ICD 203 for Intelligence Analysis

"ICD 203" degrees of likelihood for intelligence analysis, in consumable form for reference.

Terms of Likelihood

(a) For expressions of likelihood or probability, an analytic product must use one of the following sets of terms

almost no chance	very unlikely	unlikely	roughly even chance	likely	very likely	almost certain(ly)
remote	highly improbable	improbable (improbably)	roughly even odds	probable (probably)	highly probable	nearly certain
01 - 05 %	05 - 20 %	20 - 45 %	45 - 55 %	55 - 80 %	80 - 95 %	95 - 99 %

Analysts are strongly encouraged not to mix terms from different rows. Products that do mix terms must include a disclaimer clearly noting the terms indicate the same assessment of probability.

(b) To avoid confusion, products that express an analyst's confidence in an assessment or judgment using a "confidence level" (e.g., "high confidence") must not combine a confidence level and a degree of likelihood, which refers to an event or development, in the same sentence.

Code/data reference implementation (JSONic)

icd203_likelihood = {
    "almost-no-chance": [1, 5],
    "very-unlikely": [5, 20],
    "unlikely": [20, 45],
    "roughly-even-chance": [45, 55],
    "likely": [55, 80],
    "very-likely": [80, 95],
    "almost-certain": [95, 99]
}

Credits

• https://fas.org/irp/dni/icd/icd-203.pdf (text version)

• code implementation based on https://github.com/deadbits/mimir/blob/7883a38774e1e3ce1c0acd7287b2a7bb21c20981/mimir/lib/scoring/levels.py

• inspired by SANS CTI 2020 talk "Stop Tilting at Windmills: Three Key Lessons that CTI Teams Should Learn from the Past"

• markdown table generated by https://atom.io/packages/markdown-table-editor