ENFSI Verbal Scale
Definition
A standardised table published by the European Network of Forensic Science Institutes that maps ranges of LR values to verbal expressions of evidential support, from 'limited' (LR 1 to 10) to 'extremely strong' (LR greater than 1,000,000). Reduces inconsistency in how numerical conclusions are communicated to courts.
- Created by
- European Network of Forensic Science Institutes (ENFSI)
- Purpose
- Convert likelihood ratios to plain-language phrases for court communication
- Scope
- Standardized across ENFSI forensic science disciplines
Common questions
What is the ENFSI verbal scale and why do forensic scientists use it?+
The ENFSI verbal scale translates likelihood ratio (LR) numbers into plain language so courts can understand forensic evidence strength. Instead of saying 'LR equals 500,' an expert says 'very strong support.' This shared scale works across ENFSI disciplines, making it easier for judges and juries to grasp the meaning.
What are the main levels on the ENFSI scale?+
The scale ranges from 'limited support' (LR 1-10) through 'moderate,' 'moderately strong,' and 'strong,' up to 'very strong' and 'extremely strong support' (LR above 10,000). Each verbal phrase maps to a specific range of LR values, so the language is tied to the science.
Can the ENFSI scale be used for different types of evidence?+
Yes. The scale is standardized across ENFSI disciplines, so it works for speaker recognition, geological evidence, and other forensic fields. This consistency helps courts understand evidence comparisons across different types of analysis.
Related terms
- Background Population Database
- A corpus of speaker recordings used to calibrate the LR in a forensic comparison. Must be matched to the case in language,...
- BATVOX
- A commercial automated speaker recognition system (originally Agnitio, later Nuance Communications) widely used in operational forensic casework in Europe and Latin America....
- Between-Source Variation
- The variation observed among samples from different locations in the reference population. Used to estimate the probability of the observed similarity under...
- C_llr (Log-Likelihood Ratio Cost)
- A proper scoring rule measuring the calibration quality of a speaker recognition system's LR outputs; a well-calibrated system has C_llr close to...
- Denominator Hypothesis
- The defence hypothesis under which the LR denominator is calculated. Typically: the questioned sample comes from some other location within the relevant...
- ENFSI BPM
- The ENFSI Best Practice Manual for Forensic Comparison of Speech (2015, rev. 2022); the operational standard for speaker comparison in European forensic...
- Equal Error Rate (EER)
- The point on a classifier's detection error tradeoff curve where the false accept rate equals the false reject rate. Lower EER indicates...
- Evaluative Reporting
- A framework for expressing forensic conclusions in terms of the probability of the evidence given the prosecution hypothesis versus the defence hypothesis...
- I-Vector
- A fixed-length low-dimensional speaker representation extracted by projecting a speaker's UBM statistics into a total variability space. Introduced by Dehak et al....
- ISO/IEC 17025
- The international standard for testing and calibration laboratories, published jointly by the International Organization for Standardization and the International Electrotechnical Commission. It...
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- NIST SRE (Speaker Recognition Evaluation)
- A competitive benchmarking series run by the National Institute of Standards and Technology since 1996, in which research and commercial teams submit...
Explained in these topics
- Interpreting Biological Evidence in CourtA standardised table published by the European Network of Forensic Science Institutes that maps ranges of LR values to verbal expressions of evidential support...
- Likelihood Ratios and Verbal Scales in Geological EvidenceA recommended scale published by the European Network of Forensic Science Institutes that maps ranges of LR values to standardised verbal phrases such as 'mode...
- Modern Automated Speaker Recognition: NIST SRE and the ENFSI BPMA standardised scale for communicating LR values to courts in plain language, ranging from 'limited support' (LR 1-10) through 'moderate,' 'moderately strong,'...