SACM2 — Uncertainty characteristic for claims

From the viewpoint of compatibility with ISO/IEC 15026, the most important issue is that SACM contain an "Uncertainty" characteristic or attribute, a key aspect of 15026-2, in order to facilitate use of SACM with ISO/IEC 15026 conformant assurance cases. These would be useful throughout SACM as attributes of assertions or claims (not relations).

Current usage means a need exists for several data type options ­ not necessarily mutually exclusive.

Data Types
• Probability true: 0-1.00
• Type I error: 0-1.00
• Type 2 error: 0-1.00
• Enumeration: None, low, medium, large, unknown
• Standard deviation: real number
One might also want to include a data type with customizable meaning (values: 1-100) that would parallel the data type for “Strength” in present draft if this is retained.

This attribute element is associated with claims (assertions) and not with relations. Current SAEM draft defines characteristics ­ such as “Strength,” and “Confidence” ­ of evidence relations between an EvidenceItem (e.g. exhibit) and a DominAssertion. These relate to uncertainty but are associated with a relation and not with a DomainAssertion (claim). Note that the draft of SAEM states these are one-to-one relations unlike the many-to-one inferential relations in ARM.

Addressed by harmonization to create SACM 2.0.

In redefining SACM 2 it was recognized that there was no established approach (accepted by even a small group of industry) as to how to represent confidence and uncertainty on SACM artefact and argumentation elements. Consequently, SACM 2 deliberately pulled back from standardising in these areas. Confidence information could be added to any model element (if required) using TaggedValue (which could use a community consensus vocabulary established using the Terminology package). In addition, SACM 2 recognises that substantiative assertions about artefacts / evidence should be documented as Claims. It also recognizes the potential (which may be particularly relevant when discussing confidence) to attach metaclaims to any Assertion (see metaClaim association on Assertion).