Updated: Feb 11, 2021
The Admiralty System or NATO System is a method for evaluating collected items of intelligence. It consists of a two-character notation, evaluating the reliability of the source and the assessed level of confidence on the information.
Reliability of Source
A source is assessed for reliability based on a technical assessment of its capability, or in the case of Human Intelligence sources, their history. The notation uses Alpha coding, A-F:
A. Completely reliable: No doubt of authenticity, trustworthiness, orc ompetency; has a history of complete reliability
B. Usually reliable: Minor doubt about authenticity, trustworthiness, or competency; has a history of valid information most of the time
C.Fairly reliable: Doubt of authenticity, trustworthiness, or competency but has provided valid information in the past
D. Not usually reliable: Significant doubt about authenticity, trustworthiness, or competency but has provided valid information in the past
E. Unreliable: Lacking in authenticity, trustworthiness, and competency; history of invalid information
F. Reliability cannot be judged: No basis exists for evaluating the reliability of the source
An item is assessed for credibility based on likelihood and levels of corroboration by other sources. The notation uses a numeric code, 1-6.
1. Confirmed by other sources: Confirmed by other independent sources; logical in itself; Consistent with other information on the subject
2. Probably True: Not confirmed; logical in itself; consistent with other information on the subject
3. Possibly True: Not confirmed; reasonably logical in itself; agrees with some other information on the subject
4. Doubtful: Not confirmed; possible but not logical; no other information on the subject
5. Improbable: Not confirmed; not logical in itself; contradicted by other information on the subject
6. Truth cannot be judged: No basis exists for evaluating the validity of the information
You would use it when providing information gained from a source to provide a sense of the reliability and quality of the information. So for example, you might rate a piece of information as being:
C3 (Fairly reliable source and possibly true) as versus another piece of information which is,
A1 (Completely reliable and verified by other independent sources)
It is somewhat subjective but is a useful tool which provides a couple of extra dimensions presenting information.
Closely related to Admiralty Scale is the Analysis of Competing Hypotheses (ACH). ACH is a robust way to evaluate information in the face of uncertainty.