FINAL by: OSAC Program Office; Version 2, January 13, 2020 1

OSAC RESEARCH NEEDS ASSESSMENT FORM

Title of research need: Validation of Interpretation Scales for Footwear and Tire Forensics

Describe

the need:

A footwear/tire interpretation scale may include one or more levels each of (1) support for 

the same source, (2) support for different sources, and (3) inconclusive. For example, the 

current SWGTREAD Range of Conclusions standard has two levels related to support for 

different sources, four levels related to support for the same source, and one level 

describing inconclusive as “lacks sufficient detail.” Note: The OSAC Footwear and Tire 

Subcommittee is currently revising this standard. Therefore, it is recommended that this 

research be performed after a new articulation standard has been proposed by OSAC. 

Any interpretation scale requires validation. In general, validation requires two activities: 

(1) performance testing -- the collection and analysis of test data to understand how well 

something performs, and (2) application of performance thresholds -- prespecifying 

minimum acceptable performance requirements and assessing whether these 

requirements have been met. The second activity involving prespecifying minimum 

acceptable requirements may be difficult because all the stakeholders, including 

representatives of the general public, may need to decide what the minimum requirements 

are based on what is acceptable in a criminal-justice system. 

Validation of an interpretation scale consists of three elements: (1) determining to what 

extent the interpretation language represents the opinions reached by examiners, (2) 

determining the accuracy of examiners’ source interpretations when using the scale (in the 

form of false positive and false negative error rates) and whether this accuracy changes 

with different interpretation scales, and (3) determining how understandable the 

conclusions are to various stakeholders including lay persons, defense attorneys, 

prosecutors, judges, and investigators, and whether stakeholders infer the same meaning 

as that intended to be conveyed by the expert. 

The second element above, i.e., determining error rates, is usually the result of “black-box” 

studies. Such studies are currently being undertaken but would also be part of the 

validation process for a particular interpretation scale.

Keyword(s): Footwear, Tire, Conclusion Scale, Interpretation Scale, Validation, Scientific Basis

Submitting subcommittee(s): Footwear & Tire Subcommittee Date Approved: October 24, 2022
FINAL by: OSAC Program Office; Version 2, January 13, 2020 2

Background Information:

1. Does this research need address a gap(s) in a current or planned standard? (ex.: Field identification system 

for on scene opioid detection and confirmation)

Articulation standard 

2. Are you aware of any ongoing research that may address this research need that has not yet been published 

(e.g., research presented in conference proceedings, studies that you or a colleague have participated in but 

have yet to be published)?

3. Key bibliographic references relating to this research need: (ex.: Toll, L., Standifer, K. M., Massotte, D., eds. 

(2019). Current Topics in Opioid Research. Lausanne: Frontiers Media SA. doi: 10.3389/978-2-88963-180-3)

• “Range of Conclusions Standard for Footwear and Tire Impression Examinations.” SWGTREAD Scientific Working 

Group for Shoeprint and Tire Tread Evidence, March 2013, 

https://treadforensics.com/images/swgtread/standards/current/swgtread_10_conclusions_range_201303.pdf .

• Thomas Busey, Morgan Klutzke, Alyssa Nuzzi, John Vanderkolk. Validating strength-of-support conclusion scales 

for fingerprint, footwear, and toolmark impressions. J. Forensic Sci, Vol. 67, No. 3 (2021) 936-954. 

doi.org/10.1111/1556-4029.15019.

• Thompson, William (2018) "How Should Forensic Scientists Present Source Conclusions?," Seton Hall Law Review: 

Vol. 48 : Iss. 3 , Article 9. Available at: https://scholarship.shu.edu/shlr/vol48/iss3/9 

• Bradford T. Ulery, R. Austin Hicklin, JoAnn Buscaglia, and Maria Antonia Roberts. “Accuracy and reliability of 

forensic latent fingerprint decisions.” Proceedings National Academy of Sciences May 10, 2011 108 (19) 7733-

7738; https://doi.org/10.1073/pnas.1018707108

• Jacqueline A. Speir, Nicole Richetelli, Lesley Hammer. Forensic Footwear Reliability: Part I—Participant 

Demographics and Examiner Agreement. J Forensic Sci, Vol. 65, No. 6 (2020). doi: 10.1111/1556-4029.14553

• Nicole Richetelli, Lesley Hammer, and Jacqueline A. Speir. Forensic Footwear Reliability: Part II—Range

 of Conclusions, Accuracy, and Consensus. J Forensic Sci, Vol. 65, No. 6 (2020). doi: 10.1111/1556-4029.14551

• Nicole Richetelli, Lesley Hammer, and Jacqueline A. Speir. Forensic Footwear Reliability: Part III—Positive

 Predictive Value, Error Rates, and Inter-Rater Reliability. J Forensic Sci, Vol. 65, No. 6 (2020). doi: 10.1111/1556- 

 4029.14552

4. Review the annual operational/research needs published by the National Institute of Justice (NIJ) at 

https://nij.ojp.gov/topics/articles/forensic-science-research-and-development-technology-working-groupoperational#latest? Is your research need identified by NIJ?

Yes.

5. In what ways would the research results improve current laboratory capabilities?

An interpretation scale that’s appropriately validated would allow for universal application in laboratory procedures 

when reporting source interpretations for evidence evaluation.
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6. In what ways would the research results improve understanding of the scientific basis for the 

subcommittee(s)?

The research results would provide a much better scientific, quantitative, empirically tested understanding of 

interpretation scales. This would provide greater confidence that a particular scale will result in reliable outcomes, as 

well as provide a methodology for continued development and improvement of interpretation scales.

7. In what ways would the research results improve services to the criminal justice system?

A validated interpretation scale would result in interpretations and their articulation that are more reliable and better 

understood by stakeholders who are non-experts, including triers of fact. This will result overall in better decisions in 

the criminal-justice system.

8. Status assessment (I, II, III, or IV): I

Major gap in 

current 

knowledge

Minor gap in 

current 

knowledge

No or limited

current research is 

being conducted I III

Existing current 

research is being 

conducted II IV

This research need has been identified by one or more subcommittees of OSAC and is being provided as an 

informational resource to the community.