MS-SMART study: systematic sampling bias concerns – Authors' reply. Issue 6 (June 2020) - Chataway, Jeremy; De Angelis, Floriana; Connick, Peter; Parker, Richard A; Doshi, Anisha; John, Nevin; Barkhof, Frederik; Sharrack, Basil; Weir, Christopher J; Chandran, Siddharthan; ,