David H. Kaye’s “Forensic Science, Statistics & the Law”

David H. Kaye (DHK) is one of my favourite writers. He is truly prolific and always manages to provide great insights for the reader. His grasp of statistics, logic, and the law is second-to-none, and his ability to communicate those very challenging topics to his audience is equally impressive.

As a mini introduction, David “…is Distinguished Professor, and Weiss Family Scholar in the School of Law, a graduate faculty member of Penn State’s Forensic Science Program, and a Regents’ Professor Emeritus, ASU.” If you would like to see a list of his publications check out http://personal.psu.edu/dhk3/cv/cv_pubs.html 

Yes, DHK has written many things on many topics.1  But I would like to focus on his less formal writings from his blog  Forensic Science, Statistics & the Law.

Below you will find a selection of posts that I find particularly interesting, each for its own reason.  I plan to do a mini-review of each of these to explain how they relate to my view of the logical approach to evidence evaluation (among other things).  Unlike DHK it seems to take me forever to write something worthy of posting so please don’t expect anything in the near future.  However, I will add a link to my work as I get them done.  In the meantime I recommend you take a few minutes to review David’s writings, starting with the following: 

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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