Attend this seminar to earn credits to renew your SAFE membership for 2024 and renew your CFDE certification.

Speaker: Ms. Graziella Pettinati

In 1997, after sixteen years of teaching, Graziella Pettinati made a 180° turn and opened her first handwriting business office. Since then, she has developed in Forensic Examination. Speaker, author and businesswoman, Graziella is distinguished both in Quebec and abroad.

Accepted as an expert witness and has testified since 2001 before civil, criminal, administrative and arbitration courts. Appointed by the Court of Quebec. Has testified more than 60 times.

Topic: Opinion Scales

Abstract

There are many “opinion scales” used in the field of Handwriting Examination. The fact that most of the “opinion scales” are ordinal, or strength scales present some problems because the FDEs have difficulty to explain clearly the difference between “highly probable” and “probable”. As we all know, the levels of the scales are not quantified. There are often differences between examiners in how they view the degree of differences between the opinion levels. Some FDE will make their opinion based on the rarity of features and others will refer to the strength of evidences perceived in the handwriting.

The use of the conventional scales (5, 7 or 9 levels) is often inconsistent across FDEs. Using the modular and likelihood ratio-based approaches is a way to minimize the problems between different FDEs.

When using the likelihood ratio scale (Modular Approach) the FDE is expressing the strength of the evidence in terms or two or more mutually exclusive hypothesis. The opinion is expressed as the strength of support for one hypothesis over one or more mutually competing hypothesis.

This concept will be illustrated by case studies.