Coverage types, Coverage Rate, Management Rate
Coverage types
Unfortunately, a requirement is not always written in a concise and atomic way, and then includes several sub-parts. REQCHECKER™ is able to manage coverage traceability in fine detail for each of the sub-parts by combining several coverages, potentially with the weight of the sub-part that is supported. For each sub-section, the covering text may specify the ‘sub-status’ of the sub-section concerned:
- FRAGMENT This coverage applies to a sub-part of the requirement. The default tag is
#F. - UNCOVERED All or part of the requirement is not covered. The default tag is
#UC. - N/A All or part of the requirement is not applicable and is ignored. The default tag is
#NA.
FRAGMENT, N/A and UNCOVERED tags can be followed by the weight, i.e. percentage of the requirement that is concerned. This percentage can be an integer value, e.g. 20%. It can also be a decimal value with a dot . as decimal separator and with less than 3 digits, e.g. 2.5%. If the percentage value uses more than 3 decimal places, it is considered invalid and is ignored.
In the example below, the requirement is not atomic and is broken down into two parts. Fragmentary coverage is added together to determine whether the parent requirement is fully or partially covered. In this example, 100% weight accumulation is used to set the status of REQ_01 to COVERED.
Important
There are two concepts that should not be confused:
- fragment coverage, where fragment refers to one of the coverages that contribute to establishing the status of the requirement. It is implemented by the coverage tag FRAGMENT.
- partially covered requirement status where partial refers to a requirement that is not fully covered and whose status is PARTIAL.
In the example below, the requirement is not atomic and is broken down into 4 parts. Only 75% is covered and 25% is uncovered. The requirement status is PARTIAL
This page summarises all the tags.
Management rate
management rate = the rate of requirement explicitly managed, excluding requirement with error. It is the number of requirements that are not in error divided by the total number of input requirements.
Coverage rate
coverage rate = number of input requirements that are covered divided by the total number of coverable requirements. A coverable requirement can be covered: is neither not applicable, nor deleted, nor in error.
For example let 10 requirements: - 3 requirements covered, - 1 explicitly not covered, - 2 not applicable, - 4 not yet managed. The management rate is 60% (6/10) and the coverage rate is 75% (¾).
When an requirement is covered by a fragment coverage, the rate is 50% and the status is PARTIAL. When it has at least two fragment coverages, it is considered with the status COVERED.
An advanced features allow to precise the coverage rate explicitly. The coverage rate is more accurate, especially if requirements are not unitary.
Example
For the example below, the coverage rate is 83% and the management rate is 100%:
<<REQ_0040>> #F 13%
…
<<REQ_0040>> #F 30%
…
<<REQ_0040>> #F 40%
…
<<REQ_0040>> #NA 17%
This table shows different combinations of several tags::
| Combination | Meaning | Coverage Status | Coverage Rate | Management Rate |
|---|---|---|---|---|
| #F | The requirement is covered at 50% rate. The remaining 50% are assumed not to be covered. | PARTIAL | 50% | 50% |
| #F + #NA | The requirement is covered at 50%, uncovered at 50%, and N/A at 100%. This is not possible. | AMBIGUOUS_COVERAGE_ERROR | N/A | N/A |
| #F 60% + #F 40% | The requirement is fully covered by two fragment coverages. | COVERED | 100% | 100% |
| #F 60% + #NA 40% | The requirement is covered (60%) except a part of it that is not applicable and can not be covered. | MIXED | 100% | 100% |
| #F 60% + #UC 40% | The requirement is partially covered at 60% rate and 40% is uncovered. | PARTIAL | 60% | 100% |
| #F 60% | The requirement is covered at 60%. Information is missing for the remaining 40%. | INCOMPLETE_MANAGEMENT_ERROR | N/A | 60% |
| #F 60% + #NA 50% | The sum of percentages exceed 100%. This is not possible. | AMBIGUOUS_COVERAGE_ERROR | N/A | N/A |
See Status List Page.