Move metrics from review to dedicated page, and link to quality checks (#125)

* Move metrics from review to dedicated page, and link to quality checks

Author: andyblundell

metrics.md

@@ -0,0 +1,33 @@
+# Engineering metrics
+
+This is part of a broader [quality framework](README.md)
+
+## Purpose & usage
+
+These hard figures help us to measure the effect of improvement work over time, and should be tracked on a monthly basis.
+
+Also, these metrics are intended to be considered as part of [engineering reviews](review.md).
+
+## Essential metrics:
+
+These metrics provide a fundamental level of insight, and so must be tracked:
+
+| Measure | Definition (each calculated over the last 28 days) |
+|:---|:---|
+| Deployment frequency | Number of deployments
+| Quality checks | Presence or absence of frequent, consistent, enforced (with agreed tolerances) of the [engineering quality checks](quality-checks.md) - follow that link for further details
+
+## Recommended metrics:
+
+These metrics provide useful additional insight, and are recommended to be tracked:
+
+| Measure | Definition (each calculated over the last 28 days) |
+|:---|:---|
+| Lead time | Median time between an item being started to when it is done.
+| Change failure rate | Percentage of deployments which result in an incident.
+| Overall incident rate: P1 | Total number of priority 1 incidents which occurred.
+| Mean time to restore service: P1 | Mean time from priority 1 incident starting to when it is resolved.
+| Overall incident rate: P1 | Total number of priority 2 incidents which occurred.
+| Mean time to restore service: P2 | Mean time from priority 2 incident starting to when it is resolved.
+| Overall incident rate: P3 | Total number of priority 3 incidents which occurred.
+| Mean time to restore service: P3 | Mean time from priority 3 incident starting to when it is resolved.

quality-checks.md

@@ -1,6 +1,6 @@
 # Engineering quality-checks
 
-This is part of a broader [quality framework](README.md)
+This is part of a broader [quality framework](README.md) and forms a key part of the [metrics](metrics.md) section.
 
 ## Summary
 

review.md

@@ -27,26 +27,8 @@ This is a **self** assessment review:
 * Scores cannot be compared between teams, but they can help spot common issues which would benefit from coordinated effort between and across teams.
 
 # Metrics
-These hard figures help us to measure the effect of improvement work over time.
-
-## Essential:
-
-| Measure | Definition (each calculated over the last 28 days) |
-|:---|:---|
-| Deployment frequency | Number of deployments
-
-## Recommended:
-
-| Measure | Definition (each calculated over the last 28 days) |
-|:---|:---|
-| Lead time | Median time between an item being started to when it is done.
-| Change failure rate | Percentage of deployments which result in an incident.
-| Overall incident rate: P1 | Total number of priority 1 incidents which occurred.
-| Mean time to restore service: P1 | Mean time from priority 1 incident starting to when it is resolved.
-| Overall incident rate: P1 | Total number of priority 2 incidents which occurred.
-| Mean time to restore service: P2 | Mean time from priority 2 incident starting to when it is resolved.
-| Overall incident rate: P3 | Total number of priority 3 incidents which occurred.
-| Mean time to restore service: P3 | Mean time from priority 3 incident starting to when it is resolved.
+
+These reviews are intentionally subjective and open-ended, unlike [metrics](metrics.md) which are prescriptive and specific. Both of these things should be considered together, so these reviews should take the relevant [metrics](metrics.md) into account.
 
 # Scores and actions