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J S Buckleton

Publications and source records attributed to J S Buckleton.

At least 19 recordsLinked to original sources
PubMed2006

DNA commission of the International Society of Forensic Genetics: Recommendations on the interpretation of mixtures.

The DNA commission of the International Society of Forensic Genetics (ISFG) was convened at the 21st congress of the International Society for Forensic Genetics held between 13 and 17 September in the Azores, Portugal. The purpose of the group was to agree on guidelines to encourage best practice that can be universally applied to assist with mixture interpretation. In addition the commission was tasked to provide guidance on low copy number (LCN) reporting. Our discussions have highlighted a significant need for continuing education and research into this area. We have attempted to present a consensus from experts but to be practical we do not claim to have conveyed a clear vision in every respect in this difficult subject. For this reason, we propose to allow a period of time for feedback and reflection by the scientific community. Then the DNA commission will meet again to consider further recommendations.

Alleles↗
PubMed2005

A study of the performance and utility of annealing in forensic glass analysis.

The use of annealing in forensic glass casework is reviewed. New data is presented that suggests a continuous approach to the interpretation of such data may be superior to the classification approach. Data are presented supporting the previously observed relationship between change in refractive index (RI) and the thickness of the glass pane. An examination of the possible assumption of independence between RI and change in RI is undertaken.

Journal Article↗
PubMed2003

Effects of population structure and admixture on exact tests for association between Loci.

The probability of multilocus genotype counts conditional on allelic counts and on allelic independence provides a test statistic for independence within and between loci. As the number of loci increases and each sampled genotype becomes unique, the conditional probability becomes a function of total heterozygosity. In that case, it does not address between-locus dependence directly but only indirectly through detection of the Wahlund effect. Moreover, the test will reject the hypothesis of allelic independence only for small values of heterozygosity. Low heterozygosity is expected for population subdivision but not for population admixture. The test may therefore be inappropriate for admixed populations. If individuals with parents in two different populations are always considered to belong to one of the populations, then heterozygosity is increased in that population and the exact test should not be used for sparse data sets from that population. If such a case is suspected, then alternative testing strategies are suggested.

Data Interpretation, Statistical↗
PubMed2001

How many samples from a drug seizure need to be analyzed?

Recently Aitken introduced an outstanding advance in the approach to decision making regarding drugs sampling. Unfortunately this approach has not, as yet, been widely implemented despite being based on a solid mathematical foundation. In this paper we advocate a Bayesian approach along the lines of that outlined by Aitken but designed to be both easily understood with less mathematical sophistication and implementable using standard EXCEL software. The emphasis is placed on encouraging the application of this methodology to routine case work by explaining the statistics involved. Minor differences exist between this approach and that of Aitken in both the modeling of the prior probability and in dealing with the discrete nature of the samples. These differences in no way detract from the sound mathematical foundation of the approach.

Journal Article↗
PubMed1996

Statistical analysis of a large file of data from STR profiles of British Caucasians to support forensic casework.

Data from nearly 2500 British Caucasians, profiled using an STR quadruplex, have been analysed. The data came from several laboratories and represent samples from different geographical distributions. Analysis of the combined files shows that previous reports of failed independence tests were the results of sampling effects. A further convincing proof is given of the robustness of the statistical methods used to estimate evidential value in casework. Comparisons between different samples show that regional effects between Scotland and the South of England have no importance from the forensic viewpoint.

Adult↗
PubMed1989

Methyl 2-[4-(2-chloroethyl)-2,3-dihydro-7-nitroquinoxalin-1-yl]benzoate from intramolecular cyclization of a nitroaromatic mustard.

C18H18CIN3O4, Mr = 375.81, orthorhombic, P212121, a = 11.000 (3), b = 8.023 (2), c = 19.316 (5) A, V = 1704.68 A3, Z = 4, Dm = 1.46 (1), Dx = 1.417 g cm-3, Mo Kalpha, lambda = 0.71069 A, mu = 1.82 cm-1, F(000) = 760, T = 293 (1) K, R = 0.051 for 985 [I greater than 2.5 sigma(I)] reflections. X-ray analysis confirms that the nitroaromatic mustard methyl N-(2-[bis(2-chloroethyl)amino]- 5-nitrophenyl)anthranilate undergoes rapid intramolecular cyclization, but the product is the 7-nitro rather than the 6-nitro derivative previously reported [Chambers & Denny (1986).

Antineoplastic Agents↗
PubMedDate not supplied

Paternity calculations from DNA multilocus profiles.

DNA profiles prepared using multilocus probes can provide valuable evidence in cases of disputed parentage. This paper describes a simple approach to the analysis of the profiles from a mother, child and putative father in a case of disputed paternity. Although the treatment has not yet been extended to deal with cases in which mutant bands may have appeared, it has already proved useful in casework. The analysis is illustrated by a numerical example calculated on a computer spreadsheet.

Bayes Theorem↗
PubMedDate not supplied

Calculating the frequency of occurrence of a blood type for a 'random man'.

A scheme is offered for the calculation of blood group frequencies for mixed racial populations. The issue of which population to model is discussed. Consideration is also given to the racial composition of the desired survey and to the rule of mutual independence. The scheme can in many cases be applied to existing data.

Bayes Theorem↗
PubMedDate not supplied

Glass on clothing and shoes of members of the general population and people suspected of breaking crimes.

The outer clothing and footwear of 122 people attending a university gymnasium and a private gymnasium were searched for fragments of glass. Both the surfaces and the pockets of the clothing and the uppers and soles of the footwear were searched. New Zealand forensic glass cases have been reviewed to determine the amount of non-matching glass present on the clothing of people who are suspected of breaking crimes. Data from 114 suspects who had no matching glass on their clothing and shoes were accumulated. Statistical modelling techniques have been applied to the data collected.

Journal Article↗
PubMedDate not supplied

The fallacy of independence testing and the use of the product rule.

Use of the product rule which implies the assumption of within and between locus independence, is still common, particularly in the United States of America. Whilst it may be considered by some to be an acceptable approximation it is not logical to suggest that independence testing somehow "validates" its use. This paper discusses the nature of this fallacy.

DNA Fingerprinting↗
PubMedDate not supplied

Assessing uncertainty in DNA evidence caused by sampling effects.

Sampling error estimation in forensic DNA testimony was discussed. Is an estimate necessary and how should it be made? The authors find that all modern methods have areas of strength and weakness. The assessment of which is the 'best' is subjective and depends on the performance of the method, the type of problem (criminal work or paternity), the database size and availability of computing software and support. The authors preferred the highest posterior density approach for performance, however the other methods all have areas where their performance is adequate. For single-contributor stains normal approximation methods are suitable, also the bootstrap and the highest posterior density method. For multiple-contributor stains or other complex situations the match probability expressions become quite complex and it may not be possible to derive the necessary variance expressions. The highest posterior density or the bootstrap provide a better general method, with non-zero theta. The size-bias correction and the factor of 10 approaches may be considered acceptable by many forensic scientists as long as their limitations are understood.

DNA↗
PubMedDate not supplied

The two trace transfer problem re-examined.

The classical two trace transfer problem initially discussed by Evett is reconsidered [Evett IW. On Meaningful Questions: A Two-Trace Transfer Problem. Journal of the Forensic Science Society 1987; 27: 375-381]. In this problem we consider the situation where there are two stains of differing types at a crime scene. Evett considered the situation where both are known to be relevant to the offence. It was further assumed that there were exactly two offenders. Reanalysis of this problem suggests that the key consideration is the conditioning on there being exactly two offenders, not that there were two stains. The treatment here leads easily to a generalisation in which stains have differing relevance and there are k offenders.

Crime↗