Skip to content

Covering the Basic Concepts Surrounding the Weight and Strength of Evidence

Research Area: Forensic Statistics

This CSAFE Center Wide webinar was presented on January 7, 2019 by Dr. Danica Ommen, CSAFE researcher and Assistant Professor at Iowa State University. Dr. Ommen has provided presentation slides for Part 1 and Part 2 and references.

 

Presentation Description: 

In this two-part presentation, we will focus on aspects of the forensic identification of source problems where the main question of interest is determining the origin of evidence with unknown source.  In order to solve this problem, we need to determine the value of the evidence with respect to two competing propositions for its origin by computing some type of “likelihood ratio.”  After we get this value of evidence, the idea is that it can be used to help someone make a decision.  In the case of a criminal trial, the decision would be regarding the guilt or innocence of the defendant.  However, there are many different ideas about what the “likelihood ratio” should look like and how to compute its value, especially in the face of uncertainty.  Often, we are uncertain about the statistical models we’ve chosen to describe the evidence.  In this presentation, we will discuss the basic definitions, as well as various computational strategies, for both the weight and the value of evidence.  In addition, we will review and discuss recent controversies surrounding the value of evidence.

 

Part 1

 

Part 2

Related Resources

Extracting Case-Specific Data from Validation Studies

Extracting Case-Specific Data from Validation Studies

This CSAFE webinar was held on May 10, 2022. Presenters: Steve Lund Statistical Engineering Division, NIST Hari Iyer Statistical Engineering Division, NIST Presentation Description: The legal and scientific communities agree…
Shining a Light on Black Box Studies

Shining a Light on Black Box Studies

This CSAFE webinar was held on April 22, 2022. Presenters: Dr. Kori Khan Iowa State University Dr. Alicia Carriquiry Iowa State University Presentation Description: The American criminal justice system heavily…
Sampling for Forensic Practitioners Short Course

Sampling for Forensic Practitioners Short Course

This three-session short course took place on March 25, April 1, and April 8, 2022. Recordings of completed sessions and practicum materials can be found below. Presenters: Alicia Carriquiry Director…
Modeling And iNventory of Tread Impression System (MANTIS): The development, deployment and application of an active footwear data collection system

Modeling And iNventory of Tread Impression System (MANTIS): The development, deployment and application of an active footwear data collection system

This CSAFE webinar was held on March 24, 2022. Presenters: Dr. Richard Stone Iowa State University Dr. Susan Vanderplas University of Nebraska, Lincoln Presentation Description: This webinar details the development,…