Figure 1

Individual examples of person-year contributions to screening exposure and non-exposure under a variety of screening participation scenarios. The total cumulated person-years of participation and non-participation in screening up to the end of 2003 (vertical line) in a hypothetical cohort of 20 women aged 40–65 years in 1999. Cumulated person-years contributing to participation is 18, and the total cumulated person-years from first eligibility contributing to screening non-participation is 30.