forensim (version 2.0)

LR2: Likelihood ratio for DNA evidence interpretation (2): a sophistacted version of function LR()

Description

LR2 Allows the calculation of likelihood ratios for a piece of DNA evidence, for any number of replicates, any number of contributors, and when drop-in and drop-out are possible.

Usage

LR2(Repliste, Tp, Td, Vp, Vd, xp, xd, theta, prDHet, prDHom, prC, freq)

Arguments

Repliste

list of the alleles present at a given locus for any number of replicates. If there are two replicates, showing alleles 12,13, and 14 respectively, then Repliste should be given as list(c(12,13),14).

Tp

vector of genotypes for the known contributors under a Hp. Should be given in the genetics format, i.e., genotype 1217 should be given as '12/17' (character), and genotypes 1217,1416, should be given as a vector: c('12/17','14/16').

Td

vector of genotypes for the known contributors under a Hd. Should be in the same format as Tp. If there are no known contributors under Hd, then set Td to NULL.

Vp

vector of genotypes for the known non-contributors (see References section) under a Hp. Should be given in the genetics format, i.e., genotype 1217 should be given as '12/17' (character), and genotypes 1217,1416, should be given as a vector: c('12/17','14

Vd

vector of genotypes for the known non-contributors (see References section) under a Hd. Should be in the same format than Vp, if empty, set to NULL.

xp

Number of unknown individuals under Hd. Set to 0 if there are no unknown contributors.

xd

Number of unknown individuals under Hd. Set to 0 if there are no unknown contributors.

theta

thete correction, value must be taken in [0,1)

prDHet

probability of dropout for heterozygotes. It is possible to assign different values per contributor. In this case, prDHet must be a vector, of length the number of contributors in T + x, and the probabilities must be given in this order. if t

prDHom

probability of dropout for homozygotes. See description ofr argument PrDHom.

prC

probability of drop-in

freq

vector of the corresponding allele frequencies of the analysed locus in the target population

References

Gill, P.; Kirkham, A. & Curran, J. LoComatioN: A software tool for the analysis of low copy number DNA profiles Forensic Science International, 2007, 166(2-3), 128-138 Curran, J. M.; Gill, P. & Bill, M. R. Interpretation of repeat measurement DNA evidence allowing for multiple contributors and population substructure Forensic Science International, 2005, 148, 47-53

See Also

LRmixTK

Examples

#load allele frequencies
library(forensim)
data(ngm)
#create vector of allele frequencies
d10<-ngm$tab$D10
#single  dropout parameter for all contributors
LR2(list(12,13,14),Tp='12/13',Td=NULL,Vp=NULL,Vd=NULL,xd=2,xp=1,theta=0,prDHet=0.2,prDHom=0.1,prC=0,freq=d10)

#different dropout probabilities for contributor 1 in T and the unknown contributor: 0.2 for the first one (heterozygote, corresponding value is 0 in the homozygote vector), 0.7 for the second one if it is a heterozygote and 0.3 if its is a homozygote.

LR2(list(12,13,14),Tp='12/13',Td=NULL,Vp=NULL,Vd=NULL,xd=2,xp=1,theta=0,prDHet=c(0.2,0.70),prDHom=c(0,0.3),prC=0,freq=d10)