1,721,018 research outputs found
Evidence, probability and relative plausibility
No full textA comparison is made between probability and relative plausibility as approaches for the interpretation of evidence. It is argued that a probabilistic approach is capable of answering the criticisms of the proponents of relative plausibility. It is also shown that a probabilistic approach can answer the problem of overlapping where there is evidence that each side claims supports its theory of what happened
The principle of total evidence reprised
Full text linkThe Principle of Total Evidence, postulated by Carnap in 1947, implies that to achieve the best assignation of a probability, all available information should be considered, subject to cost. For the evaluation of evidence, it is important that the best assignation of probability be made. The benefits of such an assignation are shown to be an increase in the expected utility of any decision made, a decrease in an expectation of an error of an inference that might be made and an increase in the expected weight of evidence for the correct hypothesis. A practical illustration is given with reference to a recent Italian case
A generalised Bayes' factor formula for evidence evaluation under activity level propositions: variations around a fibres scenario
Full text linkGeneralised Bayes' factors and associated Bayesian networks are developedfor the transfer of extrinsic evidence at the activity level, developments thatextend previous work on activity level evaluation. A strategy for the assessmentof extrinsic evidence is developed in stages with progressive increases incomplexity. The final development is illustrated with an example involvingfibres from clothing. This provides a list of factors involved in the considerationof a transfer case with activity level propositions and their roles in thedetermination of evidential valu
The meaning of justified subjectivism and its role in the reconciliation of recent disagreements over forensic probabilism
Full text linkIn this paper we reply to recent comments in this Special Issue according to which subjective probability is not considered to be a concept fit for use in forensic evaluation and expert reporting. We identify the source of these criticisms to lie in a misunderstanding of subjective probability as unconstrained subjective probability; a lack of constraint that neither corresponds to the way in which we referred to subjective probability in our previous contributions, nor to the way in which probability assignment is understood by current evaluative guidelines (e.g., of ENFSI). Specifically, we explain that we understand subjective probability as a justified assertion, i.e. a conditional assessment based on task-relevant data and information, that may be thought of as a constrained subjective probability. This leads us to emphasise again the general conclusion that there is no gap between justified (or, reasonable) subjective probability and other concepts of probability in terms of its ability to provide assessments that are soundly based on whatever relevant information available. We also note that the challenges an expert faces in reporting probabilities apply equally to all interpretations of probability, not only to subjective probability
The consequences of understanding expert probability reporting as a decision
Full text linkIn this paper we reiterate that the personalist interpretation of probability is inevitable and as least as informed as any other allegedly more ‘objective’ definition of probability. We also argue that the problem faced by forensic scientists, the reporting on imperfect personal knowledge, in terms of probabilities, can be reconstructed as a decision problem. Tackling this problem through a rigorous decision theoretic analysis provides further argument in support of the view that optimal probability reporting is in terms of single numbers, not intervals
Dismissal of the illusion of uncertainty in the assessment of a likelihood ratio
No full textThe use of the Bayes factor (BF) or likelihood ratio as a metric to assess the probative value of forensic traces is largely supported by operational standards and recommendations in different forensic disciplines. However, the progress towards more widespread consensus about foundational principles is still fragile as it raises new problems about which views differ. It is not uncommon e.g. to encounter scientists who feel the need to compute the probability distribution of a given expression of evidential value (i.e. a BF), or to place intervals or significance probabilities on such a quantity. The article here presents arguments to show that such views involve a misconception of principles and abuse of language. The conclusion of the discussion is that, in a given case at hand, forensic scientists ought to offer to a court of justice a given single value for the BF, rather than an expression based on a distribution over a range of values
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Reconciliation of subjective probabilities and frequencies in forensic science
Full text linkThere is a continuous flow of articles published in legal and scientific journals that recite outworn direct or subtle attacks on Bayesian reasoning and/or the use of the subjective or personalistic interpretation of probability. An example is the recent paper written by Kaplan et al. (2016), who, by referring to Kafadar’s review paper (2015), opined, but did not justify, that there is a ‘. . . need to reduce subjectivity in the evaluation of forensic science’ and argued that ‘. . . the view presented here supports the use of objective probabilities’ (Kaplan et al., 2016). To understand why the objection on the use of subjective probability is not persuasive and why the widely claimed objective probabilities do not exist, one must first scrutinize the historically competing interpretations of probability and their associated definitions. The basis of the defence of the use of the subjectivist interpretation of probability is the understanding of the simple points, misunderstood by critics, that subjectivity is not a synonym for arbitrariness and that the implementation of subjectivism does not neglect the use of the acquired knowledge that is often available in terms of relative frequencies. We will illustrate these points by reference to practical applications in forensic science where probabilities are often represented by relative frequencies. In this regard, our discussion clarifies the connection and the distinction between probabilities and fre- quencies. Specifically, we emphasize that probability is an expression of our personal belief, an inter- pretation not to be equated with relative frequency as a mere summary of data. Our argument reveals the inappropriateness of attempts to interpret relative frequencies as probabilities, and naturally solves common problems that derive from such attempts. Further we emphasize that, despite the fact that they can be given an explicit role in probability assignments, neither are relative frequencies a necessary condition for such assignments nor, in forensic applications that consider events for which probabilities need to be specified, need they be meaningfully conceptualized in a frequentist perspective
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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