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OSAC Preferred Terms

Term Definition

Administrative

Review

An evaluation of the report and supporting documentation for consistency

with organizational policies and for editorial correctness.

Authentication,

Biometric

Process of assessing a level of confidence in identify or identification.

Bias, Cognitive A set of influences that may affect the reliability and validity of one’s 

observations and conclusions.

Bias, Confirmation The tendency to search for data or interpret information in a manner that

supports one’s preconceptions, expectations, or desires.

Bias, Contextual A deviation in human judgment caused by exposure to information that is

either irrelevant to the judgmental task or inappropriate for consideration.

Bias, Statistical A systematic tendency for estimates or measurements to be above or below 

their true values.

NOTE 1: Statistical bias arises from systematic as opposed to random error. NOTE 

2: Statistical bias can occur in the absence of prejudice, partiality, or

discriminatory intent.

Chain of custody Chronological record of the handling and storage of an item from its point of

collection to its final return or disposal.

Competency

testing

Evaluation of a person’s knowledge and ability to perform work before

authorization to do so independently.

Control Material of established origin used to evaluate the performance of a test or 

comparison. Or a test performed to demonstrate that a test method works 

correctly and to ensure that data are valid. Positive controls confirm that the 

procedure will produce the expected result. Negative controls confirm that the

procedure does not produce an unintended result.

Exclusion A result that compared items did not originate from the same source, are not 

the same substance, or do not share the same composition or classification,

based on an exclusionary difference.

Exclusionary 

Difference 

A difference in one or more characteristics between compared items that is 

sufficient to determine that the compared items did not originate from the 

same source, are not the same source, or do not share the same composition 

or classification.

NOTE: What is sufficient depends on the performance and limitations of the

method used on the material in question.
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Term Definition

Forensic Related to methods, techniques and processes used to establish conclusions 

and/or opinions, facts and findings which can be used for legal proceedings.

Forensic Science The application of scientific principles and techniques to matters of criminal

justice especially as relating to the collection, examination, and analysis of 

physical evidence.

Forensic Services Activities included in the collection, examination, and analysis of items and 

reporting of observations and opinions for matters of criminal justice, or for 

regulatory, or legal proceedings.

Forensic Service 

Provider 

An organization or individual that provides forensic services.

Forensic Science 

Service Provider

An organization or individual that provides forensic science services.

Interlaboratory 

Comparison

Organization, performance, and evaluation of measurements or tests on the 

same or similar items by two or more laboratories in accordance with

predetermined conditions.

Interpretation Explanations for the observations, data, and calculations.

Intralaboratory 

comparison

Organization, performance, and evaluation of measurements or tests on the 

same or similar items within the same laboratory in accordance with 

predetermined conditions.

Observation Recognizing and noting an occurrence.

Opinion View, judgment, belief – takes into consideration other information in addition

to observations, data, calculations, and interpretations.

Peer review An independent evaluation of a scientific, professional, or academic

manuscript or publication by a qualified second party to evaluate the claims, 

methods, interpretations, and conclusions.

Performance 

Monitoring

The ongoing process of evaluating a forensic service provider’s ability to perform 

work. Examples include quality control measures, observation, case review, 

retesting, blind testing, testimony monitoring, intra- or interlaboratory 

comparisons, and proficiency testing. 

Proficiency testing Evaluation of participant performance against pre-established criteria by

means of interlaboratory comparisons.

Reliability,

Evidentiary/Legal

Credibility and trustworthiness of proffered evidence.

Reliability,

Statistical

Consistency of results as demonstrated by reproducibility or repeatability.

Repeatability Extent of agreement between more than one result determined in the same 

place, by the same person, on the same equipment, in the same way, at similar

times.

Replicability See “Reproducibility”.

Reproducibility Extent of agreement between more than one result determined under any

combination of different conditions.
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For a complete list of forensic science terms organized by discipline, please visit the OSAC 

Lexicon (www.nist.gov/osac/osac-lexicon).

Term Definition

Result The product of the forensic service provider. This term is broad and includes

observations, data, calculations, interpretations, and opinions.

Technical Review A qualified second party’s evaluation of reports, notes, data, and other

documentation to ensure there is appropriate and sufficient support for the 

actions, results, conclusions, opinions and interpretations.

Validation A process of evaluating a system, method, or component to determine that

requirements for an intended use or application have been fulfilled.

Verification,

Analytical

Performing subsequent testing to ascertain if the results are concordant.