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important to perform a comprehensive risk analysis
based on all datasets available. The best alternative
is to merge all datasets into a single dataset. A pre-
condition in the data merging process is that all vari-
ables must be compatible, i.e. they have to share
similar properties including variable type, number,
label, and value and measurement level. Variables
are not organized in any particular order in the data-
bases. Based on the SMA DB, variables are labelled
and organized in main categories (Table 1). A com-
plete data merging, which is merging all databases
including all cases and variables, is not possible.
Merging parts of datasets may be possible, but con-
siderable time, resources and expertise are required.
This process includes translation, codification and
de-codification and design and re-design of varia-
bles, conversion of data from Excel to SPSS data
format, data merging and filtering. One case history
is one A4 paper text (multiplied by ca 8000 inci-
dents) and many variables are string or text format
variables written in different languages. Text format
variables contain very important information. The
databases are mainly designed based on the DAMA
coding system, which was originally agreed (1990)
by Scandinavian countries for registration and anal-
ysis of marine incidents. The FMA DB and SMA
DB share more in common than the two other data-
bases. Deviations from the code and changes are al-
so observed within the same database (e.g. FMA
DB). The labels of many variables in the FMA DB
are coded according to the DAMA coding system.
These variables must be de-codified. The databases
are specially designed databases, which may be in-
convenient for converting data into advanced statis-
tical program formats. The data were sent to LU in
an Excel format. Data analyses and result presenta-
tions with this data format are limited. The present
Excel data format of the databases is not readily
convertible to the statistical program format. The da-
ta are organized on the “case” and “variable” bases.
It is unclear whether the case histories are compiled
on “event” or “ship” bases. In many cases, in a sin-
gle incident two or more ships have been involved.
The DMA DB is confined to a very limited number
of events such as collision, grounding and fire. In
one database, many cases were deleted. The SMA
DB and FMA DB contain incidents that have oc-
curred in the respective country territorial waters for
all nationalities and ships flying the respective coun-
try flag outside the territorial waters. Therefore, var-
iables should be designed for filtering or sampling
purposes. In terms of data properties and structure,
there are considerable discrepancies among the da-
tabases (Tables 2-6 and Figs 1-3). Only a very few
variables are compatible. There are significant gaps
in the number, category, type and measurement level
of variables. The string (Str.) and nominal (Nom.)
variables dominate (51-75%) all databases. The se-
cond largest numbers of variables are scale (Sc.) and
ordinal (Ord.) variables (10-38%). More analysis
methods are applicable to scale and ordinal variables
than nominal variables. The variables for measuring
risks of maritime transport of dangerous goods are
very limited, if not lacking for certain databases.
Table 1. The main categories and examples of variables in the
SMA DB (1985-2007).
__________________________________________________
Main category: examples of variables
__________________________________________________
Time: year, month, day, day of the week, time (hours)
Location: latitude and longitude, ports of departure and arrival,
country, geographical areas, traffic area, fairway etc.
Ship: call sign, name, type, class society, nationality, built, size
(dwt, brt, length), material etc.
Ship activity: ship activity (en-route, loading/discharging), ac-
tivity onboard etc.
Exposure: crew, passengers, visitors, total numbers etc.
Cargo: description, type, amount, dangerous goods etc.
Event: type, event grading, description
Cause: categories codified, description
Other: pilot presence onboard
Environment: light, visibility, precipitation, sea, wind etc.
Consequence: human (fatality, injury, disappearance – crew,
passengers, pilots, others, total), ship (damage – description,
location, extent), environment (oil and other pollutants – type,
amount)
__________________________________________________
Table 2. The categories, types and measurement levels of vari-
ables in the DMA DB (1997-2007).
_______________________________________________
Variable
Main category Type* Measurement level**
_______________ _________________
Str. Nrc. Date Other Nom. Ord. Sc. Other
_______________________________________________
Time 4 4
Location 1 2 3
Ship 6 2 6 2
Event 2 1 1
Cause 2 2
Other 1 1
Consequences 1 1 1 1
______________________________________________
Total 13 2 4 3 15 1 2 4
______________________________________________
* Variable type: Str. (String variables whose values are not
numeric and therefore are not used in calculations), Nrc. (Nu-
meric variables). ** Variable measurement level: Nom. (Nom-
inal variables whose values represent categories with no intrin-
sic ranking), Ord. (Ordinal variables whose values represent
categories with some intrinsic ranking), Sc. (Scale variables
whose values represent ordered categories with a metric)
(SPSS 16.0 for Windows 2007)
Table 3. The main categories, types and measurement levels of
variables in the FMA DB1 (1990-1996).
_______________________________________________
Variable
Main category Type* Measurement level**
_______________ _________________
Str. Nrc. Date Other Nom. Ord. Sc. Other
_______________________________________________
Time 5 5
Location 4 2 4 2
Ship 11 2 11 2
Ship activity 2 2
Exposure 2 2
Cargo 1 1 1 1
Event 3 3
Cause 4 4
Other 1 1