Overdispersion in allelic counts and θ -correction in forensic genetics

Abstract A statistical model for incorporating the extra variability in allelic counts due to subpopulation structures is presented. In forensic genetics, this effect is modelled by the identical-by-decent-parameter, θ . It is shown, that θ may be defined as an overdispersion parameter capturing the extra variability from subpopulation structures. This allows derivation of maximum likelihood estimates of the allele probabilities and θ together with the computation of profile log-likelihood, confidence intervals and hypothesis testing.