value or price of environmental services
or goods. Therefore, given that the CV methods do not investigate genuine behaviour, it is likely that the simulation of real world circumstances might leave a doubt
on the accuracy of the methods used. There are several types of biases which could
influence the reliability of the method and the results.
Among others, an information bias can arise either if too little information is
given about the possibilities or if the interviewer provides misleading statements.
Ideally, survey participants should be given clear, complete and unbiased details
about the choices.
8.9 Macroeconomic Models
Infrastructure projects often disturb the neighbourhood environment in terms of
quality and resource sustainability, but also influence the region around the project
site. In such conditions, it is necessary to determine costs and benefits over a larger
area. From this perspective, models involving general equilibrium and systemsanalysis may avoid the problems which require considering environmental and
secondary economic impacts.
8.9.1 Generalised Input-Output Models
The generalised input-output (I-O) analysis is one, among many methods, of incorporating the consequences of development activity impacting the economy and the
environment, in the analysis.
Input-output analysis uses the interactions of production activities in modern
economic systems. Each production activity behaves in two ways:
1. it provides its output to other industries and to final buyers.
2. it purchases inputs: land, natural resources, imported materials, capital services,
labour skills, managerial expertise and the production from other industries.
8.9 Macroeconomic Models
237
circulated on paper, rather than orally, thus preventing any body from dictating the
group or any possible conflict among them.
In practice, the results of the Delphi method depends on the calibre of the experts
involved, their aptitude to echo societal values and the way the process is carried out.
8.8.7 The Limitations of Contingent Valuation
Surveys are, theoretically, conjectural. On top of this, few people are skilled in
taking unambiguous decisions related to the value or price of environmental services
or goods. Therefore, given that the CV methods do not investigate genuine behaviour, it is likely that the simulation of real world circumstances might leave a doubt
on the accuracy of the methods used. There are several types of biases which could
influence the reliability of the method and the results.
Among others, an information bias can arise either if too little information is
given about the possibilities or if the interviewer provides misleading statements.
Ideally, survey participants should be given clear, complete and unbiased details
about the choices.
8.9 Macroeconomic Models
Infrastructure projects often disturb the neighbourhood environment in terms of
quality and resource sustainability, but also influence the region around the project
site. In such conditions, it is necessary to determine costs and benefits over a larger
area. From this perspective, models involving general equilibrium and systemsanalysis may avoid the problems which require considering environmental and
secondary economic impacts.
8.9.1 Generalised Input-Output Models
The generalised input-output (I-O) analysis is one, among many methods, of incorporating the consequences of development activity impacting the economy and the
environment, in the analysis.
Input-output analysis uses the interactions of production activities in modern
economic systems. Each production activity behaves in two ways:
1. it provides its output to other industries and to final buyers.
2. it purchases inputs: land, natural resources, imported materials, capital services,
labour skills, managerial expertise and the production from other industries.
8.9 Macroeconomic Models
237