Burton CD, et al. - This paper aimed at distinguishing the variation in referral threshold and variation in accurate selection of patients for referral in fast-track referrals for possible cancer. It also inspected the factors related to threshold and accuracy and focused on modeling the effects of changing thresholds. It was discovered that this new method allowed a more precise elucidation of the variation in referral and quality improvement activities to be targeted. Modest effects could be gained on detection rates and a large increase in demand for diagnostic services via a change in the referral thresholds without increasing accuracy.