RAC Heat Map
[Updated 04-Sep-2019; previous version accessible at www.4n6chemometrics.com/database_archive]
The Speir Research Group in the Department of Forensic and Investigative Science at West Virginia University currently houses a database of over 2000 shoes. To date, 1300 shoes have been fully analyzed, identifying a total of 72,306 randomly acquired characteristics (RACs). These RACs have been classified based on outsole location and shape; shape classes include variable, linear and compact geometries. This webpage provides the user with access to an interactive heat map detailing RAC frequency in terms of location and shape for a normalized shoe.
In the following frequency table, numerical values in the shaded row remain constant regardless of the user's interaction with the heat map, displaying data associated with total RAC count for the entire database (regardless of cell location). Conversely, the three unshaded rows automatically update to display RAC count and frequency for individual cells (5 mm x 5 mm) selected by the user (please select a location/cell of interest using a left mouse click). As of September 2018, we also report chance association (co-occurrence and indistinguishability), modified by tread elements. For more information about data included in the table, please see the bottom of this page for further description.
Horizontal Cell # | Vertical Cell # |
---|---|
- | - |
Variable | Linear | Compact | Any Shape | |
---|---|---|---|---|
All RACs in Database | 28,236 | 21,363 | 22,707 | 72,306 |
All RACs in Cell | - | - | - | - |
Chance of Finding RAC in Cell | - | - | - | - |
Unique Shoes Contributing to RAC Count | - | - | - | - |
Shoes with Tread Contact in Cell | - | - | - | - |
Chance of RAC Co-Occurrence | - | - | - | - |
Chance of RAC Indistinguishability | - | - | - | - |
Visually Evaluated / Total RAC Pairs | - | - | - | - |
Similarities & Likelihood Ratios |
Few RACs Many RACs