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it can be said that the larger the amount of data available, the lower the uncertainty
behind the damage estimates is.

7.7.7.1 Goal and Scope Definition and Inventory Analysis
In the goal and scope definition, subjective elements exist in the form of the selection
of the functional unit, which implies whether benefits are (or are not) given for
avoided environmental loads. Moreover, the selection of the cut-off criteria for the
system boundaries and the dominance analysis can influence the outcome. It is only
possible to address these uncertainties and influences by sensitivity analysis and the
use of scenarios for the different options.
In the inventory analysis, the main types of uncertainties and variability analyzed
by Monte Carlo simulation in Chapter 5 are those referring to parameters, including
frequency of sampling, method of measurement (continuous on-line, or from time
to time by more or less sophisticated analytical methods) and homogeneity of fuels.
For the exactness of the modular process model, as for all process simulations, the
adequate estimation of physical properties that are not well established is crucial.
The estimations are taken from the publication of Kremer et al. (1998), so the quality
depends on the values proposed by these authors.

7.7.7.2 Dominance Analysis and Spatial Differentiation
The dominance analysis adds a level of uncertainty by reducing the media, environ-
mental loads and processes considered. However, it improves the relevance of the
remaining information for further assessment.
With respect to the spatial differentiation, it should be said that the area under
study, Catalonia, is rather small (compared to other administration units like Spain,
European Union, or the U.S.). Therefore, a statistical reasoning is per se limited due
to the restricted area. Therefore, the determination of class limits with respect to the
administrational units and settlement structure, and according to meteorological
conditions, must be done with special care.
The problem with choosing the outer boundaries of the classes (in this case
provinces and districts) is that information on dispersion conditions (wind speed)
as well as on the settlement structure (population density) is not always bound to
administrational units. Meteorological conditions are particularly subject to geo-
graphic situations such as topography or latitude, while administrational units are
generally linked to settlement structures. For instance, the district of Barcelonès
comprises the city of Barcelona with a few other municipalities and represents an
urban district in an agglomerated region.
However, not all district boundaries delimit the settlement structure that clearly.
For example, the Tarragonès district (central city in rural region) comprises the city
of Tarragona as well as rural municipalities, which contradicts the definition of each
class. Administrational units also depend on history and political decisions because
determination of the limits of the municipalities usually is not a recent decision.
Thus, the choice of administrational units is problematic in terms of how
representative settlement and dispersion conditions are. However, these limits are

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