Intelligence source and information reliability

Intelligence source and information reliability rating systems are used in intelligence analysis. This rating is used for information collected by a human intelligence collector.^[1][2] This type of information collection and job duty exists within many government agencies around the world.^[3][4]

According to Ewen Montagu, John Godfrey devised this system when he was director of the Naval Intelligence Division (N.I.D.) around the time of World War II.^[5]

The system employed by the United States Armed Forces rates the reliability of the source as well as the information. The source reliability is rated between A (history of complete reliability) to E (history of invalid information), with F for source without sufficient history to establish reliability level. The information content is rated between 1 (confirmed) to 5 (improbable), with 6 for information whose reliability can not be evaluated.^[6]

For example, a confirmed information from a reliable source has rating A1, an unknown-validity information from a new source without reputation is rated F6, an inconsistent illogical information from a known liar is E5, a confirmed information from a moderately doubtful source is C1.

The evaluation matrix as described in the Field Manual FM 2-22.3 (see also Admiralty code):^[6]

Source reliability

	Rating	Description
A	Reliable	No doubt about the source's authenticity, trustworthiness, or competency. History of complete reliability.
B	Usually reliable	Minor doubts. History of mostly valid information.
C	Fairly reliable	Doubts. Provided valid information in the past.
D	Not usually reliable	Significant doubts. Provided valid information in the past.
E	Unreliable	Lacks authenticity, trustworthiness, and competency. History of invalid information.
F	Reliability unknown	Insufficient information to evaluate reliability. May or may not be reliable.

Information credibility

	Rating	Description
1	Confirmed by independent Sources	Logical, consistent with other relevant information, confirmed by independent sources.
2	Probably true	Logical, consistent with other relevant information, not confirmed.
3	Possibly true	Reasonably logical, agrees with some relevant information, not confirmed.
4	Doubtfully True	Not logical but possible, no other information on the subject, not confirmed.
5	Improbable	Not logical, contradicted by other relevant information.
6	Difficult to say	The validity of the information can not be determined.