6.8.4 Analysability measures

What this heading covers

This is an effort property with structural proxies. The best evidence is the time from a defect report to a located cause, or the time from a change request to an agreed impact assessment. The proxies, such as size, nesting or documentation coverage, are useful only if they are validated against that effort. The measure should use a sample of real changes, not a synthetic exercise, and it should name the experience of the people doing the work.

Record position: family 29 of 40 in clause 6, under 6.8 Maintainability, which carries 5 families. It is one of the 40 families a programme has to map its measures to, and its elements are listed below. The heading is 6.8.4 in the public contents; the text behind it is not public.

How a measure for this family is built

Take the median time to locate the cause across a sample of defects, or the median effort to complete an impact assessment across a sample of changes. Report the spread and the sample size. If a structural proxy is used, correlate it with the effort sample and record the result, including a weak one.

What to put in place before publication

1. Use real defects and changes from the last period, not a constructed exercise.
2. Validate any structural proxy against the effort sample.

Evidence to keep

Two questions to ask

• Is this an observed effort or an unvalidated structural proxy?
• What sample of real defects or changes was used?

Where teams usually fall short

• A documentation coverage percentage presented as analysability.

What the number cannot tell you

It cannot tell you why the diagnosis was slow. The number locates the problem area; the observation explains it.

What happens next

Modifiability is the step after analysis: the effort to make the change once it is understood.