I look after the quality of a vendor which delivers outcome based testing engagements. A part of my role is to review projects from test perspective. These reviews can be
2. On-demand(if a project manager / business stakeholder thinks testing is not doing its job)
3. In case of a high severity incident(HSI)

As a part of on-demand and HSI , depending on the problem statement provided by the business , I would be requesting the test team to provide with me the list of artifacts and other data point,which would be reviewed and a QA report written if the Test team is at fault or not.
I am thinking of writing key indicator library, i.e. list of areas we would often explore to understand if testing is doing its job correctly.Depending on the issue, a subset of the indicators would be utilized to review .

Some areas I have thought of is
1. Communication :- Is this test team communicating its progress or risks/issues. Artifacts to look at would be reports,emails between project and testing
2. Productivity :- to view the productivity of the team . Test execution/Test scripts
3. Defects :- Defect resolution/Defects rejected/Type of defects raised/defect injection ratio
4. Product knowledge :- knowledge level of the test team towards the application. e.g. experience or the documentation
4. Risk/Issue register :- to understand if concerns where raised by the test team for any particular hold up
5. plan vs actual :- Tracking progress to plan.

Suggestions to add to this list of indicators would be appreciated