Intelligence source and information reliability rating systems are used in intelligence analysis.
A system commonly employed 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.
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:
|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||Cannot be judged||Insufficient information to evaluate reliability. May or may not be reliable.|
|1||Confirmed||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||Cannot be judged||The validity of the information can not be determined.|