This "in-brief" report summarizes the objectives and material of the workshop on Statistical Interpretation Software for Friction Ridge Skin Impression (FRStat), which was part of the Impression, Pattern and Trace Evidence Symposium (IPTES) on January 22-25, 2018, in Arlington, VA, hosted by the Forensic Technology Center of Excellence.
The 4-hour workshop provided an overview of the FRStat software, including its development, validation, use, interpretation, and limitations. The workshop began with a review of basic statistical concepts, such as the difference between descriptive and inferential statistics, how to build histograms, and how to calculate probabilities within a distribution. The workshop then described how these concepts were applied in the development of the FRStat software. Participants were guided through examples, so as to better understand how to use FRStat, how to interpret its output, and how to present the results appropriately in reports or testimony. Suggestions were offered on the implementation of FRStat in forensic laboratories, including recommendations for lab policies and procedures, such as how to implement it in attendees' home laboratories. A discussion of FRStat's limitations notes that it must be internally validated for use before adoption in a laboratory; specific limitations are outlined. It is recommended that agencies considering the implementation of FRStat in their casework also consider implementing appropriate policies and procedures for its use. Suggestions recommended by FRStat's developers are offered. FRStat is currently freely available to U.S. government forensic laboratories (federal, state, and local). The source website is provided in this report. Online access to two reference websites
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