Fig. 4From: Designs for adding a treatment arm to an ongoing clinical trialExample of adding a single experimental treatment arm to a two-arm trial comparing treatment 1 to control. The first dashed vertical line represents when the new treatment arm (treatment 2) is added to the trial. The second dashed vertical line represents when treatment 1 finishes recruiting and the third dashed vertical line represents when treatment 2 and control finish recruiting. The allocation ratios are adapted when treatment 2 is added to the trial and again when treatment 1 finishes recruiting. The allocation ratios and sample sizes in each stage for each treatment are displayedBack to article page