NCJ Number
236873
Journal
Journal of Forensic Sciences Volume: 56 Issue: 6 Dated: November 2011 Pages: 1448-1456
Date Published
November 2010
Length
9 pages
Annotation
The current familial searching strategies are generally based on either Identity-By-State (IBS) (i.e., number of shared alleles) or likelihood ratio (i.e., kinship index [KI]) assessments. In this study, the expected IBS match probabilities given relationships and the logic of the likelihood ratio method were addressed.
Abstract
Further, the false-positive and false-negative rates of the strategies were compared analytically or by simulations using Caucasian population data of the 13 CODIS Short Tandem Repeat (STR). IBS greater than or equal to 15, IBS greater than or equal to 16, KI greater than or equal to 1000, or KI greater than or equal to 10,000 were found to be good thresholds for balancing false-positive and false-negative rates. IBS greater than or equal to 17 and/or KI greater than or equal to 1,000,000 can exclude the majority of candidate profiles in the database, either related or not, and may be an initial screening option if a small candidate list is desired. Polices combining both IBS and KI can provide higher accuracy. Typing additional STRs can provide better searching performance, and lineage markers can be extremely useful for reducing false rates. (Published Abstract)