Page 132 - Special Topic Session (STS) - Volume 4

STS571 Jaanus Kroon
• The duration of a visit is determined from the temporal distribution of
the call operations of an individual mobile phone. If all the call activities
are within a single day, the recorded duration of the visit is one day. If
there are call activities on several days, the number of the days with call
activities and any ‘empty’ days in between is assumed to be the number
of days of the visit. If there are no call activities for seven consecutive
days, the person is assumed to have left the country. For outbound
travel, all the visits are compared against the activities in the same period
in Estonia, and if necessary the initial visit is split into several visits.
Data processing broadly consists of the following steps, some of which are
country-specific:
• Quality control of the data collected from the operator’s system. Since
there is a huge amount of data, filters have been developed to find and
correct errors based on data characteristics.
• Filtering and evaluation of the roaming data in order to ensure
representativeness and quality of data.
• Geographical and temporal interpolation, i.e. linking additional
parameters to ensure administrative and chronological comparability.
• Elimination of border bias:
o the registration of the roaming activities by Estonian residents who
are incidentally in the coverage area of foreign mobile operators or
o the registration of the roaming activities of the customers of foreign
mobile operators who are incidentally in the coverage area of mobile
phone masts located near Estonian borders, such as ships’ crews and
passengers on passing ships, or residents of the neighbouring
countries.
• Elimination of transit travel:
o For inbound travel, travellers detected in Estonia’s main transit
corridors if the stay in Estonia is shorter than a certain limit; there are
10 such transit areas, including the Tallinn-Ikla and Tallinn-Narva
roads and the Estonian section of the Riga-Pskov road, Tallinn
Airport, and the major ports.
o For outbound travel, trips through foreign countries. Countries
visited without an overnight stay, which do not comply with the
criteria of a destination country, are classified as transit countries.
One of the criteria for determining visiting and transit countries is
the distance from Estonia and the length of stay in hours.
• Profiling and segmenting of individual trips for single-day and multiday
visitors; the number of visits to and from the country, the country of
origin (inbound) and destination (outbound) and the number of nights
and days spent are calculated. Certain exceptions apply to long-term
students and border workers:

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