We mainly use face-to-face interviewing to collect data from cohort members. We do this to help maximise response rates, and because some of our studies involve physical measurements, biological samples and direct assessments of cognitive function. We have also used telephone interviewing, and the web, to collect data, sometimes in combination with each other and with face-to-face interviewing.
Web data collection is a particular focus for us. We have used this mode in major sweeps of the National Child Development Study (NCDS), Next Steps and the Millennium Cohort Study (MCS), and we are considering whether to make greater use of the web in our studies, including between major sweeps.
Our research interests are around the implications of mode choice in longitudinal surveys, In particular, we focus on how to make the most effective use of the web, whilst ensuring both data quality and high-participation rates and understanding the impact of mode on measurement.