De Finetti's subjectivism, the assessment of probabilities and the evaluation of evidence: a commentary for forensic scientists.

This paper presents the historical and philosophical definition of subjective probabilities (also called degree of belief or Bayesian probabilities). It presents a case for the scientist to use subjective probabilities in the process of parameter estimation and evidence evaluation under the Bayesian framework. It is emphasised that Bayesian methodology does not pretend to get the 'true' probabilities: it is an effective method to analyse, criticise, check the 'coherence' of people's opinions, and to help them in revising their opinions in a 'coherent' way

Modeling the forensic two-trace problem with Bayesian networks

The forensic two-trace problem is a perplexing inference problem introduced by Evett (J Forensic Sci Soc 27:375-381, 1987). Different possible ways of wording the competing pair of propositions (i.e., one proposition advanced by the prosecution and one proposition advanced by the defence) led to different quantifications of the value of the evidence (Meester and Sjerps in Biometrics 59:727-732, 2003). Here, we re-examine this scenario with the aim of clarifying the interrelationships that exist between the different solutions, and in this way, produce a global vision of the problem. We propose to investigate the different expressions for evaluating the value of the evidence by using a graphical approach, i.e. Bayesian networks, to model the rationale behind each of the proposed solutions and the assumptions made on the unknown parameters in this problem

Value of DNA tests: a decision perspective

Before a Court of Law testifying in DNA-evidence cases, scientists are often challenged with the idea that the more markers (loci) the better, i.e., why does the scientist not use 16 or more markers? This paper introduces a new perspective, decision analysis, to deal with the problem of the number of markers to type in a criminal context. The decision-making process, which plays a key role in the routine work of a forensic scientist, consists of the rational choice, given personal objectives, between two or more possible outcomes when the consequences of the choice are uncertain. Simulated results support the hypothesis that analytical added value does not increase with the number of markers

Knowledge Reuse Mechanisms for Categorizing Related Image Sets

. This chapter introduces the concept of classier knowledge reuse as a means of exploiting domain knowledge taken from old, previously created, relevant classiers to assist in a new classication task. Knowledge reuse helps in constructing better generalizing classiers given few training examples and for evaluating images for search in an image database. In particular, we discuss a knowledge reuse framework in which a supra-classier improves the performance of the target classi er using information from existing support classiers. Soft computing methods can be used for all three types of classiers involved. We explore supra-classier design issues and introduce several types of supra-classiers, comparing their relative strengths and weaknesses. Empirical examples on real world image data sets are used to demonstrate the eectiveness of the supra-classier framework for classi- cation and retrieval/search in image databases. Keywords: knowledge reuse, image classication, image database, curse of dimensionality, soft classiers

Forensic identification of urine samples: a comparison between nuclear and mitochondrial DNA markers.

Urine samples from 20 male volunteers of European Caucasian origin were stored at 4 degrees C over a 4-month period in order to compare the identification potential of nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) markers. The amount of nDNA recovered from urines dramatically declined over time. Consequently, nDNA likelihood ratios (LRs) greater than 1,000 were obtained for 100, 70 and 55% of the urines analysed after 6, 60 and 120 days, respectively. For the mtDNA, HVI and HVII sequences were obtained for all samples tested, whatever the period considered. Nevertheless, the highest mtDNA LR of 435 was relatively low compared to its nDNA equivalent. Indeed, LRs obtained with only three nDNA loci could easily exceed this value and are quite easier to obtain. Overall, the joint use of nDNA and mtDNA markers enabled the 20 urine samples to be identified, even after the 4-month period