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Statistical Evaluation of Torn and Cut Duct Tape Physical End Matching

NCJ Number
Date Published
July 2011
90 pages

This study examined issues related to duct-tape physical end matching, with attention to criteria for describing the matching process, a protocol for training analysts in physical end matching, and statistically evaluating the associated error rates and overall accuracy.


The study confirmed that it is possible to use physical end matching to identify duct tape samples as matching or non-matching. Differences between analysts, brands, tape grades, tape color, and method of separation make varying contributions to misidentifications or inconclusive results. Brand and type grade are apparently more important than color in their effect on an analyst in correctly identifying duct-tape end matches. Scissor-cut tapes are apparently more difficult to analyze than hand-torn tapes, but there is no significant different in difficulty of analysis between hand-torn tape and tape cut with a box cutter knife. Consistent tearing conditions do not seem to influence an analyst's ability to identify duct-tape end matches. This study also showed the importance of peer review in duct-tape analysis and its ability to greatly reduce the number of misidentifications by analysts. The research examined 1,800 torn-tape specimens and 400 cut-tape specimens. The mean accuracy observed ranged from 98.58 to 100.00 percent for torn tape and from 98.15 to 99.83 percent for cut tape. The mean false-positive rate ranged from 0.00 to 0.67 percent for torn tape and from 0.00 to 3.33 for cut tape. The mean false-negative rate ranged from 0.00 to 2.67 percent for torn tape and was 0.33 percent for both types of cut tape. 64 exhibits, 10 references, a listing of venues in which the research findings have been disseminated, and appended supplementary information

Date Published: July 1, 2011