Every day, 1,012 panellists drawn from a pool of over 26,000 members take part in the study by wearing the Mediawatch. On average, each panellist participates twice a year for a week at a time. The starting days of the measuring weeks are staggered evenly from Tuesday to Saturday (for logistical reasons it is not possible to start on Sunday and Monday). Over the course of a year, the panellists accumulate some 400,000 days' worth of data.