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General Approach to Power Calculation for Relationship Testing

NCJ Number
Forensic Science International: Genetics Volume: 9 Dated: March 2014 Pages: 186-190
Thore Egeland; Nadia Pinto; Magnus Dehli Vigeland
Date Published
March 2014
5 pages
This paper presents a standard way of measuring the ability of a battery of tests to resolve claimed family relationships.
The authors' approach is to calculate exclusion probabilities on a computer with user friendly software. The software enables the calculation of the power of exclusion (PE), which is the probability that the genotypes will be incompatible with the claimed relationship. If exclusion is impossible, the software computes the distribution of the likelihood ratio (LR). The software is part of the "R" package "paramlink," which was originally designed by Magnus Dehli Vigeland, one of this paper's authors, for pedigree manipulations and likelihood computations. The software automatically produces informative pedigree plots and calculates PE values directly. "Paramlink" provides various functions for LR pedigree analysis, including parametric LOD scores, power analysis for linkage, genotype probability distributions, and many utility functions for plotting and manipulating pedigrees and markers. LRs are calculated using the Elston-Stewart algorithm, which works well with pedigrees of any size if the number of linked markers is small. The calculations have been validated by comparison with other software whenever possible, checking against exact formulas and by simulation. Three examples are presented. The first two address the power of exclusion, illustrating and validating the general approach and implementation. The third example presents LRs. 2 tables, 4 figures, and 14 references