Table 1: Groups of attribute types and some examples.
Group Example
Temporal position of accident Dates
Geographical location of accident Province
Injured characteristics Nationality
Modality of accident At workplace
Administrative data of accident Ref. Tables
Medical features of accident Compensation
Owner characteristics Ref. Tables
2.1.2 Reference Tables
As previously described, some reference tables are
published using the same methods for representing
the OD. There are three types of reference tables:
Simple tables: which represent all the values that
an attribute may assume;
Complex tables: which contain multi-level
structures;
Tables with intervals: which are used to evaluate
a parameter with respect to given ranges and
determine the right classification of the injured
2.1.3 Statistical Tables
The OD, available for occupational accidents, are
expressed in a fine granularity, indeed, each record
corresponds to a single accident.
Furthermore, as previously discussed, some
tables, that group the data on different
characteristics, are also published on the site. They
reflect the statistical results, which are considered of
the major impact for the public interest.
For example, a set of tables groups the accidents
on the basis of the modality and period of
occurrence, others deal with the fatality accidents.
3 THE ONTOLOGICAL MODEL
The OD, as illustrated above, are well organized and
structured data, mainly useful for developing
statistical analysis, also sophisticated. Due to their
fine granularity, diverse aggregate types can be
studied, further to those statistical tables already
available on the site.
On the other hand, the high specificity of the
domain (insurance of occupational accidents) with
the particular vocabulary adopted can arise some
difficulties for the interoperability with other
contexts. Indeed, for the current version of OD, the
interoperability is represented only with the
information related to NACE code, for defining the
occupational sectors, the Italian Provinces, for
describing where the event happened, and a
classification of Nations for identifying the
nationality of the injured.
What we have done is to define an ontology
starting from the OD and the vocabulary, rather than
model the domain of “occupational accidents” in
general. The figure 1 shows the overview of all the
concepts modelled into the ontology and their
relations, some of them will be described in more
details in the paragraphs §3.3 and §3.4.
The reason for this choice is that the domain of
“occupational accidents” is characterized by sub-
domains of diverse nature, such as management,
legal and medical assessment, and economical
evaluation. To model this domain starting from each
single sub-domain in a complete form would be a
very complex project, requiring the efforts of
different types of knowledge and expertise. Since
the data available are only those represented in the
OD, it seems that the maintaining the consistency
between the sets of data available and the domain of
knowledge would be more effective.
Furthermore, since the granularity of the OD, the
data contained can be considered the main and the
sufficient information, which describes the event
(accident). Probably, in order to define the
administrative process for evaluating accident cases,
an ontology fully devoted for covering all the
administration aspects would be required.
All the fields contained into the dataset represent
a result of the evaluation process of the accident,
however, other information, which are considered
during the evaluation phase, are actually out of
scope of the OD, such as the description of
cause/effect related to each case. The defined
ontology can be easily extended to model those new
concepts; this approach seems to be more feasible
rather than trying to describe a general ontology,
which covers all the aspects.
3.1 Definition Process
The design and development of an ontology may
follow different methodological approaches (Noy
and McGuinnes, 2001). In this research, both
bottom-up and top-down approaches have been
adopted, combining the two methods in an iterative
process.
Indeed, starting from the data (contained into the
OD and the reference tables) and the definitions
enclosed into the vocabulary, through a bottom-up
approach, it was pointed out the concepts and the
instances to be modelled.
The top-down approach has been adopted for
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