Figure 3From: A procedure to characterize geographic distributions of rare disorders in cohortsSensitivity and specificity for a simulated rectangular cluster using an elliptical scan. One hundred simulations of a rectangular cluster with aspect ratio varying from 2 to 10, relative risk = 2, background prevalence = 0.004 and nmax= 1,000. The higher aspect ratios create narrow elongated clusters that are harder to capture giving the tests lower sensitivity and having less effect on specificity.Back to article page