Une question de temps : apprentissage par problème dans un cours de police scientifique

Cet article présente l’évaluation du scénario pédagogique d’un cours portant sur la datation et la chronologie en police scientifique organisé autour d’un apprentissage par problèmes (APP). Ce cours est organisé en APP pour aborder autant les questions pratiques que les concepts théoriques avec les étudiants, remplaçant ainsi une partie d’un enseignement ex cathedra. L’évaluation du scénario a mis en évidence le degré élevé de motivation des étudiants lié aux types de problèmes proposés, issus de situations réelles. Ceux-ci ont appris à travailler en groupe et à interagir de manière systématique avec leur entourage, étant ainsi partenaire de leur apprentissage plutôt que récepteurs. Cette nouvelle façon d’aborder l’enseignement théorique a également permis à l’enseignante d’améliorer ses capacités à transmettre les compétences visées au long du processus mis en place et ceci tout particulièrement en terme de transfert de la théorie vers la pratique.This article presents the evaluation of a problem-based learning (PBL) scenario introduced in a forensic course on dating and reconstruction of chronologies. The educational project comprises replacing part of the traditional lecture by PBL for practical reasons as well as conceptual. Evaluating the scenario highlighted that students’ motivation is enhanced by the problems put foward, stemming from real situations similar to those students will encounter in their future professional environment. Students also learned to work in groups and interact with their colleagues, thus being partners of their learning instead of sole receivers. This new approach of teaching concept and theories also improved the teacher capacities in enabling the learning process, and in particular transfering theory to practice

Une question de temps : apprentissage par problème dans un cours de police scientifique

Cet article présente l’évaluation du scénario pédagogique d’un cours portant sur la datation et la chronologie en police scientifique organisé autour d’un apprentissage par problèmes (APP). Ce cours est organisé en APP pour aborder autant les questions pratiques que les concepts théoriques avec les étudiants, remplaçant ainsi une partie d’un enseignement ex cathedra. L’évaluation du scénario a mis en évidence le degré élevé de motivation des étudiants lié aux types de problèmes proposés, issus de situations réelles. Ceux-ci ont appris à travailler en groupe et à interagir de manière systématique avec leur entourage, étant ainsi partenaire de leur apprentissage plutôt que récepteurs. Cette nouvelle façon d’aborder l’enseignement théorique a également permis à l’enseignante d’améliorer ses capacités à transmettre les compétences visées au long du processus mis en place et ceci tout particulièrement en terme de transfert de la théorie vers la pratique.This article presents the evaluation of a problem-based learning (PBL) scenario introduced in a forensic course on dating and reconstruction of chronologies. The educational project comprises replacing part of the traditional lecture by PBL for practical reasons as well as conceptual. Evaluating the scenario highlighted that students’ motivation is enhanced by the problems put foward, stemming from real situations similar to those students will encounter in their future professional environment. Students also learned to work in groups and interact with their colleagues, thus being partners of their learning instead of sole receivers. This new approach of teaching concept and theories also improved the teacher capacities in enabling the learning process, and in particular transfering theory to practice

Evaluation of infrared spectra analyses using a likelihood ratio approach: A practical example of spray paint examination

Depending on the forensic disciplines and on the analytical techniques used, Bayesian methods of evaluation have been applied both as a two-step approach (first comparison, then evaluation) and as a continuous approach (comparison and evaluation in one step). However in order to use the continuous approach, the measurements have to be reliably summarized as a numerical value linked to the property of interest, which occurrence can be determined (e.g., refractive index measurement of glass samples). For paint traces analyzed by Fourier transform infrared spectroscopy (FTIR) however, the statistical comparison of the spectra is generally done by a similarity measure (e.g., Pearson correlation, Euclidean distance). Although useful, these measures cannot be directly associated to frequencies of occurrence of the chemical composition (binders, extenders, pigments). The continuous approach as described above is not possible, and a two-step evaluation, 1) comparison of the spectra and 2) evaluation of the results, is therefore the common practice reported in most of the laboratories. Derived from a practical question that arose during casework, a way of integrating the similarity measure between spectra into a continuous likelihood ratio formula was explored. This article proposes the use of a likelihood ratio approach with the similarity measure of infrared spectra of spray paints based on distributions of sub-populations given by the color and composition of spray paint cans. Taking into account not only the rarity of paint composition, but also the "quality" of the analytical match provides a more balanced evaluation given source or activity level propositions. We will demonstrate also that a joint statistical-expertal methodology allows for a more transparent evaluation of the results and makes a better use of current knowledge

Evaluation and Examination of a Possible Shoe-polish Trace in a Hold-up Case

In this article, we show how the Bayesian framework can be applied to a hold-up case involving a possible shoe-polish trace according to one of the parties. This article highlights the importance of interpreting data from the beginning of the examination through the preassessment steps. Once a set of alternative propositions in agreement with the information provided by the parties is chosen, one can establish what is needed in the case. Here, limited data were available to assign factors such as transfer and rarity of the traces. Consequently, we showed how specific case-tailored experiments provide meaningful data for evaluation. In this case, the police had observed a trace on the jacket of a person who reported to have been pushed with the offender's gun during the hold-up attempt. When the jacket was submitted to our laboratory, the exact nature of the trace was unknown. Particles from this trace were collected and analyzed by stereomicroscopy, microscopy, and infrared spectroscopy. The obtained results supported that this trace was waxy material. The literature dealing with the analysis of waxy materials generally uses solvent extraction-based methods. Here, as our analytical sequence allowed a good discrimination of different waxy products of known origin, we considered that this methodology was adequate. Moreover, it did not involve any extraction step that could lead to undesired compounds from the substrate (e.g., dyes and additives). This article therefore suggests an alternative analytical sequence for the analysis of such material in casework

Une question de temps : apprentissage par problème dans un cours de police scientifique

This article presents the evaluation of a problem-based learning (PBL) scenario introduced in a forensic course on dating and reconstruction of chronologies. The educational project comprises replacing part of the traditional lecture by PBL for practical reasons as well as conceptual. Evaluating the scenario highlighted that students’ motivation is enhanced by the problems put foward, stemming from real situations similar to those students will encounter in their future professional environment. Students also learned to work in groups and interact with their colleagues, thus being partners of their learning instead of sole receivers. This new approach of teaching concept and theories also improved the teacher capacities in enabling the learning process, and in particular transfering theory to practice