Figure 1

Model of empirical induction periods. The date of diagnosis for the i^th case is d _i . τ _i is the temporal lag between initiation of the disease (e.g. appearance of the first cancer cells) and diagnosis. ω _i is the induction period when causative exposures occurred. ω _ij is that time interval when the induction windows for cases i and j, ω _i and ω _j , overlapped.