Randomization, Allocation Concealment, and Blinding

The allocation schedule was computer-generated by the study biostatistician (ZB) using simple unrestricted randomization. The allocation sequence was applied to a de-identified list of eligible physicians (May 2017) exported from Cancer Care Ontario. Because Cancer Care Ontario could distribute only one type of e-mail message at a time, the order in which the 8 message types were sent was determined randomly every month. The e-mail message versions were sent at 45-minute intervals starting at 09h00 on the 10th day of each month (or if that day fell on a weekend, on the next business day) between 10 May and 10 September 2017.

Randomization was conducted using the SAS software application (version 9.4: SAS Institute, Cary, NC, U.S.A.).