Implement "Membership cancellations" report

[parafoxia]

trafficstars

Summary

Description:

This report provides statistics showing why users canceled their channel memberships.

The report implements one new dimension:

• membershipsCancellationSurveyReason (0 or 1)

It also implements one new metric:

• membershipsCancellationSurveyResponses (required)

Why?

Feature completeness.

Ideal implementation

No response

Additional information

No response

Contribution

• [x] I wish to contribute this feature.

Checklist

• [x] I have searched the issue tracker for duplicate issues and couldn't find any. If this is a follow-up issue, I have specified as such.