Study members begin their assessment day at 8.45 a.m. and finish around 5.15 p.m. A maximum of n = 4 Study members can participate per day and they are run through nine counterbalanced assessment sessions (modules), interspersed by short breaks at morning and afternoon tea, as well as a longer break at lunchtime. We prefer face-to-face interviews because this helps avoid problems with literacy and comprehension (between 5 and 10 % of a general population sample will have at least mild difficulties). We present the assessment modules in a countered-balanced fashion to avoid order effects and to maintain participants’ interest during the 8.5-hour assessment day (e.g. a cognitively taxing assessment is followed by a physiological assessment with low cognitive demand). We hire appropriately qualified interviewers (e.g. a clinical psychologist for the mental health assessment, a dentist for the oral health assessment, and specialist nurses for the cardiovascular assessment) and provide extensive training on the research protocols. Finally, interviewers are kept blind to the Study members’ performance in other sessions. This helps reduce the potential for interview bias and inflated associations from shared method variance.
