Collecting and processing data from mobile technologies

In the past decade or so, mobile technologies that can be used to track the movement of people, freight consignments, and passenger and freight vehicles have evolved rapidly. Initially, this paper reviews the major categories of such technologies, including mobile telephones, Global Positioning System (GPS) devices, Personal Data Assistants (PDAs), and the use of laptop computers and advanced communications systems. In reviewing these, the paper proposes a number of attributes for classification that are considered useful, both from the viewpoint of collecting data by these technological means, and also from the viewpoint of processing. The next section of the paper reviews what has been reported to date about the willingness of people to engage in such technologically-based surveys, and about any reported biases in the make up of the sample obtained, especially in comparison to the biases that are commonly found in more conventional paper and interview-based surveys. From this information, the paper draws lessons about the nature of the samples that can be achieved and the extent to which such samples may be considered either more or less representative of the populations from which they are drawn. The third main section of the paper addresses the issue of data processing. Of particular concern here is the processing requirements for logged data, where the technological device is capable of recording rather limited information about the travel undertaken, and processing software may need to impute other characteristics of the travel that are normally required for travel analysis. A common thread for both passive and interactive devices, however, is the large quantity of data that can be collected, and the needs for processing to handle such data quantities. A further issue explored is that of the reliability of data that are to be entered by respondents in interactive devices, and special concerns that may arise in processing data collected in real time, in order to be able to make use of the data for prompting or interrogating respondents. The fourth section of the paper discusses the differences between data from mobile devices and data collected in conventional self-report surveys. These differences are discussed in relation to the user of the data and explore some of the potentials that may exist for changes in modelling results from using such data. A further issue that is explored in this section is that of imputed data from mobile technology devices, as compared to imputation in conventional travel surveys. The paper concludes by drawing conclusions about the usefulness of mobile technologies to collect and process data, outlining the requirements that such data collection may present to the analyst, the limitations of such data collection, and the advantages that it brings compared to conventional methods. The paper speculates as to what the possible future might look like in terms of the extent to which such mobile technologies may be used either to supplement or replace conventional methods of data collection. The paper also draws conclusions on how ready the technology is today and what advances one may expect in the short and medium term from this form of technology. Limitations on the technology are also discussed.