I have dummy data for a music streaming service, the data is as follows:-
Monthly uniques = the number of unique listeners on each platform for the entirety of a given month
All-time uniques = the total number of unique listeners that have ever used that platform at the end of a given month (i.e. from platform launch until the last day of that month)
Hours = the aggregate number of listener hours across all listeners
Daily uniques = the number of unique listeners on each platform per day
What is the best method to devise a single metric to measure how successful we were at retaining listeners using the service on a daily basis during December 2014, only using the data above?