ICFIS 2014 — Teaching the Logical Approach for Evidence Evaluation to FDEs

This year’s International Conference on Forensic Inference and Statistics (ICFIS) is being held at Leiden University in the Netherlands.  ICFIS 2014 logoICFIS conferences are always very good and this is the 9th such event.  I am hoping to attend to present my thoughts on the topic of education relating to the logical (a.k.a. likelihood-ratio or LR) approach to evidence evaluation. Over the last few years I have given several one and two-day seminars and workshops on this topic, mainly for Forensic Document Examiners (FDEs) though the subject matter relates to all disciplines equally.  Those workshops have been great and provided a relatively unusual opportunity to learn about how fully trained examiners come to grips with a complicated and difficult topic.  One that is fundamental to FDE work.
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ASQDE “Conclusions and Logical Inference” Workshop 2013

This year the Annual General Meeting of the American Society of Questioned Document Examiners (ASQDE) ASQDE 2013 is being held in Indianapolis, Indiana on August 24 through 29, 2013. In keeping with the theme, “Demonstrative Science: Illustrating Findings in Reports and Court Testimony”, I will be presenting a one-day workshop entitled “Conclusion Scales and Logical Inference” on Sunday, August 25.
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Introduction to the Logical Approach to Evidence Evaluation

It is absolutely true that most forensic scientists want to be completely logical, open and transparent in their approach to the evaluation of evidence.  Further, I am sure that most document examiners believe this is exactly what they are achieving when they apply the procedures outlined in various traditional textbooks or the SWGDOC/ ASTM standards; for example, the SWGDOC Standard for Examination of Handwritten Items.

Given the very understandable desire to be logical, I find it strange that so many people have a negative attitude towards anything Bayesian in nature.  After all, an approach to evidence evaluation conforming to the Bayesian philosophy or approach would be quite literally the embodiment of logic (more specifically, probabilistic logic).

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Accuracy and precision

The terms accuracy and precision are often confused or misunderstood.  But every scientist, forensic or otherwise, should understand what they mean.  In simple terms, ‘accuracy’ relates to how closely the value comes to the real score or true value (being ‘on target’). ‘Precision’, on the other hand, relates to the consistency of the value in repeated testing.  Any given test, statistic or process may produce results that are one or the other, both or neither.
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