Universal Definition of ACE-V

A Universal Definition of ACE-V used in formal comparative methodology

          ACE-V is an acronym for the established formal methodological comparison process that is analogous to the scientific method.  The purpose of the ACE-V comparison methodology is to individualize or exclude impressions or objects as having originated from an identical source or as being one-in-the-same.  The letters “ACE” are for Analysis, Comparison, and Evaluation.  “V” is the hypothesis-testing or verification phase of the process in which another qualified examiner reinitiates the ACE process in order to see if the original hypothesis of individualization or exclusion is valid from their expert perspective, thus supporting or refuting the conclusions of the original examiner.

ACE-V’s Premises and Processes

The premise and process of the ACE-V methodology relies on the discovery of relevant and unique information that can be used in the comparison and prediction aspects regarding particular information sets.  The process as a whole involves the sequential accumulation and correlation of relevant information that provides for a hypothesis of Individualization, Exclusion, or Inconclusive results.  Inconclusive is where there is insufficient information to individualize or exclude the item, impression, or mark in question.

The analysis stage of the process is a fundamental inventory of available informational components to be used in a comparison.  This information is analyzed for its quantitative and qualitative aspects, as well as its specificity and relevance.

The comparison stage involves the prediction of specific information, which has been identified and spatially located within one impression or object, then predicted to exist within the comparison exemplar.  The comparison itself reveals whether this prediction is valid, invalid, or inconclusive to include the fact that the particular information cannot be compared.  A lack of available comparison area may be due to excessive distortion of information or there is an unavailability of a particular comparison area in the second information set. 

The evaluation in the ACE-V methodology is, in part, a combined assessment of the previous information generated from the first two stages of the ACE-V process.  This assessment relies on accurate training, experience, comprehension of the principles of individualization, comparison bias, and of the ACE-V methodology itself.   The information studied is questioned to determine if it is sufficient for comparison, sufficient in its predictive comparison aspects when considering relevant qualitative and quantitative values and the information can be properly understood within the context of established science. At the completion of the evaluation stage, a formal hypothesis is offered. 

The final stage in the ACE-V methodology is verification.  Verification is a two-part process of peer reviewed hypothesis and failure criterion testing, in which a second qualified examiner examines the established documentation and/or hypothesis and utilized methodology prior to reinitiating the ACE process to test the original hypothesis.  Verification is the culmination (phase transition) of the two examiner’s formal hypotheses into a single verified hypothesis by way of concurrence.  The original hypothesis is stated to be validated by concurring expert opinion.  Individualization (Identification) is the product of the entire ACE-V process properly applied, in that the two formal hypotheses are in agreement. 

            Non-concurring results produced by the ACE-V process can be due to clerical errors, improperly applied ACE-V methodology, variances in expertise, and the discovery of hypotheses error.  When insufficient information is present or discovered, it may not be possible to formally individualize or exclude particular information sets with that utilized information.  The proper result is a conclusion of Inconclusive.  This may include the fact that; potentially matching information sets have not yet been discovered by the investigative search process prior to ACE-V, or that there is insufficient information present to formally and reliably exclude the practical possibility of a match.  In such a case, sequential expert analysis is recommended.

Craig A. Coppock   12-11-2006
Updated 12-12-2017
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Current Note:  This “Universal” version of the well-established ACE-V methodology is an attempt to create a single comprehensive reference of the ACE-V methodology that can be used for all the forensic comparison sciences.  This universal version was built with input and feedback from many examiners from the USA and Canada over several years.  Such a standard reference will also allow focused development of relevant and useful guidelines and Information Theory research that will further the forensic comparison sciences. Also see; Science of Elimination Utilizing ACE-V in this blog dated April 2006.  

     Information Theory, in which ACE-V is being researched as a sub-component, allows for a relevant level of error correction in the analytical process.  With cognitive functions, the various system phases within Information Theory can be formatted to promote error minimization and correction.  This can take multiple forms such as research, protocol enhancement, specific and general analysis, testing, experience, training, and other quality control measures.  Periodic review of the process performance can reinforce effective error mitigation.  

     Also see the related post "Scientific Method; Information Theory's Foundation to the Scientific Method" for comprehensive insights on the introduction of error in this process.  To properly understand ACE-V we must also understand the Scientific Method and ultimately its foundation Information Theory. 

This article posted to the blog "Fingerprint Individualization | ACE-V | Scientific Method" at:  http://fingerprintindividualization.blogspot.com. Related information is also posted to ResearchGate.com and Academia.edu