B.5. Mobile phone records
10.34. The present Guide encourages compilers to consider employing mobile phone applications (“apps”) to collect information about mobile phone users’ movements and behaviours. Such apps can easily be downloaded to users’ devices and can retrieve information to enable data analysts to conduct very detailed studies of users’ movements and behaviours. It is advised that compilers clearly request the consent of mobile phone users before using such apps and describe how the data will be used for official statistical purposes.
10.35. For all types of mobile phone data, compilers must take precautions to make the data anonymous and check that confidentiality rules are being applied appropriately. Privacy concerns are of critical importance and compilers should reassure users that the data will be used only for official purposes and will be aggregated to maintain confidentiality. Again, as recommended in chapter 2 of the present Guide, legal acts on the confidentiality of official statistics should be well-established.
10.36. Compilers will likely need to adjust the mobile phone data to correspond with the definitions of official statistics. It is recommended that algorithms be developed to automatically organize the data according to statistical definitions as much as possible.
10.37. It is further advised that the residency of a mobile phone user be determined by the residency of the mobile operator associated with the user’s account.
10.38. Purpose and description The use of mobile phones is widespread in many countries, enabling statistical compilers to obtain data on location (geographical coordinates in time) and other important indicators about mobile phone users and their activities.
10.39. Data gathered with the help of mobile phones can be divided into active and passive positioning data. In the case of active positioning, the collector of the statistics contacts phone owners and asks for information about their location, themselves and their behavior (e.g. about their travel). In the case of passive mobile positioning, data are automatically stored in the memory files of phone operators or other recording systems.
10.40. Using mobile phone records for purposes of statistics on the international supply of services Both active and passive positioning data obtained from mobile phone records can be important sources for statistics on the international supply of services. In particular, mobile phone records are advantageous in the compilation of the travel item and mode 4 services, as information on the country of residence and current location of the mobile phone user facilitates the identification of international travellers, and, possibly, providers of mode 4 services.
10.41. Active mobile positioning In the case of active mobile positioning, information about the location of a phone, the user, the travel behaviour of the user and/or the provision of services is found by making special inquiries, which generally requires the consent of the individuals chosen to participate in the study. Active positioning is related to surveys and software that can be downloaded on smartphones. As a result, it is possible to obtain very accurate information about the movement, means of transport, expenses, provision of services and motivation of the chosen respondents. Active positioning data are geographically accurate. Such detailed data enable data collectors to analyze mobility within the destination, and to conduct market research for a particular region. More study is necessary on how to engage with mobile phone users; the involvement with users could range from merely turning on GPS with consent to providing answers actively on a regular basis. Those studies should cover the technical possibilities of phone applications, their user-friendliness and the incentives for users to participate. Of course, the treatment of the data should be transparent for users who provide the active mobile phone data. Recruitment of mobile phone users for outbound travel could be more difficult and more costly owing to the different standards of foreign operators. Still, that area is a very important source for gathering more detailed statistics for studies on travel/tourism and the provision of mode 4 services.
10.42. Passive mobile positioning In the case of passive mobile positioning, statistical data are obtained from secondary sources of mobile phone use, which are most often the phone use information automatically recorded in the systems of operators, such as the call detail record (CDR), Erlang and anonymous bulk location data (ABLD), among others. The advantages of passive positioning is the huge mass of data involving all phone users and the relatively cost-effective data collection method. The shortcomings, however, are the difficulty of protecting the privacy of persons and obtaining the data from operators, as well as the lack of characteristics included in the data. The main convention for defining the residence of persons travelling is by the residence of the mobile operator related to them. Other conventions for other statistical purposes can be introduced as well. The use of passive positioning data in the area of travel/tourism is rapidly growing, because it is difficult to get an adequate overview of the movements and mobility of people in the increasingly mobile world with open borders.
10.43. The CDR is one of the most widely used sources among the passive positioning data suitable for the compilation of the travel item as well as for tourism statistics. The data are obtained from the data warehouse or from the billing records of the mobile network operator’s system, i.e., from the invoice through which information is gathered about phone users through such information as the time, location, duration and cost of a call. The production of statistics from such data requires standardizing the data and rendering it anonymous, as well as checking it, because the privacy of people and the business confidentiality of operators must be protected. CDRs are usually issued as impersonalized data, either aggregated for certain types of user groups or pseudonymously with randomly generated identifiers. Spatially, CDR data are usually issued with the accuracy of a network cell (the cell together with its location is called the cell global identity (CGI)). The level of accuracy is well suited, for example, to generating the main variables of tourism statistics, and several data collection systems using CDRs were developed for that purpose. CGI is, however, not accurate enough for preparing detailed analyses of the movements of persons. Rather, CGI can be used to identify visitors in transit through airports and seaports or on the main transit lines through the country. Moreover, there is noise in the roaming data, and travellers in the border areas of some countries may be picked up by the cells of neighboring countries even if they did not physically enter the country.
10.44. A caveat on the use of mobile phone records is that travellers who are in a country for a short period of time, for example, less than a year, may purchase local subscriber identity module (SIM) cards for their phones and thus not be covered through mobile phone records.
10.45. The methodology of preparing passive mobile positioning data requires adjusting the mobile data to correspond with the definitions of official statistics. For example, the duration of a visit, the number of nights spent and transit tourism are assessed on the basis of ordering single call activities, with the uneven distribution of call activities in time and space posing a methodological problem. For that reason, it is necessary to develop algorithms for organizing data, such as segmenting visitors and visits.