The Open Epidemiology Journal
2008, 1 : 48-52Published online 2008 October 15. DOI: 10.2174/1874297100801010048
Publisher ID: TOEPIJ-1-48
The Variance of the Number of Effects in an Epidemiological Cohort - The Role of Dose Uncertainty
Los Alamos National Laboratory,
1619 Central Avenue, MS A117, Los Alamos, NM 87545, USA.
ABSTRACT
Two basic formulas, for the mean and variance of the number of effects in an epidemiological cohort, are derived. The formula for variance shows “extra-binomial variation” or “overdispersion” when there is correlated uncertainty of the probability of an effect. The formulas were validated by a numerical Monte Carlo study. The method of including “epistemic” uncertainty discussed by Hofer (E. Hofer, Health Physics, 2007) is generalized to include separately uncertainty from a Bayesian posterior distribution when the prior is known, and uncertainty of the prior.