Likelihood Term

NIKOLAI proposes Likelihood Term as a controlled ladder of ordinal terms (or, where a source permits it, a numeric band) expressing the probability that a harm or claim holds, with a required `likelihood.scheme` reference identifying which source's scale is in use, and an explicit 'unanchored' value for the common case where a source uses ordinal language without ever defining what probability range each term denotes. This is a NIKOLAI editorial proposal; no cited source has adopted NIKOLAI's specific scheme-reference mechanism.

This is CASRAI's own proposed definition, not a definition any named organisation has agreed to. See what NIKOLAI is and is not.

Source of record

Where this definition comes from

Anthropic Risk Report, August 2026, Table 2.4.A discussion
“the brief records the scale as "'very low', 'low', 'moderate/somewhat', 'high'" and notes it is never numerically anchored. CB-2 baseline per-decade probabilities "as high as 1 in 50 or so, or as low as 1 in 20,000".”
https://www-cdn.anthropic.com/f61d49fa5596956a5dec75fea0e973bf6a6a8378/Redacted%20Risk%20Report%20August%202026%20.pdf
EU GPAI Code of Practice, Safety and Security Chapter, Measure 3.4
“Signatories will estimate the probability and severity of harm for the systemic risk. ... Estimates will be expressed as a risk score, risk matrix, probability distribution, or in other adequate formats, and may be quantitative, semi-quantitative, and/or qualitative”
https://ec.europa.eu/newsroom/dae/redirection/document/118119

Crosswalk

How named organisations use this concept

Every row below is a shadow mapping. A shadow row is CASRAI's own reading of a published document. No lab, evaluator or regulator named on a shadow row has declared, endorsed, or been consulted on it. That changes only when an organisation files its own Mapping Declaration.

Organisation	Their term, as published	Match & verification	Source
AnthropicShadow mapping Anthropic Risk Report, August 2026	“Ordinal terms across "probability of occurrence, expected harm conditional on occurrence, fraction unmitigated, and overall risk"; scale "'very low', 'low', 'moderate/somewhat', 'high'", never numerically anchored. CB-2 baseline per-decade probabilities "as high as 1 in 50 or so, or as low as 1 in 20,000".”	closeCL confidence: high	Anthropic Risk Report, August 2026
OpenAIShadow mapping OpenAI Frontier Governance Framework	“Severity and probability are estimated for CBRN, cyber and loss of control (§2.2); "The probability side of 'severity and probability' is not quantified at all" (brief gap).”	noneDU confidence: medium	OpenAI Frontier Governance Framework
Google DeepMindShadow mapping Gemini 3.7 Flash FSF Report	“"reasonable confidence" and "moderate confidence" are used for rule-out determinations "but never defined" (pp.3, 13).”	noneDU confidence: medium	Gemini 3.7 Flash FSF Report
xAIShadow mapping xAI Frontier AI Framework, 30 Jun 2026	“"Systemic risk estimation: estimating 'the probability and severity of harm for the systemic risk using state-of-the-art risk estimation methods'" (s.2.2(4)). No scale given.” This row cites xAI's Frontier AI Framework (30 Jun 2026, {FAIF26}), whose PDF metadata /Title reads "Privileged/Confidential DRAFT working FRAMEWORK DOC" with no xAI statement found disambiguating draft vs. final status (ALIGNMENT-MATRIX.md §6 item 4, unresolved as of the source pass). Treat as citing a document of unconfirmed final/draft status.	noneDU confidence: medium	xAI Frontier AI Framework, 30 Jun 2026
EUShadow mapping EU GPAI Code of Practice, Safety and Security Chapter	“Measure 3.4 "Systemic risk estimation": estimates "will be expressed as a risk score, risk matrix, probability distribution, or in other adequate formats, and may be quantitative, semi-quantitative, and/or qualitative", e.g. "a qualitative systemic risk score (e.g. 'moderate' or 'critical')", "a qualitative systemic risk matrix (e.g. 'probability: unlikely' x 'impact: high')", or "a quantitative systemic risk matrix (e.g. 'X-Y%' x 'X-Y EUR damage')" -- the only source in this corpus that explicitly permits and names a quantitative probability-times-damage format alongside qualitative bands.”	closeCL confidence: high	EU GPAI Code of Practice, Safety and Security Chapter
International AI Safety Report 2026 (Chair: Yoshua Bengio)Shadow mapping International AI Safety Report 2026	“Describes risks qualitatively -- "already materialising, with documented harms" versus "more uncertain but could be severe if they materialise" -- and frames the problem as an "evidence dilemma"; states "Our global risk management frameworks are still immature, with limited quantitative benchmarks and significant evidence gaps." No numbered likelihood/severity matrix is adopted on the evidence read.” IMPORTANT provenance caveat carried from ALIGNMENT-MATRIX.md: the "immature ... limited quantitative benchmarks" sentence was confirmed (16 Sep 2026 pass) to be a quote from Minister Ashwini Vaishnaw's framing statement in the report's own PR Newswire launch release, NOT the report's analytical body text -- it must not be cited as "the report says" without that distinction. Separately, the ~300-page PDF body (arXiv:2602.21012) could not be parsed in the source pass, so a structured likelihood/severity table in an unread chapter cannot be ruled out; this remains an open [VERIFY] gap, not a settled absence.	noneDU confidence: medium	International AI Safety Report 2026

What do these codes mean?

exact: The source term is equivalent to this element
close: The source term is close but not equivalent to this element
broad: The source term is broader than this element
narrow: The source term is narrower than this element
none: No mapping claim — used for false-friend and declared-but-undefined rows
EQ: Equivalent
CL: Close
BR: Source is broader than the element
NR: Source is narrower than the element
FF: False friend — same or similar label, different meaning
DU: Declared but undefined by the source
UV: Unverified

Related, not mapped

Pointers that are not crosswalk claims

These sources mention this concept but do not define or map it clearly enough to count as a crosswalk row — noted here so the research is visible without overstating it as a mapping.

California SB 53
RL -- an undefined qualitative standard in statute, a pointer rather than a controlled term mapping.
California SB 53
Frontier Model Forum
RL -- framing commentary on the state of the field's likelihood quantification, not itself a likelihood-term scale.
Frontier Model Forum: Risk Taxonomy and Thresholds
CISA (U.S. Cybersecurity and Infrastructure Security Agency)
RL -- cited in the source brief via an internal research file, not a public URL in the supplied sources table; recorded as a pointer only, no URL invented.

Gap

No source anchors its likelihood words. NIKOLAI should require a `likelihood.scheme` reference and allow "unanchored" as an explicit value. This is no longer only an absence in the corpus NIKOLAI happened to read -- the International AI Safety Report 2026 independently confirms it is an absence in the field itself (subject to the minister-attribution caveat above), which strengthens rather than weakens the case for NIKOLAI's proposed `likelihood.scheme` field.