Design of a study using treatment strategies with a grace period based on cloning, censoring and weighting. Another method is comparing treatment strategies that include a grace period. Each individual is duplicated and assigned to one of two treatment strategies. In this example, Clones 1a–6a follow the strategy ‘initiate ACEi within 6 months’, whereas Clones 1b–6b follow the strategy ‘do not initiate ACEi within 6 months’. Note that Copies 1a and 1b represent the same individual. Since Copy 1a is assigned to initiating within 6 months, he is censored after Month 6, as he did not initiate treatment. The censoring is likely to be informative and inverse probability weighting is required to adjust for this.