General Online Research conference

Pre-recorded conference presentation: “quality of measurements from smartphone travel-app study”

Smartphone apps are starting to be commonly used to measure travel behaviour. The advantage of smartphone apps is that they can use location sensors in mobile phones to keep track of where people go at what time at relatively high precision. In this presentation, we report on a large fieldwork test conducted by Statistics Netherlands and Utrecht University in November 2018. A random sample of about 1900 individuals was drawn from the Dutch population register and invited to install an app and keep that for a week. Based on an algorithm the app divided each day into “stops” and “tracks” (trips), which were fed back to respondents in a diary-style list separately for every day. Respondents were then asked to provide further details on for example the mode of travel and purpose of trips

Having both sensor data and survey data allows us to investigate measurement error in stops, trips and details about these in some detail. This presentation focuses in identifying

1. False positives: a stop was presented to a respondent that wasn’t a stop (and by definition also a track connecting this stop to another one). How can we identify such occasions, how did respondents react to false positives, and how can we correct for this in estimates of travel behaviour?
2. False negatives: stops were missing from the diary (often because a Respondent forgot the phone, or GPS tracking was not working properly). How often did this happen, how did respondents react (they could add a stop, but often didn’t) and can we say anything about their possible impact on estimates? We conclude with a discussion of how to generally move forward in combining sensor and survey data for tracking studies.