Jean-Paul Rodrigue (2013), New York:
Routledge, 416 pages.
The Specialization Index and the Location Coefficient
Author: Dr. Claude Comtois
1. The Specialization Index
In transport, to find out if a terminal is specialized in the transshipment
and/or handling of a particular kind of merchandise or if, inversely,
it transfers a wide variety of merchandise, we can calculate a specialization
index. For example, the index can be used to know if a port is specialized
in the handling of a certain type of product (e.g. containers) or if
it handles a wide range of merchandise. As a consequence, such an index
is quite versatile and has a variety of applications; it informs geographers
on the activities of any type of terminal (port, train and airport).
In the case of an airport terminal, one could ask if a given airport
deals with only a single type of flights/passengers (local, national,
international, etc.) or if it welcomes several. The specialization index
(SI) is calculated using the following formula:
which is the total of squares of tonnage (or monetary value) of each
type of merchandise i (ti) handled at a terminal over
the square of the total volume tonnage (or monetary value) of merchandise
handled at the terminal.
So, if the specialization index tends toward 1, such a result
indicates that the terminal is highly diversified. If, inversely,
the index tends toward 0, it means that the terminal's activity
is specialized. Thus, the specialization index is called upon
to appreciate the degree of specialization/diversification of a port,
an airport, a train station or any type of terminal.
2. The Location Coefficient
Certain kinds of merchandise are often transshipped at particular
terminals rather than at others. Thus, the degree of concentration of
a certain type of traffic in a terminal (port, airport, train station)
compared with the average for all the terminals, can be measured by
using the location coefficient.
The location coefficient is the share of traffic occupied
by a type of merchandise at a terminal over the share of traffic
of the same type of merchandise among the total traffic of all terminals
of the same type.
In the field of transportation, the location coefficient (LC) is
calculated by using the following formula:
Where Mti is the traffic of a merchandise t at
a terminal i, Mt is the total of all merchandises
of type t for all terminals and M is the total of
all types of merchandises for all terminals.
The greater the value of the index, the greater is the degree is
the degree of traffic of a certain type of merchandise. Possible outcomes
are of three types:
Beside using the location coefficient to evaluate the relative weight
of a type of traffic in a terminal to it, the location coefficient can
be used to appreciate the importance of an economic activity
for a community compared with the importance of the same activity within
a defined larger area (e.g.. province, country, world, etc.). The larger
geographic entity is also known as the benchmark and is critical in
the calculation of the location coefficient.
- A figure lower than 1, indicate that the traffic of the
chosen merchandise in the terminal is under-represented compared
to the same merchandise in all the terminals.
- A figure equal to 1, indicates that the quantity of traffic
of the chosen merchandise in a terminal is proportional to
its participation to total traffic.
- Finally a coefficient above 1 indicates that the traffic
of the chosen merchandise in a given terminal is preponderant
in total traffic.