En kvantitativ och kvalitativ analys av bortfall från resevaneundersökningar med mobilapplikation : Hur ser bortfallet ut och hur kan det åtgärdas?

Sammanfattning: Understanding peoples travel behavior is vital when planning transportation systems. Travel surveys are used to collect peoples travel data. Lately it has been harder to recruit respondents to the traditional travel surveys which has resulted in lower data quality. TravelVu is a smartphone application that collects GPS-data and for every trip the user takes the application collects information. The user can then check the trips and adjust them and at the end of the day confirm that the trips are correct. The corrected data is later used in analyzing travel behavior. All studies have a dropout rate that need to be addressed and users drop out from TravelVus travel surveys both during the recruitment period and the phase when data is collected.  The purpose of this study is to find out when the dropout happens, if it affects the representation of different demographical groups and how to prevent the results from getting biased. The goal is to find solutions to make the distribution between the different demographic groups closer to mirroring the distribution between those groups in the population. The study was executed in three parts. The first part is a study of previous travel behavior surveys and the different methods used to collect travel data and recruit respondents. The second part is a study of data collected by TravelVu in travel surveys made in Gotland, Täby, Trollhättan and Lund. In this part discrepancies between groups with different age, gender, education, and possession of driver’s license, was studied to see if some demographic group was underrepresented in TravelVus travel surveys. The third part was an interview study with people from different demographical groups. These people had to answer questions about their attitude toward travel surveys and different travel survey methods. They also had to discuss what could influence their attitude positively or negatively, and review how inclined they felt to participate based on a recruitment letter and the application, TravelVu.   The results from the second part of the research showed that some demographic groups were more represented that other. These groups were women, people between the ages of 35 and 74 years old, people with a driver’s license, and people with higher education. This biasedness in representation is already set during the recruitment phase and during the data collection period people drop out according to this trend.  A common answer in the interviews were that people thought travel surveys meant the respondent had to put in a lot of work and that it could feel unsafe being tracked by GPS-based travel surveys. Many participants pointed out that it was hard to understand the purpose of travel surveys and how it would affect them in a positive way.  Some conclusions made from this research is that the distribution between demographic groups is set during the recruitment period, that the largest dropout rate is during the recruitment period and that the recruitment letter should be adjustable to reach different people, since the research showed that some participants wanted more information than the recruitment letter offered. This could be achieved by having links in the letter for more information for those who does not feel satisfied with the information offered in the letter and by having demos of the application which makes it possible for the respondent to try out the survey method before committing. The letter should also focus more on the positive parts of participating in a travel survey.