The evidential value in the DNA database search controversy and the two-stain problem.
Does the evidential strength of a DNA match depend on whether the suspect was identified through database search or through other evidence ("probable cause")? In Balding and Donnelly (1995, Journal of the Royal Statistical Society, Series A 158, 21-53) and elsewhere, it has been argued that the evidential strength is slightly larger in a database search case than in a probable cause case, while Stockmarr (1999, Biometrics 55, 671-677) reached the opposite conclusion. Both these approaches use likelihood ratios. By making an excursion to a similar problem, the two-stain problem, we argue in this article that there are certain fundamental difficulties with the use of a likelihood ratio, which can be avoided by concentrating on the posterior odds. This approach helps resolving the above-mentioned conflict.
Divisie Wiskunde, Faculteit der Exacte Wetenschappen, Vrije Universiteit, De Boelelaan 1081a, 1081 HV Amsterdam, The Netherlands. rmeester@cs.vu.nl
Ronald
R
Meester
Marjan
M
Sjerps
D001699:Biometry; D001801:Blood Stains; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D030561:Databases, Nucleic Acid; D005554:Forensic Medicine / Q000706:statistics & numerical data*; D006801:Humans; D016013:Likelihood Functions; D008957:Models, Genetic; D015233:Models, Statistical; D016017:Odds Ratio; D013194:Staining and Labeling
D004247:DNA