Pevid2 {forensim} | R Documentation |
Calculates the probability of observing a set of DNA profiles conditional on a given hypothesis specifying who were the contributors to the observed profiles. All the individuals involved in the analyzed case are assumed to come from the same subpopulation with a given coancestry coefficient.
Pevid2(stain, freq, x, T = NULL, V = NULL, theta = 0)
stain |
vector of distinct alleles (from one specific locus) found in the crime sample. |
freq |
vector of the corresponding allele frequencies in the global population |
x |
the number of unknown contributors to the mixture |
T |
object of class genotype (package genetics), or a vector of strings where each string contains two alleles separated by '/', corresponding to one known contributor. The length of the vector equals the number of known contributors. Default is NULL. |
V |
object of class genotype (package genetics), or a vector of strings where each string contains two alleles separated by '/', corresponding to one known non-contributor. The length of the vector equals the number of known non-contributors. Default is NULL. |
theta |
a float in [0,1[. theta is equivalent to Wright's Fst. In case of
population
subdivision, it allows a correction of the allele frequencies in the subpopulation of
interest |
Please note that the Pevid2
function is an improved version of the Pevid.gen
function from the forensic package by Miriam Marusiakova (which explains the 2 in the function
name). Pevid2
calls external functions in C code.
Hinda Haned haned@biomserv.univ-lyon1.fr
Curran JM, Triggs CM, Buckleton J, Weir BS. Interpreting DNA Mixtures in Structured Populations. J Forensic Sci 1999;44(5): 987-995
# A rape case in Hong Kong (Hu and Fung, Int J Legal Med 2003) # The stain shows alleles 14, 15, 17 and 18 at locus D3S1358. stain=c(14,15,17,18) # suspect's profile: "14/17" suspect<-"14/17" # victim's profile: "15/18" victim<-"15/18" # corresponding allele frequencies freq<-c(0.033,0.331,0.239,0.056) # Prosecution proposition: Contributors were the victim and the suspect # defence proposition: Contributors were the victim and 1 unknown contributor # from the same subpopulationas the victim # Evaluation of the defence proposition, in case of independence between alleles Pevid2(stain, freq, x=1, T = victim) # note that if theta=0, the suspect's profile plays no role in the calculation #and the same result is obtained Pevid2(stain, freq, x=1, T = victim, V = suspect) # In case of allele dependencies, measured by theta=0.03 Pevid2(stain, freq, x=1, T = victim, V = suspect, theta = 0.03)