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Digital Handwriting Analysis of Characters in Chinese Patients with Mild Cognitive Impairment
05:58

Digital Handwriting Analysis of Characters in Chinese Patients with Mild Cognitive Impairment

Published on: March 11, 2021

Score-based likelihood ratios for handwriting evidence.

Amanda B Hepler1, Christopher P Saunders, Linda J Davis

  • 1Document Forensics Laboratory (MS 1G8), George Mason University, Fairfax, VA 22030, USA. abhepler@innovativedecisions.com

Forensic Science International
|February 3, 2012
PubMed
Summary
This summary is machine-generated.

Different methods for generating denominator databases in forensic likelihood ratio calculations can lead to significantly different conclusions. This study compares three approaches, highlighting the impact of subjective choices on evidence evaluation.

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Area of Science:

  • Forensic Science
  • Statistical Inference
  • Pattern Recognition

Background:

  • Score-based likelihood ratios are increasingly used in forensic analysis.
  • Modeling score behavior under competing source propositions requires specific assumptions for numerator and denominator distributions.
  • Generating denominator databases for differing source items presents ambiguities.

Purpose of the Study:

  • To compare three distinct methods for generating denominator databases in score-based likelihood ratios.
  • To illustrate the impact of subjective choices in denominator database generation on forensic inferences.
  • To analyze the effect of differing item types on denominator database construction.

Main Methods:

  • Comparison of three denominator database generation methods: (1) known item with random database items, (2) unknown item with random database items, (3) two random database items.
  • Application of methods to a dataset of over 400 cursive handwriting samples.
  • Analysis of resulting score-based likelihood ratios using rates of misleading evidence and Tippet plots.

Main Results:

  • The three compared methods often produced differing conclusions for the same pair of evidence items, with disagreement rates from 0.005 to 0.48.
  • The choice of denominator database generation significantly impacts the resulting score-based likelihood ratios.
  • The three score-based likelihood ratios exhibit theoretically different behaviors from each other and from traditional likelihood ratios.

Conclusions:

  • Subtle modifications in propositions for denominator database generation can substantially alter inferences drawn from forensic evidence.
  • The subjective nature of denominator database construction requires careful consideration in forensic likelihood ratio analysis.
  • The choice of method significantly affects the interpretation and reliability of forensic evidence evaluation.