Customer Satisfaction Index (CSI)

Hi All,
Is anyone aware of Customer Satisfaction Index (CSI)?
What possible formula can it have?
It is not vendor standard formula, but customized one by the customer (such as NQI I worked previously for an operstor in Turkey).
I am building solution for C Level people, Including CSI for VOLTE, 5G.
I need to define/create some formulas (such as CSI=accessibilty (cssr) *retainability (volte erab drop%) for example.
Any ideas?
Any previous/current experiences from your projects?

NQI is same as you mention (1-drop)*accessibility.
For LTE, NR mos, audio gap can be a included as part of combined formula.

NQI can be, audio gap is a formula by itself as for Ericsson for example, MOS needs tools (swiss qual…) for calculation and we are not using them.
I prefer created formulas or something like that.

If I would be a C level I would require CSI based on MDT processing and not based only on OSS counters.
Only MDT reflects coverage holes and problematic areas in deep indoor.

I agree with you.
MDT is Nokia specific tool.
My Solution based on AI and ML and network predictions (SAS AI/ML) should be according to existing data/KPIs/networks status (bottlenecks/events/loads…).

U can include call setup time and silent calls