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Validity, Reliability, Accuracy, and Bias in Forensic Signature Identification

NCJ Number
Date Published
January 2014
1470 pages
Using a multi-method, multidisciplinary approach, this study tested the reliability, measurement validity, and accuracy of forensic document examiners' (FDEs') procedures for determining whether a signature was rendered by the person named in the signature.
The findings of this study provide significant empirical support for the validity and reliability of the foundations and methods of forensic document examination. The combination of objective eye-tracking measures and qualitative descriptive data demonstrated that FDEs used both top-down and bottom-up cognitive processes and an extensive range of information present in the signature specimens to reach their decisions. They provided evidence that FDEs engage in a systematic evaluation of significant features and assign meaning to these features based on common principles that are consistent across most trained examiners. This research supported the reliability and validity of the current methods of trained FDEs, even though the interpretation of handwriting features is a subjective decision. The study included an examination of the relationship between the number of certifications held by FDEs and their call accuracy. Although there was no statistically significant relationship between these factors, the most frequent comment about FDE certification was the belief that certification is necessary and should be pursued following training and prior to working with any court cases. Study methodology included a telephone/web survey that obtained information about the experience, education, and credentials of the FDE participants, along with their views about the strengths and weaknesses of education and training in forensic document examination. Following the survey, professional, fully qualified FDEs and a comparison sample of lay participants participated in a series of experimental laboratory protocols, during which eye-tracking equipment collected information about salient and diagnostic signature features, this was followed by interviews with participants regarding their decision making processes. Extensive tables and figures and approximately 100 references

Date Published: January 1, 2014