Randomization
As part of this sub-study, we also conducted a nested trial in which patients were randomized to one of two intervention arms to test the effectiveness of using an enhanced mailed FIT envelope versus a plain mailed FIT envelope. As shown in Fig. Enhanced and plain mailed FIT envelopes used in the mailed FIT nested randomized trialWe randomly assigned patients 1:1 to receive the enhanced or plain envelope. Using a computerized random number generator, we randomly sorted the eligible patient list and assigned one-half to the plain envelope and the other to the enhanced envelope. All other intervention characteristics were the same for patients in both intervention arms of the nested trial; the only difference was the type of mailed envelope used.