Training and accreditation of interviewers to carry out physical measurements.

Physical measurements are taken on a number of cross-sectional and longitudinal studies in the UK as well as internationally. It is well established that, with appropriate training, field interviewers are able to carry out physical measurements in a home setting. However, to ensure high quality data collection, formal accreditation is becoming increasingly common on many surveys in the US and UK. This paper describes our approach to developing an interviewer accreditation process for conducting physical measurements on the most recent wave of the Millennium Cohort Study (MCS), which took place at age 11 in 2012. The approach was informed by formal training and accreditation schemes developed for other similar large-scale and longitudinal studies. Training, practice and accreditation sessions were built into the interviewer briefing programme and supplemented by additional quality control procedures in the field. In combination, these led to improved interviewer training and support for interviewers, and provided some useful lessons and implications for future practice.