The Evidential Value of the Comparison of Paint Flakes from Sources other than Vehicles

Tippett, Christine; Emerson, V.J.; Fereday, M.J.; Lawton, F.; Richardson, A.; Jones, Lisa; Lampert, Miss S.M.

doi:10.1016/s0015-7368(68)70442-4

Cited by 70 publications

(20 citation statements)

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“…16, called the Tippett plot, was proposed by Evett and Buckleton in the field of interpretation of the forensic DNA analysis (20). The Tippett plot, first used in forensic analysis of paints (21), refers to ''within-source comparison'' and ''between-sources comparison.'' The functions in the Tippett plot represent the inverse cumulative distribution functions, and are also known as reliability functions.…”

Section: Strength Of Evidencementioning

confidence: 99%

On the Discriminability of the Handwriting of Twins

Srihari

Huang

Srinivasan

2008

Journal of Forensic Sciences

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As handwriting is influenced by physiology, training, and other behavioral factors, a study of the handwriting of twins can shed light on the individuality of handwriting. This paper describes the methodology and results of such a study where handwriting samples of twins were compared by an automatic handwriting verification system. The results complement that of a previous study where a diverse population was used. The present study involves samples of 206 pairs of twins, where each sample consisted of a page of handwriting. The verification task was to determine whether two half-page documents (where the original samples were divided into upper and lower halves) were written by the same individual. For twins there were 1236 verification cases-including 824 tests where the textual content of writing was different, and 412 tests where it was the same. An additional set of 1648 test cases were obtained from handwriting samples of nontwins (general population). To make the handwriting comparison, the system computed macro features (overall pictorial attributes), micro features (characteristics of individual letters), and style features (characteristics of whole-word shapes and letter pairs). Four testing scenarios were evaluated: twins and nontwins writing the same text and writing different texts. Results of the verification tests show that the handwriting of twins is less discriminable than that of nontwins: an overall error rate of 12.91% for twins and 3.7% for nontwins. Error rates with identical twins were higher than with fraternal twins. Error rates in all cases can be arbitrarily reduced by rejecting (not making a decision on) borderline cases. A level of confidence in the results obtained is given by the fact that system error rates are comparable to that of humans (lower than that of lay persons and higher than that of questioned document examiners [QDEs]).KEYWORDS: forensic science, questioned document examination, handwriting processing, document analysis, writer verification, twins studyThe distinctiveness of each person's handwriting has long been intuitively observed. Methods have been developed for a human expertise of handwriting matching over many decades (1-5). Yet there is a need for studies in the quantitative assessment of the discriminative power of handwriting particularly for the acceptance by the courts of evidence provided by questioned document examiners (QDE). In a previous study of handwriting individuality (6), we reported on the discriminability of handwriting of a diverse population from across the United States. The present paper reports on a complementary study of the discriminatory power of handwriting when the population consists of a cohort group consisting of twins. Both the previous study and the current study are based on automated methods for handwriting comparison. The current study uses algorithms that are updated with respect to the types of handwriting features that are computed.The necessity of studying cohort groups such as twins has been considered to be i...

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Section: Strength Of Evidencementioning

confidence: 99%

On the Discriminability of the Handwriting of Twins

Srihari

Huang

Srinivasan

2008

Journal of Forensic Sciences

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“…Instead of using binary decisions a range of interpreted results is always better and more practical from the QDE point of view. Based on the Tippet plot [10] (inverse CDF plot) and the CDF plot we develop a scheme for calibrating the LLR scores. The CDF and inverse CDF for same and different writer LLRs (considering 12 macro features and 62 micro features) is shown in Figure 8 (c).…”

Section: Evaluating the Strength Of Evidencementioning

confidence: 99%

Biometric and Forensic Aspects of Digital Document Processing

Srihari

Huang

Srinivasan

et al. 2007

Digital Document Processing

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Abstract. Signatures and handwriting have long played a role in dayto-day business transactions and in forensics, e.g., to authenticate documents, as evidence to establish crime or innocence, etc. The individuality of handwriting and signatures is the basis for their relevance to authentication and forensics. This very individuality makes them also potentially useful as a biometric modality. This chapter is concerned with automatic methods for verifying the writership of handwritten documents and signatures. The discussion consists of the individuality of handwriting, image pre-processing and interactive tools for forensic document examination, discriminating characteristics of handwriting, a statistical model of writer verification, and application of the model to signature verification.

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“…Based on the work by Tippett et al [19], in [5] a useful representation for between-source comparisons in any forensic discipline, the so-called Tippett plots, is provided, representing proportion of cases with "LR values greater than…" (figure 4). Then, we will draw in each Tippett plot simultaneously two curves, one for the C hypothesis (the pattern belongs to the suspect -targets), where the system should provide high LR values (LR>>1), and another one for the C hypothesis (the pattern does not belong to the suspect -non-targets), where the system should provide low LR values (LR<<1).…”

Section: Assessment Of Forensic Biometric Systemsmentioning

confidence: 99%