A. CASELLES proposes "a theoretical approach to all kinds of forecasting and control problems" considering "General Systems Theory…specially adequate to the most difficult ones" (1993, p. 1285-89)
Applying his proposal to technology assessment, he suggests a frame "to begin the identification process of the elements and connections involved… in each technology assessment case", as well as a mathematical model taking in account the following factors:
- Required services depending on population implicated and on unitary demand respect to each service;
- Population implicated (based on a demographic submodel);
- Unitary demand (for example, all urban transport made by private cars makes the unitary demand of street surface higher than when public transport is used);
- Effective capacity to produce services;
- Resources to services; an input variable that enters the resources distribution among services, made by managers;
- Resources required by each technology;
- Offered services (producing an income);
- Resources consumption and operation (which produce a cost)"
R. PETRELLA (Director of the Program "Forecasting and Assessment in Science and Technology" of the European Union) writes: "… Technology Assessment is the set of procedures and means at the disposal of a society for the understanding of the nature and impact of scientific mutations, development and uses of technologies and for research about their usefulness, their economical feasibility, their social relevance and value" (1993)
This confirms that assessment, specially in technological matters, is much more than a simple study of technical and economical adequacy of some innovation, confirming the usefulness of CASELLES' proposed systemic methodology.
However, his list of technical criteria should be expanded in order to take in account some other important aspects, as for instance: Costs of resources renewal , or impact of their exhaustion; impact on ecosystems; social benefits and costs; probable duration of usefulness, etc…
To make this clearer, CASELLES' criteria, if applied for example to the realization of the Kazakhstan irrigation scheme – which ruined the whole Aral Sea ecosystem and the human system depending on it – would have passed it with flying colors. The purely technical and economical criteria applied where wholly insufficient to predict possible side-effects of different types.