Total nonresponse adjustment of the Ile-de-France 2023 Global Travel Survey

The Île-de-France Global Travel Survey (EGT) 2023 is a large-scale study aimed at measuring the travel behaviors of residents in the region. Like all surveys, EGT is susceptible to nonresponse bias, which arises when certain population groups are underrepresented due to their failure to respond. Addressing this bias is essential to ensuring the reliability of survey findings. This paper explores weighting and nonresponse correction techniques applied to EGT 2023. A key focus is on response mechanisms, modeled using logit regression for CAPI (Computer-Assisted Personal Interviewing) and CATI (Computer-Assisted Telephone Interviewing) surveys. The weighting strategy involves a two-step process: first, modeling the nonresponse mechanism to adjust for biases, and second, performing calibration on margins using data from FIDELI (Demographic File of Tax Origin on Housing and Individuals) and the population census. The study highlights key socio-demographic factors affecting response rates, including income, household structure, geographic location, and age, and discusses the differences in response behaviors between CAPI and CATI survey modes. It contributes to the broader discussion on survey methodologies by demonstrating how carefully designed weighting procedures can enhance data reliability in transport studies.