The Error in “Error Rate”: Why Error Rates Are So Needed,Yet So Elusive

Establishing error rates is crucial for knowing how well one is performing, determining whether improvement is needed, measuring whether interventions are effective, as well as for providing transparency. However, the flurry of activities in establishing error rates for the forensic sciences has largely overlooked some fundamental issues that make error rates a problematic construct and limit the ability to obtain a meaningful error rate. These include knowing the ground truth, establishing appropriate databases, determining what counts as an error, characterizing what is an acceptable error rate, ecological validity, and transparency within the adversarial legal system. Without addressing these practical and theoretical challenges, the very notion of a meaningful error rate is limited.     

Composite Machine Learning Algorithm for Material Sourcing,

This study developed a composite machine learning algorithm for attribution of materials of forensic interest (like ammonium nitrate) to original sources. k-nearest neighbor and random forest models were used for source elimination and classification, respectively, in a two-step, composite algorithm based on particle color, size/shape, and trace element concentration features. Novel approaches for simulation to supplement within-source reference features based on empirically measured multi-lot analyses, an improved hold-one-lot-out method for cross-validation, an assessment of the likelihood of the presence of a reference sample, fusion of the source probabilities from the respective classification models, and the calculation of metrics for assessing ensemble sourcing performance are described. Excellent sourcing predictions were obtained; the sourcing algorithm identified the correct source as the top choice 89% of the time, and the correct source was identified to be an average of 2.7 times more likely than the most likely incorrect source.     

Examination of Hacking and Blunt Force Skeletal Trauma

Hacking trauma is prevalent in forensic cases involving genocide and dismemberment, but research into the identification of this type of trauma is lacking. The present study examines characteristics of hacking and blunt force skeletal trauma in order to determine if there is a point at which blunt force trauma becomes distinguishable from hacking trauma. Ten implements with a range of blade angles (i.e., the striking surface of the implement) were used in conjunction with a controlled-force hacking device to impact 100 limb bones of white-tailed deer (Odocoileus virginianus). Observations of the trauma included the occurrence and degree of fragmentation, the entrance widths of the impacts, and composite scores of six hacking characteristics, especially the distinctive V-shaped kerf. ANOVA tests and regression analyses were used to assess the relationships between these characteristics and the blade angles. A significant relationship (p-value = 0.011) was found between the composite hacking scores and the blade angles, indicating that blunt force and hacking trauma can be distinguished. The entrance widths of the impacts exhibited a significant relationship with the blade angles (p-value = 0.037). There was also a significant relationship between the visibility of a V-shaped kerf in the bones (p-value = 0.003), with visibility decreasing around the 60° blade angle. These data should assist in establishing guidelines to differentiate hacking and blunt force skeletal trauma in cases where the implement is on a spectrum between sharp and blunt.     

New Approaches to Age Estimation Using Palatal Suture Fusion

Palatal suture fusion has seen little testing and/or application due in part to an inadequately described relationship to formal age ranges. This study presents a modified scoring method that examines fusion on samples of modern documented adult males and compares two Bayesian approaches to age estimation. In the first analysis, American and Portuguese collections were used to derive univariate and multivariate transition analysis (TA) parameters, which combined with an informative prior, estimated age in a sample of modern Americans and Portuguese. For the second analysis, a Bayesian multiple linear regression (BMLR) used indicator statuses as the independent variables with age as the dependent variable. Highest posterior density regions (HPDRs) and highest posterior density intervals (HDI) were calculated for a holdout sample. Final age estimates for the methods were tested for accuracy using cumulative binomial tests at 75% and 90% coverages. The HPDRs from multivariate TA captured age better for younger individuals, but consistently underaged. The cumulative binomial tests on the BMLR results indicated the prediction intervals performed as expected, and we show they are narrower (more precise) and/or more accurate than the corresponding HPDR. The modified method presented here formally links palatal suture obliteration to age using two different approaches, one of which (BMLR) is new to the aging literature. The BMLR provided results free from bias and more reasonable age ranges while maintaining accuracy. We present a look-up table and a free, simple R file for users to download and run their own estimates with BMLR.     

Single Nucleotide Polymorphism Assay for Genetic Identification of Lophophora williamsii*

Lophophora is a member of the Cactaceae family, which contains two species: Lophophora williamsii and L. diffusa. Lophophora williamsii is an illegal plant containing mescaline, a hallucinogenic alkaloid. In this study, a novel method based on a single nucleotide polymorphism (SNP) assay was developed for identifying L. williamsii; this assay reliably detects SNPs within chloroplast DNA (rbcL, matK, and trnL-trnF IGS) and was validated for identifying Lophophora and L. williamsii simultaneously. The chloroplast DNA sequences from four L. williamsii and three L. diffusa plants were obtained and compared using DNA sequence data from approximately 300 other Cactaceae species available in GenBank. From this sequence data, a total of seven SNPs were determined to be suitable for identifying L. williamsii. A multiplex assay was constructed using the ABI PRISM^® SNaPshot™ Multiplex Kit (Applied Biosystems, Forster City, CA) to analyze species-specific SNPs. Using this multiplex assay, we clearly distinguished the Lophophora among 19 species in the Cactaceae family. Additionally, L. williamsii was distinguished from L. diffusa. These results suggest that the newly developed assay may help resolve crimes related to illegal distribution and use. This multiplex assay will be useful for the genetic identification of L. williamsii and can complement conventional methods of detecting mescaline.     

A scientometric analysis of knowledge spillover research

The Journal of Technology Transfer - This paper explores current trends in knowledge spillover research using scientometric analysis of all papers published in journals indexed in the Web of...     

Principal–Agent Dynamics and Electoral Manipulation: Local Risks,Patronage and Tactical Variation in Russian Elections, 2003–2012

Abstract

Why are some elections manipulated more severely than others, and why do the techniques used to manipulate them vary over time and space? This article addresses these related questions by showing that patronage resources—not incumbent popularity—make manipulation appealing to frontline agents, while local political conditions can make manipulation personally risky for them. Agents can mitigate these risks by adopting more dispersed forms of manipulation like vote-buying, rather than more centralised falsification. These hypotheses are tested using forensic analysis of electoral data from more than 90,000 precincts per election across Russia’s 83 regions, from 2003 to 2012.     

Postmortem Computed Tomography and Magnetic Resonance Imaging of Gunshot Wounds to the Neck

Postmortem magnetic resonance imaging (MRI) is rarely used for the radiologic assessment of gunshot injuries, although it has clear advantages over postmortem computed tomography (CT) with regard to the imaging of soft tissue injuries. Another benefit in using MRI is that lodged projectiles composed of nonferromagnetic material such as lead present only marginal metal artifacts compared with severe artifacts on CT. This case report presents CT and MRI findings in a case with two gunshot wounds to the neck: a perforating wound and a nonperforating wound with a lead bullet lodged in the cervical spine. The decedent underwent CT and MRI before the scheduled autopsy. A ring of radiopaque material under the dermis in the fatty tissue was identified at both entrance wounds on CT, which was indicative of contact shots. The perforating gunshot was clearly indicated on CT by bullet fragments along the wound channel through the perforated 6th cervical vertebra and the fractured cricoid cartilage at the exit wound. The second trajectory, however, was only assumed based on the presence of gunshot residues at the entrance wound and the position of the lodged bullet. The radiologic assessment was severely impeded by the metal artifacts on CT. Barely noticeable metal artifacts on MRI allowed for clear visualization of the soft tissue injuries and the ruptured medulla oblongata. Only MRI clarified the soft tissue injuries of the brainstem noninvasively, which could provide specific and graphic information on the rapidity of death and the incapacitation of the victim.