Quality assessment of location data obtained by the GPS-enabled PARROTS survey tool

A custom tool, PARROTS (PDA system for Activity Registration and Recording of Travel Scheduling) was developed to collect activity-travel diary data and global positioning system (GPS) based location data during trips. This tool is currently deployed in a survey that is carried out on 2500 households in Flanders (Belgium). To judge the effect of the PARROTS tool on the quality of activity-travel diaries, a paper-and-pencil diary was designed and deployed as well. This article discusses the impact on travel and location data quality of a GPS-enabled personal digital assistant (PDA) data collection tool featuring consistency checks. This impact includes both activity-travel diary data quality and GPS data quality. The quality of the GPS-based location data collection is assessed in terms of both quantity and quality of the obtained GPS logs. The location data quality is obtained using the fraction of GPS logs containing actual location information. Based on the GPS logger activity, a usage profile was obtained and compared to the location data resulting from the survey. Based on the analyses presented above, it is concluded that PARROTS provides both high quality activity-travel diary data and GPS-based location information, while keeping the burden for the respondents at an acceptable level.