Scoring
Coverage ratio
The resilience unit of measure: what proportion of applicable resources are configured for a given signal, with signals of zero population excluded.
What it is
For one signal, the proportion of in-scope resources configured as the signal requires. Databases with automated backups over all databases, and so on.
Why a ratio
A count says how many resources are configured well. A ratio says what proportion are, which is the governance question, and it does not move simply because the estate grew.
Zero-population signals are excluded
A signal with no in-scope resources is recorded and excluded from scoring. An account with no databases is not penalised for having no database backups.
Counted per family
Resources are counted once per resource family, so a service exposing two signals from one population does not satisfy a breadth test twice.
The domain score
The mean coverage across signals that survived, provided both governance concerns were evidenced.
What it does not mean
A high coverage ratio across observed signals is not resilience across the estate. The collector does not observe a substantial part of the resilience surface.