Highlights
- •We demonstrate examples where the likelihood ratio may be easily obtained to help with the internal validation of probabilistic software.
- •We do this by way of example using three software packages: STRmix™, LRmix, and Lab Retriever.
- •We provide profiles and equations so the calculations may be replicated or applied to different software.
Abstract
There has been a recent push from many jurisdictions for the standardisation of forensic
DNA interpretation methods. Current research is moving from threshold-based interpretation
strategies towards continuous interpretation strategies. However laboratory uptake
of software employing probabilistic models is slow. Some of this reluctance could
be due to the perceived intimidating calculations to replicate the software answers
and the lack of formal internal validation requirements for interpretation software.
In this paper we describe a set of experiments which may be used to internally validate
in part probabilistic interpretation software. These experiments included both single
source and mixed profiles calculated with and without dropout and drop-in and studies
to determine the reproducibility of the software with replicate analyses. We do this
by way of example using three software packages: STRmix™, LRmix, and Lab Retriever.
We outline and demonstrate the profile examples where the expected answer may be calculated
and provide all calculations.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Forensic Science International: GeneticsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- The Connti-Vecchiotti Report.2011 (Available from: http://knoxdnareport.wordpress.com/, (cited 5 May 2014))
- Issues in gathering, interpreting and delivering DNA evidence.in: Expert Evidence Conference, Canberra2011
- Fallible DNA evidence can mean prison or freedom.New Sci. 2010; 207: 8-11
- NIST Mixture Interpretation Interlaboratory Study 2005 (MIX05).in: Promega's Sixteenth International Symposium on Human Identification, Grapevine, TX2005
- SWGDAM Interpretation Guidelines for Autosomal STR Typing by Forensic DNA Testing Laboratories.2010 (Available from: http://www.fbi.gov/hq/lab/html/codis_swgdam.pdf)
- Interpretation of DNA mixtures – European consensus on principles.Forensic Sci. Int. Genet. 2007; 1: 291-292
- DNA commission of the International Society of Forensic Genetics: recommendations on the interpretation of mixtures.Forensic Sci. Int. 2006; 160: 90-101
- DNA commission of the International Society of Forensic Genetics: recommendations on forensic analysis using Y-chromosome STRs.Int. J. Legal Med. 2001; 114: 305-309
- DNA commission of the International Society of Forensic Genetics: recommendations on the evaluation of STR typing results that may include drop-out and/or drop-in using probabilistic methods.Forensic Sci. Int. Genet. 2012; 6: 679-688
- Focus issue – analysis and biostatistical interpretation of complex and low template DNA samples.Forensic Sci. Int. Genet. 2012; 6: 677-678
- The interpretation of single source and mixed DNA profiles.Forensic Sci. Int. Genet. 2013; 7: 516-528
- Validating TrueAllele® DNA mixture interpretation.J. Forensic Sci. 2011; 56: 1430-1447
- Interpreting low template DNA profiles.Forensic Sci. Int. Genet. 2009; 4: 1-10
- A new methodological framework to interpret complex DNA profiles using likelihood ratios.Forensic Sci. Int. Genet. 2013; 7: 251-263
- A comparison of statistical models for the analysis of complex forensic DNA profiles.Sci. Justice. 2014; 54: 66-70
- Statistical evaluation of forensic DNA profile evidence.Annu. Rev. Stat. Appl. 2014; 1: 20.1-20.24
- Quality Assurance Standards for Forensic DNA Testing Laboratories.2011, September 1 (Available from: http://www.fbi.gov/about-us/lab/codis/qas-standards-for-forensic-dna-testing-laboratories-effective-9-1-2011, (cited 30 March 2014))
- Validation Guidelines for DNA Analysis Methods.2012 (Available from: http://swgdam.org/SWGDAM_Validation_Guidelines_APPROVED_Dec_2012.pdf, (cited 30 March 2014))
- Forensim an open-source initiative for the evaluation of statistical methods in forensic genetics.Forensic Sci. Int. Genet. 2011; 5: 265-268
- Calculating the weight of evidence in low-template forensic DNA casework.J. Forensic Sci. 2013; 58: 234-259
- A graphical simulation model of the entire DNA process associated with the analysis of short tandem repeat loci.Nucl. Acids Res. 2005; 33: 632-643
- Degradation of forensic DNA profiles.Aust. J. Forensic Sci. 2013; 45: 445-449
- Characterising stutter in forensic STR multiplexes.Forensic Sci. Int. Genet. 2012; 6: 58-63
- Developing allelic and stutter peak height models for a continuous method of DNA interpretation.Forensic Sci. Int. Genet. 2013; 7: 296-304
- DNA profile match probability calculation: how to allow for population stratification, relatedness, database selection and single bands.Forensic Sci. Int. 1994; 64: 125-140
- National Research Council Committee on, DNA. Forensic Science, The Evaluation of Forensic, DNA Evidence.National Academy Press, Washington, DC1996
- LoComatioN: a software tool for the analysis of low copy number DNA profiles.Forensic Sci. Int. 2007; 166: 128-138
- National recommendations of the technical UK DNA working group on mixture interpretation for the NDNAD and for court going purposes.Forensic Sci. Int. Genet. 2008; 2: 76-82
- A universal strategy to interpret DNA profiles that does not require a definition of low-copy-number.Forensic Sci. Int. Genet. 2010; 4: 221-227
- AmpFlSTR Identifiler Amplification Kit User Guide.Foster City, CA, Applied Biosystems2009
- Population data on the thirteen CODIS core short tandem repeat loci in African Americans, US, Caucasians, Hispanics, Bahamanians, Jamaicans and Trinidadians.J. Forensic Sci. 1999; 44: 1277-1286
- Population data on the STR Loci D2S1338 and D19S433.Forensic Sci. Commun. 2001; 3 (Available at http://www.fbi.gov/about-us/lab/forensic-science-communications/fsc/july2001/index.htm/budowle2.htm)
- Genotype profiles for six population groups at the 13 CODIS short tandem repeat core loci and other PCR-based loci.1999 (Available from: http://www.fbi.gov/programs/lab/fsc/backissu/july1999, (cited July 1999))
- Estimating the probability of allelic drop-out of STR alleles in forensic genetics.Forensic Sci. Int. Genet. 2009; 3: 222-226
- Utilising allelic dropout probabilities estimated by logistic regression in casework.Forensic Sci. Int. Genet. 2014; 9: 9-11
- Likelihood ratio statistics for DNA mixtures allowing for drop-out and drop-in.Forensic Sci. Int. Genet. Suppl. Series. 2011; 3: e240-e241
- The two trace transfer problem revisited.Sci. Justice. 2003; 43: 127-134
- Relaxation of the assumption of relevance and an application to one-trace and two-trace problems.J. Forensic Sci. Soc. 1994; 34: 17-21
- Bayesian networks and the value of the evidence for the forensic two-trace transfer problem.J. Forensic Sci. 2012; 57: 1199-1216
- Modeling the forensic two-trace problem with Bayesian networks.Artif. Intell. Law. 2013; 21: 221-252
- On meaningful questions: a two-trace transfer problem.J. Forensic Sci. Soc. 1987; 27: 375-381
- The evidential value in the DNA database search controversy and the two-stain problem.Biometrics. 2003; 59: 727-732
- Euroforgen-NoE collaborative exercise on LRmix to demonstrate standardization of the interpretation of complex DNA profiles.Forensic Sci. Int. Genet. 2014; 9: 47-54
- Using continuous DNA interpretation methods to revisit likelihood ratio behaviour.Forensic Sci. Int. Genet. 2014; 11: 144-153
- An illustration of the effect of various sources of uncertainty on DNA likelihood ratio calculations.Forensic Sci. Int. Genet. 2014; 11: 56-63
- Searching mixed DNA profiles directly against profile databases.Forensic Sci. Int. Genet. 2014; 9: 102-110
Article info
Publication history
Published online: October 03, 2014
Accepted:
September 23,
2014
Received in revised form:
September 10,
2014
Received:
May 25,
2014
Identification
Copyright
© 2014 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
