Source: Example from Rothman, K. J. 1986. Modern Epidemiology. Boston: Little, Brown. Rothman used data from Rothman, K. J., and R. R. Monson. 1973. Survival in trigeminal neuralgia. Journal of Chronic Diseases 26: 303-309. https://doi.org/10.1016/0021-9681(73)90033-7.